TOTW — Growing Corn
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gary
Posted: Mar-13-2005 at 7:34am
Growing Corn in the Maritime PNW
No, I am not going to tell you to plant your corn now despite the fact that the first half of March has been as warm as a ‘normal’ first week of May. That is assuming you are a home gardener. If you grow corn for a farmers’ market, get prepared and ready for a string of warm days like we had in early and mid-April last year. The market rewards of having fresh corn in late July with competitors 3-4 weeks behind you will put lines in front of your booth that must be seen to be believed.
Let’s put some planting dates in perspective using a popular sweet corn hybrid, Bodacious. In 2004, with 75% of the weeks from April 1st to mid-August warmer than normal, corn planted April 3rd came to market on August 1st, May 5th corn was harvested about August 20th, and May 30th corn by Sept 5th. Notice those almost 60 days between sowings ended with about 30 days separation at harvest. And if some of your first sowing was protected early by plastic, you harvested it 10+ days ahead of the non-plastic corn.
These are the results of a good friend of mine who has grown corn for the Olympia Farmers’ Market for many years. For ten of those years, I have used my weather data to forecast his harvest dates and help him schedule his sowing dates so they come to harvest in succeeding weeks for the Market.
I first learned of planning vegetable sowings this way in a pair of British books titled Know and Grow Vegetable (1 & 2), 1979-81. “The basis of the method is that , as plant growth rates are related to temperature, the intervals between successive sowings should b e varied depending on the actual temperatures since the last sowing, rather than intervals based on average seasonal trends.” . .
“At present this method is successfully used for programming commercial production of peas, beans, sweet corn, and tomatoes, and experimentally for predicting the harvest times of lettuce, carrot and mini-cauliflower.”
Remember this was written 25+ years ago. I have not researched what vegetables are grown this way in 2005. Reading it sure did peak my interest to help my friend Dick Rutledge with his corn sowing. The technique is very similar to the “heating degree days” methods my industry used to schedule heating fuel deliveries for much of the last century.
Let me quote Purdue University:
“Growth and development of corn are strongly dependent on temperature. Corn develops faster when temperatures are warmer and more slowly when temperatures are cooler. For example, a string of warmer than normal days in late spring will encourage faster leaf development than normal. Another example is that a cooler than normal grain filling period will delay the calendar date of grain maturity.
“The phrases “string of warmer than normal days” and “cooler than normal grain filling period” can be converted mathematically into measures of thermal time by calculating the daily accumulations of heat. Commonly used terms for thermal time are Growing Degree Days (GDDs), Growing Degree Units (GDUs), or heat units (HUs).
“Different methods exist for calculating heat units depending on a) the crop or biological organism of interest and b) the whim or personal preference of the researcher. The calculation method most commonly used throughout the U.S. for determining heat unit accumulation relative to corn phenology is the formula first suggested by the National Oceanic and Atmospheric Administration in 1969 and labeled as the ‘Modified Growing Degree Day’ formula in 1971.
“This method calculates daily accumulation of GDDs as the average daily temperature (degrees F) minus 50. The “modification” refers to the limits imposed on the daily maximum and minimum temperatures allowed in the calculation. Daily maximums greater than 86 degrees F are set equal to 86 in the calculation of the daily average temperature. Similarly, daily minimums less than 50 degrees F are set equal to 50 in the calculation.
“Example 1: If the daily maximum temperature was 80 degrees F and the minimum was 55 degrees F, the GDD accumulation for the day would be ((80 + 55)/2) – 50 or 17.5 GDDs.
“Example 2 (Illustrating the limit on daily maximums): If the daily maximum temperature was 90 degrees F and the minimum was 72 degrees F, the GDD accumulation for the day would be ((86 + 72)/2) – 50 or 29 GDDs.
“Example 3 (Illustrating the limit on daily minimums): If the daily maximum temperature was 68 degrees F and the minimum was 41 degrees F, the GDD accumulation for the day would be ((68 + 50)/2) – 50 or 9 GDDs."
On May, normal daily GDD accumulations for Olympia are about 7 GDDs. By late July, the normal daily accumulation peaks about 15 GDDs. For a typical corn growing season in Olympia, say from late April to late September, the total seasonal accumulation of GDDs is about 1,800 GDDs.
You can find historical normal GDD accumulations on a monthly basis for your location by visiting your state site of the Western Climate Summaries. You can choose from 200+ Washington sites at:
WASHINGTON CLIMATE SUMMARIES
Click at the top left to see other states. When you get to your location, scroll down to click on the link to “Growing Degree Days”. The corn units are listed at the bottom by month and accumulated sum. Other temperature bases are there also. Should we experiment with the 40F base for lettuce or peas?
I have reached the 1,000 word point now and I need to get hardware store items to allow a daughter and son-in-law install a new “low flow” for my boss. (More water for the grass?)
Under things to come later:
Gary
Olympia, Sunset Zone 5, USDA Zone 8
DebbieTT
Location: Washington, Kitsap Peninsula
Posted: Mar-13-2005 at 10:14pm
Once the soil has warmed this much will it cool off significantly and make that much difference? Amazing getting 10 days difference with corn using plastic protection. Is this cloches?
gary
Location: Washington, Puget Sound Corridor
Posted: Mar-14-2005 at 8:48am
Day 2
For comparison purposes, here are some GDD’s in our region during a May 1st to Sept. 30th season.
