Common Problems Growing Sweet Corn in the Home Garden

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Is there anything better than fresh sweet corn on a hot summer’s day? (Well, maybe fresh-picked watermelon.) While I didn’t always grow sweet corn, once I started, it quickly became a family favorite and has earned a staple spot in my garden.

Getting corn to a full harvest sometimes presents challenges. Whether you are considering making room for corn in your garden or you’ve been growing it for years, it helps to know what troubles await and how to deal with them ahead of time.

On the most recent episode of the Beginner’s Garden Podcast and the article below, learn the most common problems home gardeners have with growing corn. Listen to that here or keep reading.

Common mistakes when planting corn

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Not planting enough

One of the biggest mistakes you can make in growing corn is simply not planting enough.

Corn is wind-pollinated and each kernel must be individually pollinated in order for it to develop. This requires devoting more space to corn than a beginning gardener usually realizes. At a minimum, you want to plant four rows of corn, though the more the better. I get my best pollination in plots that are 4′ x 25′ long.

You also want to devote enough space to corn for a different reason. Each corn plant only produces one large ear. In the best of seasons and with ideal conditions, you may get a second smaller ear to develop after the large ear, but this isn’t always the case and shouldn’t be counted on.

corn seedlings about a foot tall

If you have a small garden, it can be hard to add corn to your garden plan, as the space required for successful growth is large compared to other crops. It is something you have to really think about and weigh the advantages and disadvantages to adding it to your garden.

Poor germination

Most gardeners sow corn seeds directly into the garden. If the soil temperature is warm enough (65F minimum), corn germinates quickly and uniformly. But if you notice that your sprouts lack consistency, there could be a few reasons.

Birds and Sprouts

The most common reason for spotty germination for my corn plantings is that the birds love corn. They’ll steal seeds and sprouts in short order! Sometimes I sow extra corn to offset the snacks the birds feast on. But there are other options.

You can add a string 6 to 12 inches above the ground between two stakes from the start of your row planting to the end. This deters our feathery friends from getting to the seedlings.

You can also start seeds ahead of time indoors, in a greenhouse, or even outside in seed trays. Then, when the sprouts are 4-6″ high, they can be transplanted into the garden. This allows them to be planted at the correct spacing (9-12″ apart) and usually the sprouts are large enough that the birds don’t bother them.

transplanting corn

Types of Corn and Germination

Supersweet types of corn, unfortunately, don’t germinate as well as others. That’s something to keep in mind. If that’s your preference, just plant more to combat the germination risk.

Soil Temperature and Seed Depth

In the early spring, make sure you plant when the soil is warm enough — a minimum of 65F. Also, don’t plant too deep, since the warmer soil will be toward the surface in the early part of the season. Planting corn seeds at a depth of one-half inch will aid in quick germination.

As the season progresses, you may want to plant a succession planting of corn. For a mid-summer planting of corn when the weather is hot and rain is sparse, plant the corn seeds at a depth of one inch. This will help keep the corn seeds and sprouts from dying out before a strong, deep root is established.

jill in her corn field

Soil Requirements for Corn

If your corn seeds sprouted well, but they are struggling to grow, it could be an issue with the soil, nutrients, or water — or a combination of any of these. Let’s explore what can go wrong when corn is growing in our gardens.

Compacted Soil

Corn, like other vegetables, thrives in loose, friable soil. If the soil is compacted, the seedlings struggle to get established. Corn has a deep, expansive root system, and compacted soil will hinder its growth underground, which you may see also aboveground.

Improper pH

Like other garden vegetables, corn will grow best when the pH is optimal for its growth. It actually tolerates a fairly wide range — anywhere from 5.8 to 7.0 is desirable, but outside those parameters, it may struggle. If you suspect a pH problem, I recommend a soil test.

young corn growing in rows

Not enough nitrogen

Corn is a heavy feeder of all nutrients but particularly nitrogen. Make sure you add compost and an extra nitrogen source prior to planting. I like to use my composted manure from my chickens or Garden Tone.

Another way to naturally add nitrogen to your soil is to plant legumes (like beans or peas) in the same space both prior to and along with your corn plantings.

When the corn reaches about 18 inches in height, feed them again with nitrogen-rich fertilizer. For an organic gardener, you may choose a slow-release granular fertilizer like blood meal or a liquid option like fish emulsion.

Not enough water

Just like corn loves nitrogen, it loves water just as much. Make sure the soil stays moist during its entire growth, but this is of utmost importance from the time your corn has tassels forming through harvest.

corn tassel

In my garden, corn usually begins to develop its tassels during our driest spells. If you find this to be the case as well, make sure you keep watering. I prefer to use drip irrigation set on a timer to water every couple of days.

If your corn is fighting weeds in an area, the weeds can also rob the corn’s water supply. It’s best to make sure your corn area stays free of weeds as much as possible to help keep that soil moist below. A thick layer of mulch will go a long way here for both weed suppression and water retention.

Strong winds

Just when your corn starts to tower in your garden, strong winds can knock over even the tallest corn stalks. If you live in an area where the wind is common, you may want to consider running a string up between t-posts to help support those plants as they grow.

