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How to Grow Corn in Your Backyard Garden!

According to the National Agricultural Statistics Service (NASS), corn is the largest crop grown in America, covering over 92 million acres! Of course, much of big agriculture's corn is monocultural GMO, not the kind we want to eat. But as home gardeners, we can take control of our food supply, growing corn right in our backyards. Although it's common to grow vegetables in conventional plots, what about in urban garden settings?

Homegrown sweet corn is so delicious and satisfying. Some people are surprised at how easy it can be to grow, even in small spaces. Conventional wisdom dictates that you need lots of space for growing corn. But that's simply not true. You can even grow corn in pots or containers! I've been growing corn for years, with great success. Let me share my tips for growing large, sweet corn.

How to Grow Corn in Containers or Totes

CONTAINERS: If you're a renter, or simply live in an urban area, you might wonder if you can grow corn in pots or containers. Absolutely! But you need the right sized pot. If you're serious about getting a real harvest the container needs to be at least 12 inches deep, but 16 inches is preferred. Don't restrict yourself to a 12 inch wide pot. The narrow portion at the base needs to be 12 inches. But that translates into a large 18 inch pot. A 16 inch deep, 18 inch wide pot will require nearly 2 cubic feet of potting mix. That's the MINIMUM you need for structural stability as well as adequate root space. This includes the ability to maintain consistent moisture levels.

Do not use 12 inch wide containers! Corn gets pretty tall. Even when you select a dwarf variety, it can still get top heavy. A 12 inch wide container does not have a wide enough base to prevent it from tipping over in the wind. The small amount of potting mix will get quickly depleted of nutrients. And as the corn stalks get tall, your pot will be constantly running out of water. This will reduce the quality of your harvest. In a properly sized 2 cubic foot pot, expect to grow 5 or 6 corn plants.

30 GALLON TOTES: Growing corn in 30 gallon totes will provide a modest upgrade over traditional containers. Totes are pretty cheap and will have a more stable base. You can even create a water reservoir, making them into self-watering containers: 30 Gallon SIP Tote. Expect to grow around 11 corn plants in a 30 gallon tote.

How to Grow Corn in Raised Beds or SIPs

RAISED BEDS: Growing corn in raised beds is very simple. Since raised beds are traditionally set up so that you will not step in them, they cannot get too wide. Most people can reach about 2 feet into a bed to access their plants. So don't make the bed any deeper than that, unless you have access from both sides. If so, the maximum recommended depth is 4 feet. The bed can be as long as you'd like. It could be a 4 foot x 4 foot bed. Or it could be 12 feet long or more.

Plant the corn in blocks. Rather than 1 or 2 long spanning rows, create shorter rows placed alongside each other. In a 2 foot wide bed, I'm able to squeeze 3 staggered rows of corn. For a 4 foot wide bed you could easily fit 5 rows or even up to 6. But don't go any tighter or the corn might not get good pollination.

SELF-WATERING PLANTERS: If you want to achieve the maximum harvestability, try growing your corn in a: Sub-irrigated Planter. The same spacing applies as with raised beds. But sub-irrigated planters (SIPs) have the added advantage of a huge water reservoir. This conserves water and makes it much easier for you to water your plants. If the corn has good light exposure and plenty of nutrients, it will be able to grow to its maximum potential. As the kernels form, there won't be any issues caused by restricted water access.

Which Sweet Corn Variety to Choose?

One thing that's pretty important, is to pay attention to the type corn you're ordering. Some types are suited for popcorn. Some, like flint corn, may be ornamental. Dent corn, aka grain corn, might be used in cornmeal flour or tortillas. For fresh eating, you want SWEET corn! Sweet corn varieties can maintain their sweetness longer because they're not as quick at converting their sugars into starches.

As it just so happens, there are three basic sweet corn genes: SU is known as "sugary." It has a short shelf life and should be cooked as soon as it's picked. This type is better adapted to cool conditions. SH2 is called "supersweet." They have even higher sugar content and can be stored for several days in the fridge before cooking. SE refers to "sugar extended." It also has higher sugar content and will maintain its sweetness even longer. The plants are better suited for warm growing conditions. This can help to select the genotype that fits your growing conditions. Something to be aware of is that some sweet corn cultivars may have 2 or even all 3 of these genotypes!

Harvesting Large Ears of Homegrown Corn-on-the-Cob from My Garden
My personal favorite is "Incredible" corn which yields very large sweet ears!

Now it's time to select a specific sweet corn cultivar that suits your needs. Do you want yellow corn, or white corn? Maybe you feel adventurous as you reach for a packet of bi-color corn like "Delectable". If you have a short growing season, you might consider a variety that requires less days for maturity such as "Natural Sweet" (73 days). For container plantings, you could opt for smaller breeds including "White Midget," "Golden Midget" or "Midget Hybrid." My personal favorite is "Incredible" corn (84 days) which gets pretty tall and produces 9.5" ears.

One final note on seed selection. You might notice that some varieties are "hybrids" while others are "heirlooms." Either option is perfectly acceptable and will work with organic practices. For practical use, the key difference is that heirloom seeds can be saved from your crop and then used the next year. With hybrids, there's a good chance that the offspring seeds will produce plants that don't match the parents. It's not an issue if you intend to order new seeds the next year.

Video: How to Grow Corn in
SIP Self-Watering Containers (wicking totes)
Urban Garden Style!

