How to Grow Corn in Raised Beds: A Complete Guide

Corn, or maize, is one of the oldest crops cultivated by humanity. Dating back 8,000 years or more, it is a staple for summer barbeques and the backbone of many cuisines. From sweet corn to popcorn to flour corn, there are thousands of varieties. While many think that growing this crop requires massive amounts of space and big equipment, the truth is that most varieties can be grown right in your backyard in a raised bed.

Let’s dig into everything you need to know about growing corn in raised beds.

Can You Grow Corn in Raised Beds?

Raised beds are a great option for small-space cultivation. This crop is best directly sown in full sunlight with a grid-shaped planting to ensure proper cross-pollination. Corn is a grass-family crop that works excellently with vegetable crop rotations and thrives in warm weather.

A short raised bed is perfect since the roots are fairly shallow, reaching only about 12 inches deep into the soil. The key is to plant the right variety, provide consistent moisture, prevent cross-pollination, and harvest the ears at the right time.

Here are more simple tips to amazing backyard yields:

8 Steps to Grow Corn in Raised Beds

You can grow this crop on a tiny scale as small as a 3×5 foot bed. A short raised garden bed around 15-18 inches deep is the perfect depth for this shallow-rooted grass. This guide includes everything you’ll need to prepare the soil, plant, tend the crop, and harvest sweet cobs for the grill. 

Choose the Right Variety

Sweet corn is the most popular for home cultivation because you can grab an ear, husk it, and grill it up for a classic summer treat. 

Dent corn is the most common type grown commercially on a massive scale, but dent varieties are not desirable for fresh eating. Instead, it is used for things like tortilla chips, corn syrup, and cornmeal. In contrast, sweet corn is specifically bred for eating like a vegetable. You must harvest it at the right time before the seed kernels begin to mature and dry. Popcorn varieties are left to dry on the stalk, and then the kernels can be removed for popping.

You can grow multiple types, but it is very important to plant them in separate parts of your garden. Preventing cross-pollination is particularly crucial if you grow sweet corn and popping varieties in the same yard.

Choose a Full Sun Site

Corn absolutely requires full sunshine to thrive. This grass cannot grow in the shade. Be sure to use a south-facing or west-facing raised bed that receives six to eight hours (or more) of direct sunlight every day. Do not plant where trees, shrubs, or structures may shade the crop. 

Corn that isn’t receiving enough sun may demonstrate these symptoms:

If your garden does not get very much sun in the morning or afternoon, you can try pruning back trees and growing extra tall varieties that can reach over the shade of fences or shrubs. When in doubt, choose the brightest area possible.

Prevent Cross-Pollination

Why it Matters

If you plan to grow multiple varieties of corn, separation by time or space is crucial for success. It is a unique crop because it shows cross-pollination issues in the same year as planting. This is because what you are eating (the kernel) is the seed itself. In other words, if a sweet corn variety crosses with a popcorn, the resulting fresh-eating cobs may not be as sugary or tender because they will have the genes of the popcorn plants.

Corn is a member of the Poaceae (grass) family. It produces long tassels that contain pollen to fertilize neighboring plants. We’ll explain more about silks and tassels below. Because it is pollinated by wind, the seeds are typically planted in blocks to facilitate pollination, ensuring cobs full of plump kernels. Different cultivars need to be spread about the garden or sown at different times to ensure that they only pollinate with their own kind in the same block or bed. This is a key difference between corn and many other vegetable crops.

For example, you can plant many types of peppers in a small space in your garden, and they will naturally cross-pollinate. However, the fruits will remain the same variety as you planted; only the seeds will be hybridized. If you planted shishitos and jalapenos in a bed together, and they somehow crossed, each plant would still yield its usual peppers, but the seeds would yield differently if planted the following year. 

In this case, if you’re not saving seeds, you don’t need to worry about cross-pollination. But with corn, you are eating the seeds, and the flavor and texture will be altered in the present growing season. Isolating different varieties from each other is key.