Cornstalks blown over from strong winds

You can also companion plant with pole beans, which will help the root structure become a little more stable underneath the soil. The root systems of the beans planted around the corn helps anchor the corn stalks.

Problems When Harvesting Corn

You’ve made it! The corn is ready to harvest. Sadly, this is the area where I’ve struggled the most. Here are a few things that can go wrong when harvest time comes.

Not harvesting at the right time.

A super common mistake with harvesting is the timing of when you harvest. Start looking to harvest about 20 days after your silks appear. The silk is located at the tips of each ear.

corn silks starting to turn brown
Fresh silk emerging from corn cob — pollination is beginning.

From here, you want to watch for the silks to turn brown and dry out completely. They will slough off easily.

dried corn silk ready to harvest
dried out silk on corn cob — pollination is complete.

The corn will also start to bend away from the main stalk as it nears maturity.

Once you observe these signs, you can test an ear by peeling down the leaves at the tip of the husk about half-way to expose the kernels in the middle of the ear. Now, you’ll use your thumbnail to prick one kernel.

If a milky white fluid comes out, this is the perfect time to harvest. If the liquid is clear, this means that your corn is not quite ready. Lastly, if you prick the ear and a thick, gum-like texture emerges, it means your corn is past its prime and you’re best feeding these to the birds (or chickens).

In my first year, I lost my entire harvest because I waited too long to harvest. The ideal window is very short (as in a few days). So, make sure you are watching your silks. If they start to brown and they are dry, this is when your ideal harvest will be. In the video below, I demonstrate when corn is ready to harvest:

Missing Kernels or Small Ears

If you go to harvest your corn and you notice that the ears are smaller than expected, or worse, they are large but many of the kernels haven’t formed, there are a number of reasons this could have happened.

corn ears missing kernels

Lack of pollination

One of the reasons is what we mentioned above — not planting enough for complete pollination. Because each individual kernel has to be pollinated, this requires a lot of pollen to fall to ensure that this happens.

Weather Conditions

If weather conditions are hot and dry while your corn is growing, you may find that the tops of your ears are not completely pollinated, while the rest of the ear looks fine. In this case, chances are it’s the weather. With limited resources, the plant focuses on pollinating the middle and bottom kernels first, leaving the top ones for last. There’s not much that can be done about that besides making sure you water well.

Plant Spacing

One reason for small is that you planted the corn too close together. Their ideal distance for pollination is between 9 and 12 inches apart. When they are crowded together closer than this, resources in the soil (both water and nutritional) can’t supply all of the plants.

Potassium Deficiency in Soil

If you find that you’ve done every single thing right and the corn ears still didn’t reach their potential, the problem could be a potassium deficiency. Again, a soil test can easily inform you if this is a problem and you can correct it before your next planting.

a lot of corn ears

Corn earworms

You’ve harvested all your corn and you’re now ready to move on to shucking the corn. You start to peel just to discover that there’s a live little worm inside! Is it gross? Yes. Does it happen often? Yes. Unfortunately, these little worms love corn as much as we do!

Corn earworm problems begin when the moth lays eggs on the silks at night. Then they develop into worms and crawl inside the husk and start eating the corn kernels.

corn earworm eating tip of corn ear

What can you do about the corn earworm? Personally, I just break off the tip (worm included) and feed them to my chickens and then go on about my harvest as normal.

If you find that earworms are more problematic than you want to deal with, check the variety that you plant and see if you can find one more resistance to the earworms. Some varieties have tighter tips, which deter earworm damage more.

You can also test different planting times. From my research, I’ve learned that earlier spring plantings are not as affected, generally, though, in my garden, the late summer plantings with September harvests have been the best times for me.

Test different planting times and different varieties to see if you can find a ideal planting time for your climate and a variety that is more resistant.

an ear of corn with stalk still on

Final Thoughts

My hope is that this article has prepared you for what to expect when growing corn. As we conclude, I wanted to share some other thoughts regarding growing corn in your garden — or not.

First, consider planting corn as a succession crop. If you have a long growing season, you could plant several plantings. Sometimes I plant one in April, one in June, and one in July.

You could also plant later in the summer after a cool weather crop has harvested, in that same space. Corn is a great succession crop to plant after peas, for example.

Also, try growing different varieties. If one doesn’t work for you, there are many others to consider.

Lastly, consider if it’s worth your space. If you have a smaller garden, but you really love sweet corn, visit your local farmers market. This is the ideal place to get that sweet corn craving satisfied while supporting your local friends and farmers.

corn ready for harvest

No matter if you’re new to growing corn or if you’re a seasoned gardener, hopefully, you’ve learned something that will benefit your next harvest.

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2 Comments

  1. Hi Jill, Nice article! I do grow corn in my garden, usually 6-7 rows (garden is 20 x 30 I think) crosswise. I’m not sure I understand about putting up the strings to deter the birds. Is that between each row or just on two sides running parallel with the rows?
    Also you mentioned planting beans with the corn, what type of beans, pole? I’ve never grown pole beans, only bush beans and have good luck with them except half way thru the season I start to get lots of brown leaves and then they fall off. I think it’s some kind of disease but not sure what it is. We live in zone 4. I still seem to get a good harvest though.
    Keep up the good work, I enjoy your newsletter.
    Nancy

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