* - April 1st to Sept 30th Season
I used April 1st as the start at the two coastal locations and the AgriMet soil temp data from Brookings shows that you can get 60F germinating temps in April. Even though the GDD’s on the coast look like poor candidates their warm Septembers should reward you with good corn if you use an early variety. My experience with Dick’s Bodacious shows that it is ready for harvest at about 1,250 GDD’s.
How does this scheduling work? Let’s take a look at a crop of Golden Jubilee sown near the Olympia AP on May 15th in a ‘normal’ weather year. Below is a list of events from sowing to harvest of this variety in the PNW.
==EVENTS TABLE===
1. 104 DDs after planting: First emergence from soil – May 27th
2. 308 DDs after planting: 5 leaf stage – June 17th
3. 445 DDs after planting: 7 leaf stage – June 30th
4. 883 DDs after planting: 5 inch tassels – August 1st
5. 960 DDs after planting: 10 inch tassels – August 7th
6. 1005 DDs after planting: 5% silk emergence – August 10th
7. 1062 DDs after planting: 50% silk emergence – August 14th
8. 1145 DDs after planting: 95% silk emergence – August 20th
9. 1288 DDs after planting: 50% brown silks develop – August 31st
10. 1412 DDs after planting: 95% brown silks develop – September 11th
11. 1539 DDs after planting: Fresh market harvest – September 22nd
12. 1597 DDs after planting: Processing market harvest – September 28th
Bodacious would be ready for Market about August 28th using the same sowing and weather. Notice also that there are 122 DD’s in the nine days between August 1st and 10th or 14 per day. 6 weeks later there are only 127 DD’s between Sept. 11th and 22nd or 11per day. To space your harvests weekly you need to space your sowing by the GDD’s of the harvest time intervals. In other words, we need to sow Bodacious 143 DD’s (1288-1145) before May 15th to harvest it on August 20th. A sowing 124 DD’s (1412-1288) after May 15th would be ready to harvest on September 11th.
Obviously, the ability to calculate daily heat unit accumulations is dependent on your having access to daily maximum and minimum temperatures. If you do not have your own max/min recording thermometer, you can guesstimate the daily highs and lows by manually recording the temperatures shortly after sunrise (approximate daily low) and late in the afternoon (approximate daily high).
But notice the GG’s at emergence point? The emergence of your last sowing is a good indicator of the time to sow again. This what good market gardeners are doing. It is easier to consistently sequence one variety than try to get 6-10 bins a day each week working with different variety harvest cycles. An early variety can give you several crop cycles in our growing season. Last year Bodacious sown on May 14th, May 30th, June 9th, and June 16th, was ready to eat on August 25th, September 2nd, 11th, and 19th.
Under things to come later:
Gary
Olympia, Sunset Zone 5, USDA Zone 8
gary
Location: Washington, Puget Sound Corridor
Posted: Mar-14-2005 at 9:11am
Debbie’s questions:
Once the soil has warmed this much will it cool off significantly and make that much difference?
I read my soil temps about an hour after sunrise each day. I find that without rainy conditions, it seems to be a couple of degrees above the average temperature. My timing would seem to give me the minimum temp for that day. The fastest way to cool the soil from today’s 52F (with frost in the neighborhood this AM) reading would be to get rain on a 40F day Wednesday. The cold or warm moisture changes the temps the fastest. The later we get in the year make that 40F rain less and less likely. The cooler nights this week have only dropped my temps 3-5 degrees from last week.
Amazing getting 10 days difference with corn using plastic protection. Is this cloches?
I guess I’ll call what Dick uses a modified flat cloche. As he does his seed drilling to sow his seeds, attachments on the back of dig two small trenches, sow the seeds in the low areas, lays down a 5 foot wide roll of clear plastic which has ventilation slits, and then rolls dirt over the outside edges to hold it in place. We could accomplish something similar with clear plastic or GroTherm in our home gardens.
Gary
Olympia, Sunset Zone 5, USDA Zone 8
DebbieTT
Location: Washington, Kitsap Peninsula
Posted: Mar-15-2005 at 6:59pm
Thanks Gary, this information is awesome. The soil temp information help in other situations too.
Where are all the other vegetable growers? It may be too early, they haven't thawed out yet.
Will you be recommending good varieties? Oops just read that is coming up! Can't wait to see whatever else you forgot, too.
When the going gets tough, the tough need a hug.
gary
Location: Washington, Puget Sound Corridor
Posted: Mar-20-2005 at 7:48am
Been tied up with other things (NCAA pools, Dawgs, etc.) but let’s talk a little on varieties. First though I should pass you a link to our resident advisor, Trav. You can see his article on corn at:
Sweet, Sweet Corn
Colorado State provides another simple explanation of the different hybrid types:
On a corn seed packet, you may find a short genetic abbreviation which describes the type of sweet corn; different types require different cultural conditions:
1) "Normal" sweet corn (su) - Kernels contain moderate but varying levels of sugar, depending on variety. Sugars convert to starches rapidly after harvest.