You can get a nice harvest of sweet corn from just a few 30 gallon totes!

How to Grow Corn From Seed

Although you could try to find corn seedlings at a nursery or garden center, it's best to start your garden corn yourself, from seed. Corn needs warm soil to be able germinate properly. Soil temperatures should be a minimum of 50° F after any danger of frost has passed. For some varieties, the recommended temperature range is 60-85° F. The five day forecast should indicate warm temps. This is important because if corn seeds are planted in cool conditions, they may suffer chilling injury. If they absorb cold water, they may be deformed with "corkscrewing." It's better to wait until things warm up so you can ensure proper seed emergence.

One easy way to boost your success rate is to plant 2 or 3 seeds in the same hole. Some seed packets may provide more seeds than you need anyway. This would be a good way to combat issues with spotty germination. Let all of the seeds emerge. Then once the corn 4 inches tall, you can thin out the weaker seedlings by carefully snipping them at the ground with scissors. Don't yank them out, or you'll disturb the roots of the adjacent seedling.

Technically, you could try pregerminating corn seeds indoors in some cell packs. It's more labor intensive. But if you don't plan on growing many plants, and you are anxious to get things going, it might be worth trying. I would not allow the plants to get too big before planting outside though, perhaps 4 inches tall. Be sure the soil and weather is warm enough before transplanting. Raised beds and containers are great options because they warm up faster than the inground native soil. A sunny, south facing location can yield earlier growth and harvest.

How Deep to Plant Corn Seeds?

Some seed packets will state a planting depth of 1 inch. This is an absolute minimum. I've done this and the plants grew just fine. However, in recent years I've actually begun to plant them a little deeper. There are several factors to consider when determining your planting depth including soil temperature, moisture and texture. In the Spring, soil warms from the top down. So if you are trying to rush things along, the deeper you go, the cooler the temps may be. As you go deeper, the moisture content will increase as well. Contrary to seed packets, some farmers may plant as deep as 3 inches!

If you have a large, unwatered field, 2.5 - 3 inches might be needed to ensure that the seeds don't dry out. For home gardeners though, we can just water the seeds. Still though, if your soil is light and sandy, it might be worth planting on the deeper end. A depth of 3 inches can help to ensure that the roots are better anchored as the plant develops. For a very heavy textured soil, 2 inches might be more suitable. In my sub-irrigated raised bed, I've been planting at a depth of 2 inches. The plants are better rooted, which is important in a loose potting mix substrate.

How Far Apart to Space Corn?

Traditional farming techniques will call for some very generous spacing between corn rows. Seeds may be spaced from 8 to 12 inches apart. The rows may be spaced at 24 to 36 inches. This represents what you may envision when you picture a conventional corn field. This works great. But some gardeners are surprised to learn that corn can be planted much more densely in small mounds or blocks.

High Density Corn Growing in Backyard in 30-Gallon Tote vs SIP Raised Bed
After enjoying a good corn harvest, I upgraded my SIP totes to a large SIP raised bed.

Corn needs to be grown in a bright spot with full sun exposure. If you ensure that it's not shaded out by other plants, you can easily grow it in dense plantings. In a single 30 gallon tote, I've successfully grown 11 corn plants in a 4-3-4 pattern. Within a 24 inch wide area of my SIP raised bed, I managed to squeeze 3 full rows. That works out to 40 corn plants within a 2 foot by 8 foot block!

Corn is pollinated by wind and gravity. The pollen falls from the tassels and lands on the silk. Because of this, the plant fares better when clumped in patches. The worst thing you can do is arrange all of your plants into a single long row. Much of the pollen will blow away, never falling on the silk. Thus, you'll get incomplete pollination resulting in cobs that are small an don't have many kernels. This can also result if plants are too tight. But in small clusters, I've gotten full size ears with 6.5 inch seed spacing in staggered rows that are 7 inches apart.

How to Fertilize Corn Plants

If there's one thing every grower will tell you, it's this: Corn LOVES nitrogen. But exactly how much should you apply? Agricultural universities will advise you to determine fertilizer rates based on soil test results. This makes sense for farmers who have massive fields and want to apply only as much fertilizer as needed. But this isn't practical for home gardeners. Soil tests may not even indicate how much nitrogen is needed. And if you do get guidance, it's unlikely to apply to high density plantings in an urban garden.

Some sources advise adding manure to your plot in the Fall. Or you can apply a rich compost several weeks before planting. Then you can side dress with a high-nitrogen fertilizer after plants have reached 2 feet tall. Some growers will spread the fertilizer evenly over the soil, working it into the top 3 or 4 inches. But fertilizer banding is preferred over broadcast applications.

Fertilizing Garden Corn Grown From Seed in Wicking Bed
I bury bands of fertilizer right before planting time and my corn seeds germinate fine.

How much fertilizer should you use for corn though? Conservative recommendations say 2 to 3 pounds of 10-10-10 per 100 square feet. On the other end of the spectrum, I grow my corn in very high density plantings. My backyard garden corn grows in a large wicking bed. Every Spring I apply 10 pounds of 5-3-3 organic fertilizer over 16 square feet. This grows forty 8 foot tall plants. I mix 4 pounds directly into the soil surface. Then I side dress with 6 pounds in 3 bands at the time of planting. And that's it. I don't add any more for the rest of the season.