Corn is one of the edible plants you can grow, whether outdoors or in a container. But while growing some I found that a plant is turning yellow. I wanted to do some investigation to find the problem and a solution.
Your corn plants are turning yellow due to lack of sufficient water. Other reasons the corn leaves may turn yellow include overwatering, lack of nutrients, over-fertilization, pests, or diseases. Some of these problems can be reversed with addition of nutrients and right watering.
Of course, you will probably need to complete a process of elimination to determine which of these causes is the root cause for your corn plants yellowing. While there are several ways to complete this process of elimination, it is important to use your common knowledge to best inform your direction. To learn more about how to help your yellowing corn plants, continue reading.
1. Lack of water
Lack of water is one of the common reasons for plants to have yellowing leaves, including corn plants. The lack of moisture means the plant cannot absorb the required nutrients from the soil. The lack of nutrients will then cause the leaves and stem of the corn plant to turn yellow as a symptom.
You want to ensure the corn plants get the required moisture from the soil. Watering the soil regularly is the best way to achieve this.
You can find out if the soil lacks moisture by sticking your finger 2-4 inches into the soil. If the finger comes out completely dry with no soil sticking to it, it means the soil has turned dry and lacks moisture. You simply give the soil a good watering to bring back the moisture levels.
If the soil has been dry for several days, it may become hard and unable to absorb the moisture. I suggest using a trowel and gently turning the soil around the base of the plant. Make sure not to damage the plant roots when doing this.
You can use a watering can and give a good watering to the soil. Wait for a few minutes and again water the soil. Do this 3-4 times as this will help the soil regain its moisture absorbing capacity after it has turned too dry.
It’s easy to prevent dehydration in the corn plants by regularly watering the potting soil. I recommend checking on the soil every morning. Stick your finger 2-4 inches into the soil and check if it comes out dry. That’s the time to give a good, deep watering to the soil.
If you have many corn plants and can’t find the time to water them, you can use an automated system with a drip irrigation and timer to water the plants on the regular schedule.
Corn plants tend to start turning yellow when they aren’t getting enough nutrients from the soil, typically this is due to lack of nitrogen. You can prevent this by feeding your corn plants with a high nitrogen fertiliser every 2 – 3 weeks. A thunderstorm also helps plants that need nitrogen, so if you live in an area more prone to them, your corn (and other plants like tomatoes and chillies) will flourish. – Sally at All That Grows
Overwatering is a problem beginners can face as they overcompensate lack of watering. You may feel that giving the corn plants a lot of water will do good for them.
The problem is that overwatering will keep the soil moist and suffocate the plant roots. They cannot get the required aeration from the soil as it’s always filled with moisture.
The problem is made worse because the moist environment attracts fungal problems such as root rot. The roots decay and are further unable to absorb moisture and nutrients from the soil.
The symptom of overwatering is like dehydration, where the corn plant leaves will turn yellow and wilt. You can see that the wilted leaves are limp when the problem is overwatering.
Check the condition of the soil to figure out if it’s overwatering that’s causing the problem. Stick your finger 2-4 inches into the soil and check that the soil is sticking to it.
The first thing to do is to avoid any further watering of the soil. You want to make sure it completely dries out before you water it again.
Dig into the soil to check if the roots are healthy or suffering root rot. You’ll see the roots turning brown, soggy, and smell. Healthy roots will be white and dry.
If there are still some healthy roots, you can cut off the brown, soggy ones so the plant can try to recover. If all the roots have turned soggy, you can’t help the plant and it will eventually die.
Once you have trimmed the soggy roots, you can cover up the soil and let the plant recover on its own. Prevent watering the soil or adding any fertilizer to it until the plant has recovered, and the soil has dried out.
You want to water the corn plants on a regular schedule. But only when the soil has completely dried out. I suggest checking the soil every morning as part of your schedule.
Stick your finger 2-4 inches into the soil and check if soil is sticking to it when you take it out. You need to give a good watering to the soil only when the finger comes out completely dry with no soil.
3. Nutrient deficiency
Nutrient deficiency is one of the most likely causes of your corn plant turning yellow. While a healthy corn plant will remain green on the stalk, a nutrient-deficient corn plant will show discoloration in a spotty, streaky, or relatively solid spread in discoloration.
The deficiency can be because of a lack of nutrients such as nitrogen, potassium, sulfur, or zinc, causing the leaves to turn yellow.
The corn plants lack sufficient potassium if the leaves show yellowing at the tips on the older leaves at the bottom. If left untreated, the remaining parts of the leaves will turn yellow and brown as they die.
If the corn plants lack sulfur, the new leaves at the top will show a greenish-yellow discoloration.