2) "Sugar-enhanced" (se, se+, or EH) - Genes in this type modify the su gene, resulting in increased tenderness and sweetness. Additionally, conversion of sugar to starch is slowed.
3) "Super-sweet" or "Xtra-sweet" (sh2) - This gene, (sh short for shrunken), creates greatly increased sweetness and slow conversion of starch. The dry kernels (seeds) of this type are smaller and shriveled.
A few years ago, I saw an even better way of explaining the differences in these sugar added hybrids. The author described su as the corn you wanted to pick and husk after the water was boiling. The se’s could be harvested in the next county, and the sh2’s should come from the next state.
I agree with Trav on the supersweets when he says, “These high sugar types do have a couple drawbacks. They are not as vigorous as SU corn, and so require warmer soil temps for germination - a MAJOR drawback here in the Maritime Northwest. Also supersweets must be isolated from other types of corn; if they cross-pollinate their ears will revert to field corn quality (in a word, yucky). In my personal opinion the supersweets are much too sweet.”
Our local seed sellers like Territorial and Westcoast don’t have many varieties of them in their catalogs. Gurneys, on the other hand lists 8 sh2’s/triplesweets or half of their total of 16 sweet corn varieties.
Gurney’s also says that Bodacious will put 18 rows on 8 inch ears. 14-16 I have seen but never 18. This is another measure of Midwest heat units compared to ours. Later Bodacious sowings produce more rows on each larger ear because they grow those leaves larger and faster. Beware of what the catalog says. You must always consider where your seed company is mainly selling their products.
Ed Hume and others still have Early Sunglow that I used to grow but compared to Bodacious’ much larger, sweeter ears, I would not grow it. Trav’s Golden Jubilee is a great main season, as he calls it variety. The se’s do hold in the field longer than su’s like Jubilee especially if you are not a young corn eater like I am (I do wait until the silk points are gone from the kernels,barely.).
We’ll get into the space required later but just consider two Market crops to decide if you want to grow your own corn. A row of ‘boutique’ potatoes like Red Gold, the fingerlings, and the others you can buy at Farmers’ Market will produce about 2 lbs. of potatoes per foot which can cost you $4 to buy at the early potato harvest. You’ll get 2 to 3 ears (max) per foot of corn row which you can buy at 3-4 ears for a dollar at the Market. As long as I can depend upon Dick and now his sons to produce a great ear, I will not try to grow my own especially as they sell at the farm all week. (And I’ve been known to pick my own too.)
Were I going to grow corn again, I would sequence four sowings of one variety like Bodacious rather than try to match harvests by varieties. Planting four rows of corn in four-foot long sequenced sowings will give you about 30 ears of corn in each of the four harvests.
Trav and all the seed catalogs warn you of another drawback to the super sweets. They must be isolated from other corn. My market grower friend has tried some of these in the last few years but hasn’t thought enough of them to put them on sale. He also has given up on the white and bi-color hybrids he has tried. We feel that it is a function of the ‘density’ in summer heat units that we do not have compared to other locations. Those who grow in the Willamette and further south maybe able to use these varieties. I would tour some of the farm stands in the valley like those just NW of Eugene and do your own taste tests. Purchases in early August, late August, and mid-September will give you a good idea of which varieties you may want to grow.
And remember to consider what the growing season was like when you are comparing varieties. The best of all worlds would be for your main season corn to ripen in the high sun and heat of July and August but that doesn’t happen often so taste comparisons can be tricky.
Sorry about the delay since the last post. I hope to be able to finish up in the next few days.
Gary
Olympia, Sunset Zone 5, USDA Zone 8
gary
Location: Washington, Puget Sound Corridor
Posted: Mar-21-2005 at 12:43pm
Spacing: The most common advice seems to be that corn should be sown to a final spacing of 30-36” between rows and 8-12” between plants in the row. The larger spacing would be for a ‘main season’ variety while a ‘early’ type could be spaced closer together. I do know that corn shows its grass family affection for sunshine so try to give it one of your best sun locations. (Maybe a 3-year rotation of corn, melons, and tomatoes or add a fourth year of peas/bush beans to add nitrogen?)
Lee Reich recommends 6-8 seed hills sown in hills staggered at 18” down a 30” wide raised bed. He thins to 3-4 plants per hill. He claims “yields are an ear or two per square foot of bed, whick is not bad if you consider that the planting bed could also (be) used for other vegetables, earlier and later in the season.”
The first host of Victory Garden, Jim Crocket, used to plant seeds on 12” centers in a four foot wide raised bed. I found that this did take care of the wind pollination but only gave me one ear per plant (my sun starved garden?).
My mother used to advise me to sow three seeds for each plant you want to have; one to rot, one for the crows, and one to grow. Trav gives good advice on waiting for 60F soil temps at 9AM before sowing. If you then cover the soil with clear plastic to keep cold rains off and help keep the soil warm during germination, you should be able to get most of your seeds to grow. Remove the plastic once the plants emerge as you can do more damage from heat burn than light frosts. You can also use treated seed to reduce your germination losses.