How to Prevent Cross-Pollination

Don’t let this deter you from experimenting with multiple cultivars! Here are a few ways to prevent cross-pollination:

Planting may require a bit of experimentation, but it is always worthwhile to test different cultivars. In the absolute worst-case scenario, you may end up with a funky hybrid between two types. This could be a new flavor or color you’ve never tried before! 

Prepare Your Raised Bed Soil

Corn roots only reach about 12 inches deep in the soil. A short mounded or raised bed is great for ensuring adequate drainage and soil texture. It’s best to prepare the soil in advance by mixing in a generous amount of compost or quality topsoil. If your raised bed is already established, simply remove any weeds, topdress it with compost, and loosen the soil as needed. 

Loose, loamy soil is ideal to provide the organic matter and fertility this crop loves. Mix in an all-purpose organic fertilizer before planting to fuel growth. This grass is a heavy nitrogen feeder that requires a lot of nitrogen to initiate growth. Blood meal (12-0-0) and cottonseed meal (6-2-1) are great options for slow-release fertilizer. Organic products are best to ensure the purity of your food crop and to prevent fertilizer burn. Sprinkle the fertilizer in each planting hole or follow the package recommendations to measure and amend the entire bed. Synthetic nitrate fertilizers are not recommended because they can easily overdose the crop and quickly leach out of the bed.

Direct Seed or Transplant

Unlike many plants in the garden, most of us recognize corn seeds because they are actually the part of the plant we are eating. Direct seeding is recommended because corn is a grass that prefers to establish its roots in the location where it will grow. 

However, transplanting is perfectly doable and most desirable for growers in zones 5 or colder due to the very short growing season. You can start with Epic 6-Cell Seed Starting Trays, soil blocks, or even a recycled tupperware dish.

Direct Seeding

Sow outside one to two weeks after your average last spring first date. The soil temperature must be at least 60°F (16°C), and ideally closer to 80-90°F (27-32°C). This warm-season crop will not germinate in cold soils. If you are unsure, use a soil thermometer probe to check your beds.

Prepare a clean, weed-free soil surface in your raised bed. Use a tape measure to plan out the grid and proper spacing. Most varieties are best spaced 10-12 inches apart. This means there should be about one square foot of space around each plant.

Corn is planted in blocks or beds because it is wind-pollinated. As the plant matures, it will produce a tassel, which is the male part of the plant where pollen is produced. Lower on the stalk is where the silks, the female part of the plant, develop. The pollen must fall from the tassel to the silks to properly pollinate each kernel inside the cob. If there is poor pollination, a cob may not have its full volume of kernel grains. 

Pollination mostly happens from the wind. Ideally, you should plant in a large square raised bed or in two rectangular beds right next to each other. The wind ensures that the pollen has a better chance of hitting each silk. Plant one variety in two square or rectangular blocks that can cross with each other. Remember to label and separate other cultivars.

Sow the seeds one half inch to one inch deep and gently press the soil on top. Water thoroughly. Wait 5-10 days for the plants to germinate and thin out any extra seedlings to ensure 10-12 inches of space between every plant.

Starting Indoors and Transplanting

If you want to start indoors, seed around one week before your last frost date and transplant outside while seedlings are still young and no more than two to three weeks old.

Fill a container with a seed-starting soil mix. Bury the seeds at least one-half-inch deep in the tray. Some people think they need to soak the seeds because the seed coat is so tough. While this can be helpful, it is unnecessary as long as you plant the seeds deep enough. 

Use your finger to poke the planting holes and add one or two seeds per cell to guarantee germination. If you plant two seeds and they both germinate, you will need to thin to one plant per hole. Thinning is crucial for crop success. If two plants grow too close together, both will probably fail to produce quality cobs. After germination, use small shears to snip off the less vigorous seedling at the base.

Gently cover the hole, water generously, and wait 5-10 days for the seedlings to emerge. Transplant corn a few weeks later when the weather is thoroughly settled. Plan your grid or block with at least three rows planted 10-12 inches apart. Each plant needs about a square foot of growing space. Do not plant them all in one single row. Clustered blocks are necessary for pollination.