Lack of nitrogen is seen in the corn plant if the older leaves start turning yellow at the tips. And gradually the entire leaf turns yellow in a V-shape until it wilts and falls off.
You will need to identify which nutrient your corn plant is deficient in. You can do this by a visual examination of the corn to determine the pattern and scope of the coloration (and discoloration) on the corn. Plus, you can perform a soil test to test and confirm any deficiencies in the soil.
Once you know the nutrient lacking in the soil, you can add it as a supplement. Lack of nitrogen or potassium can be covered by using a fertilizer that is rich in these nutrients. We can resolve the lack of sulfur by adding elemental sulfur to the soil.
My advice is to prevent your soil from reaching a condition where it lacks nutrients. This is easier to do than you think.
Just add some compost or organic fertilizer to the soil every month when the corn plants are in the growing season. These materials will give a boost of nutrients and beneficial organisms to the soil.
Before you grow the corn plants, you can get a soil test for your garden. This will show you if there are any nutrient deficiencies and what you need to do to resolve them. You can get this test done for a reasonable cost from your local extension service.
To prevent corn plants from turning yellow, it is important to provide them with the right environment and care. This includes providing adequate water, nutrients, and sunlight. It is also important to check for signs of pests and diseases and to treat them promptly if they are detected. Furthermore, it is important to avoid over-fertilizing and over-watering, as this can cause nutrient deficiencies or rot. If corn plants have already started to turn yellow, the issue can be addressed by identifying the root cause and taking steps to resolve it. – Tom Monson, Owner of Monson Lawn & Landscaping
You know lack of nutrients can cause yellowing in the corn plants. And you feel adding more nutrients is better for the plant. But excess nutrients cause their own problems that can lead to yellowing as well.
Over-fertilization is easier to do if you use synthetic fertilizer than organic fertilizer. This is because they are in concentrated form and available to the soil as soon as you add it.
Too much fertilizer leads to the problem of fertilizer burn where the corn plant’s roots literally get burned. This means that the roots cannot absorb the required nutrients and moisture from the soil. This will show up in the corn plant with the symptom of yellowing leaves and stem.
You can dig into the soil and check the condition of the roots. If you see the root burn, you know it’s because of excess fertilizer.
The solution is to immediately stop adding any more fertilizer to the soil. You need to flush out the excess fertilizer as well. Give the soil plenty of watering so the fertilizer can leach out from the soil.
If there are still healthy roots left, you need to give the plant sufficient time to recover. If most of the roots are damaged, the plant will continue dying and you won’t be able to recover it.
My advice is to use organic fertilizer and compost rather than synthetic ones. This gives you fewer chances of over-fertilizing and damaging the corn plants.
Regardless of which type of fertilizer you use, I suggest following the instructions provided by the manufacturer on the fertilizer packet. Only use the recommended amount and at the appropriate intervals, as mentioned.
You only need to use the fertilizer once the corn seedlings have started to mature. Avoid using fertilizer when the seeds are planted and the seedlings are sprouting.
Nutrient deficiencies are one reason why your corn plant might be turning yellow. Corn requires a balance of essential nutrients, including nitrogen, phosphorus, and potassium. If the soil is deficient in any of these nutrients, the leaves of the plan will turn yellow. To prevent this, ensure that the soil is well-fertilized with a balanced fertilizer before planting. – Jeremy Yamaguchi, CEO, Lawn Love
5. Cold weather
Corn is a warm-season plant that needs temperatures between 85 to 90 F to grow well. If the temperature drops below the required for several days, the corn plant leaves will turn yellow.
This happens because the cold temperatures cause stress on the plant and it’s unable to absorb the required nutrients from the soil.
If the temperature drop is only for a few days, the corn plant will recover and get back to growing green and healthy. But if it’s for many days, the leaves will turn yellow, wilt, and fall off.
If you find the temperatures are going to drop, you can protect the corn plant with a row cover at least during the night. It will help keep the plant warm and survive the short-term cold weather.
If you’re growing the corn in a container, you can move it indoors to the garage or basement where the temperature would be warmer than outdoors.
These solutions will only help when the temperature drop is for a short period of a few days. Otherwise, there’s nothing you can do and prevention of such an issue is something you need to work towards for the next time.
Corn is a warm-season plant, so start growing it only when the temperatures are between 80 to 90 F. So the ideal time is to grow the plants in the peak of summer in most places.
You want to avoid growing the corn plants in early spring or late fall when there is a high chance of cold weather affecting the plants for several days.
If you are in a region that has a short growing season during summer, you may need to consider using a greenhouse to grow the corn plants to keep them warm.
6. Hot weather
You know corn is a warm-season plant, which means it loves growing in warm weather between 85 to 90 F. But too much heat can actually cause the leaves to turn yellow.