Once your crows learn about those kernels down there under that shoot, they can walk right down a row pulling every plant. I have not had that problem in my garden but we did in my mother’s. I stopped most of that by placing chicken wire on the bed for a few years. They seemed to stop walking on the bed and after 3-4 years, they did not bother a bed without the wire (parents did not teach the offspring to eat this food?). Crows are quite trainable like that. When I walk my friend’s field it is obvious that he has trained them how far shotgun pellets travel as they maintain that distance from you at all times. You can get them to jump to the air if you clap your hands (shades of my youth when we could get $0.25 for a pair of crow’s feet.)
Fertilizer: The common fert recommendations seem to settle 3# per 100 row feet (or bed sq ft) prior to sowing (5-10-10, complete organic fert, cottonseed or soybean meal). Most also recommend at least a second feeding near the knee high stage (that used to be my last weeding). Now you might want to mulch the bed with a layer of compost to control the weeds, say an inch. But I think that you should still fert, say with a liquid, through the mulch. Do not mix in the compost mulch after sowing as you will tie up some nitrogen and you’ll lose the weed prevention aspect of the mulch. In a large field of corn, like Dick’s, weed control is very important. You can get weeds taller than the corn if you don’t control them.
Gary
Olympia, Sunset Zone 5, USDA Zone 8
DebbieTT
Location: Washington, Kitsap Peninsula
Posted: Mar-22-2005 at 5:44pm
Originally posted by gary
Crows are quite trainable like that. When I walk my friend’s field it is obvious that he has trained them how far shotgun pellets travel as they maintain that distance from you at all times. You can get them to jump to the air if you clap your hands (shades of my youth when we could get $0.25 for a pair of crow’s feet.)
How times have changed since those days! You would get in a heap of trouble now. Crows are very smart and if they weren't such pests to some they probably would be better liked. I think they are fun to observe.
But I wanted to add that floating row covers will keep the crows out too.
I know raccooons can be serious problems in my corn garden. Although I haven't grown corn for quite awhile. Those buggers would lay a bed flat in one night. I always did the intense beds and like you only one corn per stalk. Would thinning it more, help?
This year I am growing some ornamental corn so I am paying attention here.
Lisa A
Location: Oregon, Greater Portland Metro
Posted: Mar-22-2005 at 6:50pm
gary, you mentioned that one drawback to the supersweet varieties is that they need to be isolated from other corn. since corn is wind-pollinated [i am remembering correctly, aren't i?) just how isolated does a corn patch need to be? if my neighbor on a typical suburban lot grows one type, am i in trouble if i grow a supersweet variety?
btw, thanks for all this great information.
Gardening requires lots of water - most of it in the form of perspiration. - Lou Erickson.
JeanneK
Location: Oregon, Greater Portland Metro
Posted: Mar-22-2005 at 7:45pm
6-8 seed hills, hmm? I wondered how many I should grow to get any kind of yield. When I tried to grow corn in the past, I wasn't able to get them to ripen. Probably has a lot to do with the GDD's. Thanks for the comparisons. I find it fascinating to compare temperatures in different geographic regions. I am interested in the wind pollinating aspect also. Good question, Lisa. Thanks for the specs on how many rows of corn to plant.
Jeanne gary
Location: Washington, Puget Sound Corridor
Posted: Mar-24-2005 at 8:21am
Isolation
Gurney’s: If planting more than one cultivar, space the corn stands at least 250' apart to prevent cross-pollination. An alternate method to prevent cross-pollination of different corn cultivars is to stagger planting dates of the different cultivars by a minimum of 14 days.
Johnny’s: Plan to separate home garden plantings of Super Sweets by distance of 25 feet (acreage plantings, 100 feet) from non-Super Sweet varieties, or by time, a 10-day planting date/maturity difference. Extensive crossing with non-Super Sweet will result in tough, starchy kernels in both types.
Territorial: To grow great Supersweet corn, you must isolate it by time or distance from and other corn.
West Coast Seeds: These corns must be isolated from other varieties by 8m (25 ft.). Or you can plant other corn that will mature 10-12 days before or after the sh2 variety.
North Willamette Research comments for commercial corn production:
ISOLATION
Isolation is necessary from two points of view, color and kernel quality (sugars and texture). Since colored kernels in white varieties are very obvious, a 500 foot or more isolation distance is recommended between white and colored varieties. A two week difference in silking may also be used, but is less reliable. For isolation regarding kernel quality considerations the following is recommended:
Supersweet corn varieties and other new types of corn requiring isolation from standard sweet types should be isolated based on their Isolation Class categorization. The use of 2-4 border rows helps minimize contamination in all situations described below. Isolation may be accomplished in three ways, by distance, time of pollination, and blocking. Isolation by distance is the preferred method.
Isolation by distance
Observations at Oregon State University over several seasons indicate that if no isolation is used between standard sweet (Isolation Class II) and supersweet types (Isolation Class III), outcrossing of kernels in adjacent rows and extending for 6 to 10 rows (15 to 30 feet -- Ed.) into each type, is high enough to render the ears from these rows unsalable. This outcrossing can result in over 50% of the kernels on ears in adjacent rows being starchy. Outcrossing drops off rapidly beyond 10 rows, until at about 100 feet, only up to 1% of kernels (up to 4 kernels per ear) may be starchy. This level of outcrossing is probably not discernible by fresh market buyers or consumers.