Provide Consistent Moisture

This crop is not very drought tolerant. It has shallow roots and needs consistent moisture throughout the growing season. Water generously after planting and keep the soil moist, but never soggy, for the entirety of the growth cycle. Ideally, this bed should never dry out. Plants especially need extra moisture during the first few weeks of growth.

Overhead irrigation is fine, but drip lines conserve more water and prevent disease by delivering moisture straight to the root zone. Water initially with a hose and switch to drip irrigation after the first few weeks.

Before irrigating, stick your finger several inches deep in the soil to check the moisture level. It should feel like a wrung-out sponge. The soil should slightly stick to your skin. If your skin comes out dry and clean, the bed is likely too dry. If the soil feels mucky and covers your skin in mud, it is far too wet, and you need to let it dry out.

Mulching

Mulching is very helpful and highly recommended. Finely shredded straw mulch is ideal for conserving moisture and suppressing weeds. If you live in a hot area, corn beds can dry out very quickly. A couple of inches of straw mulch makes a huge difference by reducing the drying effect of UV rays hitting the soil surface. If you’re using drip irrigation or soaker hoses, run them underneath the mulch to ensure that the water directly reaches the soil to soak into the root zone. 

Take note that earwigs sometimes attack seedlings. These nasty bugs can hide in mulch and munch down on young plants. Straw is the perfect environment for earwigs to thrive. If earwigs are a problem in your garden, you may want to hold off on mulching until the corn is about one foot tall. Once the stalks are established, it is safe to mulch the bed.

Companion Plant

Corn can benefit from companion planting just like most other veggies in your garden. However, it’s very important to select companions that won’t compete with corn’s high nutrient needs. Moreover, many crops cannot handle being shaded out by giant corn stalks. Avoid planting corn in beds with nutrient-hungry, vigorous plants like tomatoes, peppers, brassicas (kale, broccoli, etc.), or rhubarb.

The best companions for have complementary growth habits. Pole beans are a very popular companion because they can ramble and vine up the corn stalks. This is common in the traditional Three Sisters Native American planting.

Squash is another awesome comrade because it rambles low to the ground and acts like a living mulch. The big, broad leaves of squash shade out weeds and keep the soil moist. Moreover, squash won’t compete with corn as long as it has 12-18 inches of space from the plants. 

Melons, nasturtiums, pumpkins, and borage are also excellent ground cover options near corn. Notice how all of these plants have broad foliage. Their wide leaves and stout growth habits complement corn, and they won’t mind the dappled shade of the stalks.

Whatever companion plant you choose, be sure there is sufficient space between plants, and add additional water to keep all the crops in the bed hydrated.

Harvest at the Right Time

Corn takes 60 to 100 days to mature. The plants begin forming silks and tassels 9 to 10 weeks after germination. This is a critical period of reproductive growth that determines the success of your crop. Tassels are the funky spikes at the top of the plants. These male reproductive organs look like long spikelets of flowers. They hold anthers and pollen that must drop into the silks below to fertilize them.

Silks are the female part of the plant, named for their silky texture. They look like soft green or yellowish-gold hairs that form lower on the plant stalk. Each silk has the potential to grow into a full ear as long as it is fully pollinated. Generally, each stalk only yields one ear of corn, but some late-maturing varieties yield two ears. Sometimes, a plant produces multiple offshoots from the base. 

The first sweet corn cobs usually develop about 20 days after the silks appear. Once the silks are pollinated, they begin drying up, and the cobs become firm. The easiest way to prepare for proper harvesting is to track the days to maturity in your calendar. Mark your seeding date and create a reminder 60-70 days later to check the corn. You can also create a reminder to check on them three weeks after tassel formation.

Test for Ripeness

Ripe ears feel full inside their husk. Squeeze the top to feel for a full formation. The silks will be brown, dry, and withered. If you can easily pull the silks off, the ear is likely ready. Snap or twist off each ear and peel back the husk to check its ripeness. Poke an upper kernel with your fingernail to test it. If it is slightly soft and exudes a creamy white fluid, you are ready to harvest! Test one cob first to determine if the rest should be pulled. 

Enjoy grilled, boiled, roasted, or in your favorite recipes!