Where large plantings are made for fresh market production, a distance of 250 feet is recommended between Isolation Classes I, II, and III. Where isolation of fields is convenient, maximum isolation would not need to exceed 600 feet, which is a conservative assumption based on distances used for seed production, where isolation is even more important. Whenever practical:
1. Locate supersweet varieties (Isolation Class III) upwind of varieties in all other isolation classes since outcrossed kernels may be more apparent in the supersweet ears.
2. Mechanically top standard sweet corn plantings, of the variety Jubilee, two leaves above the top ear after the silks have turned brown, and before nearby supersweet plantings begin to silk. Topping an earlier nearby supersweet planting, or a standard sweet variety other than Jubilee would also be helpful, but timing and the effect of topping on yields of supersweet corn, and other standard sweet varieties, have not been researched adequately. Unacceptable reductions in yield have been observed in limited research on topping of other varieties.
3. In small sequential fresh market plantings, plant all varieties of one Isolation Class (I, II, OR III) together in a block located 250 feet or more from a block containing sequential plantings of varieties of any other Isolation Class. For best quality results, varieties of different subclasses (IIa, IIb, OR IIc) should be isolated 50 feet from other subclasses within the same Isolation Class.
Isolation by time of pollination
If the 2-3 week pollination time difference is to be used as a means of isolation between Isolation Classes, and plantings of different Isolation Classes are adjacent, several things need to be considered:
1. The later planting must not be planted based on calendar day difference, but rather on growth stage or heat units. Specifics on this need to be obtained from the individual seed company regarding their variety. The maturity difference between the two types of corn has to also be figured into the planting date difference. Assuming the standard sweet (Isolation Class II) and supersweet (Isolation Class III) varieties have the same maturity (days from seeding to pollination), delay planting the other Isolation Class of corn until the first planting has 8 or more leaves, or 300 or more heat units (base 50 F) have elapsed. (Emphasis mine)
2. To obtain an effective two to three week spread at pollination, the early planting must germinate uniformly or else late germinating plants may cause problems.
3. Whenever possible, mechanically top the early planting just before the later one begins to silk. Fresh market growers may choose to hand-top the late flowering plants or suckers in 10 or 20 rows adjacent to the later planting. Be especially careful of late flowering suckers in these rows.
Isolation by blocking
Fresh market growers who have a use for, or a market for ensilage, may also choose to "block" plantings that have not been isolated by distance or pollination time. This practice consists of walking progressively further from the boundary of the two plantings, examining a sample of ears in each row visually until one finds the row where the outcrossing incidence is acceptable, abandoning the intervening rows (or using them for silage). In Florida, experience has shown that 6-10 rows (sometimes up to 20 rows) may need to be skipped.
Most of us do not have the space to accomplish most of the distances above so we have to buy out the neighbors (their corn sowing, at least). If I didn’t say it before, Dick has not had much luck with white corn. Again, I think it is the consistent heat units required. It works some years but not others. It was also a marketing problem for him as the timing and isolation didn’t allow him to have it consistently available.
I was saving the raccoons for later. I intend to bring them up under a section titled, How Do You Know When to Harvest? The answer is, “Start your harvest three days after the raccoons do.”
Yes, thinning the stand will help increase the yield, especially if you are short of sun.
Gary
Olympia, Sunset Zone 5, USDA Zone 8
Lisa A
Location: Oregon, Greater Portland Metro
Posted: Mar-24-2005 at 10:57am
thanks, gary. great, well-reseached info as always.
Gardening requires lots of water - most of it in the form of perspiration. - Lou Erickson.
gary
Location: Washington, Puget Sound Corridor
Posted: Mar-26-2005 at 3:18am
A few years ago The Victory Garden visited a market corn grower in Concord. They discussed pests and harvesting as follows:
Pests
To begin with, there are weeds, although they're hardly a surprise. As a farmer, Steve can hardly handpick each and every unwanted root, so he uses a combination of mild herbicide and mechanical methods to combat his weeds. But what of other, peskier pests?
The corn earworm is certainly the bane of many a corn grower. At night these pests (in moth form) alight in the corn silks where they lay their eggs, and the larvae soon hatch to feed on the kernels at the top of the ear. Luckily for the small-scale home gardener Steve has a good organic method you can use to control the earworm: mineral oil. All you need is a spray bottle. Right around the time your corn is reaching maturity — when the silk begins to turn brown — spray the ears of corn with a dose of mineral oil. That will coat any eggs that may be infesting the silk, preventing them from hatching successfully and getting to your corn before you do.
Around the same time you may also discover your corn is being visited by a couple of other intrepid intruders, namely, raccoons and birds.
"They like it about a day or two before you do," Steve says, referring to the corn-eating habits of raccoons, frequent pests to corn growers. The masked bandits love to come in at night and strip down the corn, sometimes ripping the ears all the way off the stalks. He cautions that they're wily too, so outsmarting raccoons can be a challenge. Traps are available though to help catch the rascals humanely if they've found your crop. (Looking on the bright side, Steve does note that the evidence of raccoon dining is at least a good indication that harvest time is only a couple of days away.)
Blackbirds and crows can pose yet another — and since they tend to descend in groups, potentially more costly — threat to a crop of corn. Their general practice is to shred the ears from the top down, often only eating a few kernels, but nonetheless leaving the ear publicly unsaleable, if not privately inedible. That in mind, it's easy to imagine how as few as a dozen or so birds, spoiling an ear or two each, can wreak fast havoc on your backyard stand of corn. To fend off this nuisance at Verrill Farms, Steve uses a propane-powered noise cannon. For more domestic purposes, there are a range of lighter-duty products on the market, from ultrasonic devices, to motion-activated water sprayers, to various whirligigs and visual "scarers." It's tough to verify the relative effectiveness of these products, however, so if birds are presenting a problem to your corn crop, we recommend experimenting with a few different techniques, and seeking the advice of an experienced local gardener.
When to Harvest
Pests aside, another frequent corn query is: How do you know when to harvest? Well, if you can't or don't want to use Steve's "raccoon method," then it comes down to a matter of corn-grower's touch, which gets better with practice. The key is to feel around the silk-end of the ear; what you're feeling for is that the kernels at the end are as large and well-formed as the ones around the middle of the ear. If not quite, your corn is still a day or two premature; but if so, that means you're ready to harvest. Happy crunching!
You can see this article with photos at:
Victory Garden Corn Care
The WA, OR, & ID Master Gardeners have a insect pest handbook on the web. They list peach, potato, and bean aphids; corn earworm; cucumber beetle; and spider mites. Go to the site below and look for the Home Garden chapter and the section on corn at:
PNW Insect Management Handbook
Irrigation
The Sweet Corn Irrigation Guide from OR State U states:
Irrigation of sweet corn should be managed to supply adequate soil moisture while at the same time maintaining adequate aeration and soil temperatures. In the period between seeding and emergence, low soil temperatures can delay or prevent germination. Thus, it is recommended that fields be irrigated prior to seeding and not again until after emergence whenever possible. In the remainder of the season, available soil moisture should not be depleted by more than 50 percent. Especially critical is the time between silking and harvest. (Corn will exceed the water needs of lawn as it approaches tasseling by 25% and gradully drop to lawn levels at harvest.) Water deficit during this period will have the greatest negative impact on yields. Excessive irrigation, however, may also negatively impact yields by promoting excessive stalk and leaf mass.
The peak water use for sweet corn is approximately 0.22 and 0.18 inches per day for April and June plantings respectively. On most soils, weekly irrigation during the peak is adequate, however with sandy and sandy loam soils, irrigation may be required as frequently as every three days. (Emphasis mine.)
This guide is for field irrigated corn but there is a good chart showing monthly water needs for both April and June planted corn. They state the average seasonal water amount is 17 inches. I simulated growing Golden Jubilee corn in 2004 at Aurora, OR. I sowed in early April and harvested on August 31st and got almost 22” of total water needs. A shorter season variety like Bodacious would have been harvested almost 3 weeks earlier and used 17-18 inches of water. Aurora did receive about 2.5” of water in August 2004 after a dry, warm spring and early summer.
You can see the OSU guide at:
Sweet Corn Irrigation Guide
Particularly in Western Oregon, you can use the daily crop Evapotranspiration (ET) data from the AgriMet sites of the Bureau of Reclamation. Their site map is at:
AgroMet Maps
My TOTW last year goes into great detail on using ET to schedule your garden watering. You can view it at:
Watering Your Garden
The weather radars are showing the bottom end of Vancouver Island as now beyond an inch of rain and it is getting starting to get serious here now so I think I'll curl up with a good book.
We have corn and cover crops coming plus answering your questions.
Gary
Olympia, Sunset Zone 5, USDA Zone 8
gary
Location: Washington, Puget Sound Corridor
Posted: Mar-31-2005 at 5:01am
Penn State has this to say about crop rotation:
Crop rotation
Crop rotation is an important aspect of production that most Pennsylvania corn producers should consider. A carefully planned crop rotation including corn has many advantages over continuous corn. Corn yields often are increased by 5 to 7% following soybeans and up to 10 to 15% following hay. These "rotational effects" often are enhanced in drought years.
Farmers that Penn State was talking about are rotating with soybeans and alfalfa. In his Market Garden, Eliot Coleman used an 8 year rotation as follows:
Year 1 - Potatoes
Year 2 - Squash
Year 3 – Root Crops
Year 4 - Beans
Year 5 - Tomatoes
Year 6 – English Peas
Year 7 – Cabbage Family
Year 8 – Sweet Corn
You can see that he was spreading his vegetable families over 3-4 year cycles (e.g., potatoes & tomatoes; radishes, turnips vs. coles). Each year Eliot was sowing a cover crop into each bed to grow with or after harvest.
I use a 3 year rotation by combining some families:
Year 1 – Potatoes, tomatoes, cucurbits, roots
Year 2 – legumes, alliums, lettuce & non-cole greens
Year 3 – Cabbage family
Year 4 – Corn (if I grew it)
As I put much of my winter garden into the cabbage family, I am reluctant to give up some of that area for corn. If I had to grow my own corn, I might try Reich’s hill system above and transplant the over winter cauliflower and sprouting broccoli between the hills (see Trav’s site for the timing and culture of these Feb/May fresh from the garden gems). These plants should get enough sunlight and you don’t want them to get too big before Persephone time anyway.
Coleman also sowed a soybean cover crop between his corn rows because it inhibits some diseases in the potatoes that follow. He states:
Potatoes follow sweet corn…because research has shown corn to be one of the preceding crops that most benefit the yield of potatoes.
Sweet Corn follows the cabbage family because, in contrast to many other crops, corn shows no yield decline when following a crop of brassicas. Secondly, the cabbage family can be undersown to a leguminous green manure which, when turned under the following spring, provides the most ideal growing conditions for sweet corn.
The Cabbage Family follows peas because the pea crop is finished and the ground is cleared [early] allowing a vigorous green manure crop to be established.
Coleman used white clover as the cabbage under sown green manure. Its low growth and 40F germination temperature would seem to make it a good candidate. As it will also survive Zone 4 winters, he, like us, was not counting on winter kill to prepare the bed for corn planting. White clover can be mow killed the first year and it is easily till killed with home garden equipment (Mantis or by hand). Mowing before you till/chop in will speed the process.
You can see Coleman's and other rotation system at:
An Overview of Organic Crop Production
Seems that we are ready for:
Cover Crops
White clover would be good choice for weed suppression in the corn patch also. For example, the 2nd edition of Managing Cover Crops Profitably, states:
Crop shading. Sweet corn shading can hold white clover in check when corn is planted in 15-inch rows and about 15 inches apart within the row. This spacing yielded higher corn growth rates, more marketable ears per plant and higher crop yields than conventional plots without clover in an Oregon study. Corn was planted into tilled strips 4 to 6 inches wide about the same time the clover was chemically suppressed. Adapted row-harvesting equipment and handpicking would be needed to make the spacing practical.
Maybe good sunlight gardeners should try that 15"x15" spacing? Let us know if you do. As I desperately need to weed my asparagus patch right now, I had to include the next paragraph also:
Unsuppressed white Dutch clover established at asparagus planting controlled weeds and provided N over time to the asparagus in a Wisconsin study, but reduced yield significantly. Establishing the clover in the second year or third year of an asparagus planting would be more effective.
White clover stores more N in its root system than other legumes:
Fixes N. A healthy stand of white clover can produce 80 to 130 lb. N/A when killed the year after establishment. In established stands, it also may provide some N to growing crops when it is managed as a living mulch between crop rows.
Because it contains more of its total N in its roots than other legumes, partial tilling is an especially effective way to trigger N release. The low C:N ratio of stems and leaves causes them to decompose rapidly to release N.
That 80 to 130 lbs of N is about half of the seasons requirement for your corn crop. Incorporating the green manure before sowing would seem to eliminate your supplemental fertilizer feeding or about one-half of the total fert.
For those unfamiliar with Managing Cover Crops Profitably, it is available online in pdf at:
Managing Cover Crops Profitably
Gary
Olympia, Sunset Zone 5, USDA Zone 8
gary
Location: Washington, Puget Sound Corridor
Posted: Mar-31-2005 at 12:50pm
Gary Kline in his latest garden alert passes on some advice on drought actions and using experiments with corn as examples. He wrote:
Governor Gregoire declared a drought emergency.
STRANGE BEHAVIOR - Ever since the Governor’s declaration, there has been at least some rain almost every day. It almost seems like our weather is back to normal. Maybe there should be a recount. I (GK) remember a few years back when we were told there was going to be a drought and the relevant agencies started shouting water conservation; only the drought didn’t come. A number of people decided to give up gardening that year only to find they simply lost a year of good gardening.
OUT ON A LIMB - Now, we’re not going to call the whole thing off and make a lot of people look silly. However, it does seem prudent to repeat the part of our Alert that the Governor left out. Here goes. “Does this mean give up gardening? No, it means gardening smarter. Conserve water, or course; but also do mulch. The smartest way to do mulch is to do ‘Fertile Mulching.’ (Apply fert & water/rain and then mulch, see below.)
MID-COURSE CORRECTION - The March 10 Alert went on to say “Mulching holds in moisture and holds off drought, but one of the smartest things you can do to reduce the effects of drought on plants is to fertilize them well. Research has proven that well-fertilized plants grow bigger and deeper root masses and are far more capable than unfertilized plants at getting down to where the water is available. Also, the plant canopy is bigger or thicker and shades the ground. The result is that you can quadruple your crop yield on less than HALF the water applied compared to one that is poorly fertilized.” Instead of half the water, we should have said slightly more water. The difference could be between losing and wasting the crop and harvesting an abundant crop. Worse things could be done with limited water.
THAT’S NOT ALL - The research referred to above was done on side-by-side corn fields during a drought in Missouri. However, there was no mulching involved. If a good mulch of a few inches depth had been used on the fertilized field, very likely they really could have used only HALF the water as on the unfertilized field and gotten even better than quadruple the production. And the corn would have had far better nutritional content to boot! No reason you can’t do that and show the Governor a thing or two.
P.S. – Of course you want to use an organic fertilizer, or fertilizer blend, and preferably work it into the soil. Apply the mulch after one of those good rains, or else wet the ground well first, then check under the mulch about monthly to see if re-wetting is needed. If so, rake back a “trench” in the mulch down to the soil, fill the trench with water, then replace the mulch and forget watering for a few weeks, then check again. This should be S.O.P. every year.
ANOTHER CORNY DROUGHT STORY – In “The Bio-Gardener’s Bible,” author Lee Fryer tells about a drought in Iowa where an astute farmer saw a heat wave coming and hired an airplane to spray his cornfields with a relatively tiny amount of liquid seaweed (kelp). His corn survived and kept growing while his neighbors’ corn fields dried-up and were lost.
WARNING: This magic bullet only works under the right atmospheric conditions and when the field or garden already has good, basic fertility in place. On the other hand, what do you have to lose by doing an occasional foliar fertilization once the crops are well up? It can do wonders on both food crops and landscape plantings. We call this supplemental fertilizing or feeding “snacks” to your plants. Don’t skip meals.
Steve Solomon raised his corn in his Water-Wise Vegetables recommended growing corn on 3 foot centers or in WA and BC, 2 foot in rows 3 feet apart. Solomon also used foliar feeding as Gary Kline mentions above. With many of his widely spaced vegetable, especially coles, cucurbits, and solans, Solomon used 5 gal. drip buckets of fertilizer/water. He mixed his fert at half strength.
Gary
Olympia, Sunset Zone 5, USDA Zone 8
cjmiller
Location: Oregon, Willamette Valley
Posted: Apr-01-2005 at 4:36pm
Why is it always stated to plant corn in hills? When I first started gardening, I always planted way too many seeds. and had a mess to try to work in the corn patch. In spite of the advise to plant in hills, I thin to one plant every 8 to 12 inches in 4 rows 32 inches apart and havent planted in hills for the past 30 years, Is there a scientific reason for planting in hills, or is it traditional?
Carol
gary
Location: Washington, Puget Sound Corridor
Posted: Apr-01-2005 at 5:21pm
CJ,
Obviously, I did not explain clearly enough earlier. I believe that 'hills' started with the 'pilgrim/indian' culture after Plymouth. They put fish scraps into the ground and sowed beans/corn/squash, "the three sisters", into the hill.
I hope that I explained carefully enough above that "YOUR" spacing will work very well here in the Maritime PNW. Should you wish to 'companion' sow other crops, then 'hills' will allow you to do that. Such as, down at 30/48" wide bed, sow in hills and transplant lettuce in the empty spaces. After you harvest the lettuce when the corn is about 'knee high', transplant winter cabbage family crops and sow white or crimson clover as your green manure.
Gary
Olympia, Sunset Zone 5, USDA Zone 8
cjmiller
Location: Oregon, Willamette Valley
Posted: Apr-02-2005 at 3:20pm
Thanks for explaining because even when I went back over the material again I couldnt find it or didnt get it Duh! So, if it works dont fix it.
Now, about rotation--I have mainly focused on not planting potatoes and tomaotes in the same location in consecutive years and aim to plant this years tomaotes where last years legumes grew, In the 8 year rotation you have a 4 year span between potatoes and tomatoes, but in the second rotation cycle you mention planting families togeter? Why does this seem like a contradiction to me? When you make consecutive corn plantings with the rows running north to south do you start your corn at the the north end and plant consecutive seeds to the south based on the prevailing NW winds? Oh yes, about the taste of corn--We always thinK the first corn of the season tastes the best no matter what variety it is!
Carol
gary
Location: Washington, Puget Sound Corridor
Posted: Apr-03-2005 at 3:17pm
Carol (CJ),
With a RN spouse, I will always defend your need to demand that I explain myself.
For your last question: I would always sow tall crops from the north to the south. Then the later plants will not shade the newer ones. (Except this year, I plan to transplant my July 1st lettuce to the north of my pole beans. The beans will be planted on the south side of an east/west bed. I think/hope that the shade provided by the beans will 'delay' the bolting of the lettuce plants.)
The 8-year rotation is Eliot Coleman's. I split my 12 beds into 3 or 4 bed parcels and put, e.g., tomatoes, potaotes, & roots into 3 of them. With a large garden, I would do the same on 25 or 33% of the garden.
My RN 'made the mistake' (as did Lisa) of marrying an engr. type. There can't be more than two women that have made that mistake in the Maritime PNW and have had to learn how to understand the verbally deficient.
I hope that I have gotten clear enough with these repetitions.
Gary
Olympia, Sunset Zone 5, USDA Zone 8
Lisa A
Location: Oregon, Greater Portland Metro
Posted: Apr-05-2005 at 7:25pm
Originally posted by gary
My RN 'made the mistake' (as did Lisa) of marrying an engr. type. There can't be more than two women that have made that mistake in the Maritime PNW and have had to learn how to understand the verbally deficient.
lol, gary. but i must have learned his lingo - and he has learned mine - because we seem to do okay. i guess it's a 'mistake' i'd do all over again.
this wonderfully-informative totw is no longer 'sticky' [programmed to stay at the top of the forum] but that doesn't mean the discussion must end. gary will continue to share his wealth of knowledge and answer questions. in addition, we all learn when others share their experiences and gardening skills so please don't be shy about contributing to the thread.
thank you, gary, from all of us at rainy side for hosting this topic on corn.
Gardening requires lots of water - most of it in the form of perspiration. - Lou Erickson.
Gardening for the Homebrewer: Grow and Process Plants for Making Beer, Wine, Gruit, Cider, Perry, and More
By co-authors Debbie Teashon (Rainy Side Gardeners) and Wendy Tweton