This can be because the corn plant is getting stressed from the high temperatures and it’s also lacking the required moisture to absorb nutrients from the soil.
The hot weather will start curling the leaves as they try to protect themselves and keep as much moisture as possible.
If the high temperatures are temporary and only for a couple of days, the corn plants will recover well. The leaves will revert to their healthy, green state once the temperatures return to normal.
If the high temperatures continue for several days, the leaves will continue turning yellow to brown and fall off as they die.
You can try using a row cover that may add some shade to the corn plants and protect them from the high temperature. But this is a temporary measure you use during the scorching afternoons.
If you’re growing the corn plants in containers, you can move them indoors during the scorching afternoons. You can move them to a garage, basement, or a location in the garden where there is sufficient shade.
If possible, you want to avoid your corn plants from too much heat. You can check the average temperatures of your region and grow the plants when the weather is optimal for them.
If the weather gets too hot during the growing season, you can consider using row covers, fabric, or plastic sheets to protect the corn plants from the intense heat, especially during the afternoon.
Pests are another problem that can infest the corn plants and cause the leaves to turn yellow. There are several pests that may attack your corn plants, including aphids, thrips, spider mites, Japanese beetles, cutworms, Corn flea beetle, armyworms, etc.
Some of these insects such as aphids and thrips suck the sap out of the leaves, causing deficiencies and turning them yellow. Other insects would chew on leaves and stems, causing nutrient deficiencies in the plant.
If the corn plants are infested with pests, you first need to understand the type of pest it is. The solution will depend on knowing the pest.
If the corn plant is infested with aphids, you can use a spray of water to knock them down into the soil. You could also use soap and water solution to get rid of them.
You can’t use the same solution for all types of insect pests. Recognize the pest and then use the Internet to find out the solution.
I would not recommend using chemical pesticides on the corn plants as it can cause problems for the plant and the environment. Prefer using organic pesticides and in the right dose and schedule, as mentioned by the manufacturer.
Your corn plants will get infested by some pest at some point of time. That is just the way nature works. But you can do your best to keep the corn plants healthy so they can fight off large infestations.
Make sure the corn plants are getting the required nutrients, moisture, and sunlight, so they are growing well. You can try growing some herbs and insect-repelling plants around the corn plants.
I suggest adding neem fertilizer to the soil to protect the corn plants from soil pests. You may spray diluted neem oil every few weeks on the corn plants just as a preventive measure.
Like pests, diseases are another problem that your corn plants may face. And often, one of the symptoms starts with yellowing of the leaves and stems.
There are several different diseases that can affect a corn plant, including fungal, bacterial, and viral infections. Some diseases include Bacterial Leaf Streak, Bacterial Stalk Rot, Common Rust, Fusarium Stalk Rot, Fusarium Root Rot.
I recommend monitoring your corn plants every morning as part of your daily routine. It’s a lot easier to take care of disease problems as soon as they appear on the plant.
The first step is to identify the disease by using the signs and symptoms you see on the corn plant. You can use an online search to figure out the cause of the problem. Once you know the disease, you can find the solutions for that problem.
If it’s a fungal or bacterial disease at the initial stages, you may prevent further infection by cutting off the infected parts of the corn plant. Dispose of these parts by burning them away from the other plants.
If the corn plant is affected by a viral disease, there’s nothing you can do about it. The plant will gradually get affected in all the parts and die at some point. But these plant diseases don’t affect humans, so you can continue to enjoy the corn as it grows and develops cobs.
I recommend growing corn plant varieties that have been treated to prevent some of the viral and bacterial infections.
It’s easier to prevent fungal problems in the corn plants by avoiding humid conditions around the plant. Water the soil near the base of the plant and prevent water from splashing on the foliage. Water the plants early in the morning so the excess moisture can evaporate once the sun comes up.
Keep sufficient space between the corn plants so they don’t crowd each other and cause a humid environment to build up. If you find the corn plants crowding each other, you can try pruning some leaves and plants.
You can consider spraying diluted neem oil solution every few weeks on the corn plants as a preventive measure for fungal diseases.
If you’ve been growing the corn plants for a long time, they will get old and one symptom will be yellowing leaves at the bottom.
This is completely normal and part of the plant’s lifecycle. There’s nothing you can do about this. But you can remove the old leaves so the plant can focus its energy on the younger ones. You can add the old leaves to your compost pile.
Here are some of my favorite container gardening tools
Thank you for reading this post. I hope it helps you with your gardening needs. I’ve listed some tools below that can help you with container gardening. These are affiliate links so I’ll earn a commission if you use them.
Gardening Gloves – I find the Pine Tree Tools Bamboo Gardening Gloves really good for both men and women. It’s made from bamboo so helps absorb perspiration. They are also comfortable and fit very well.
Containers – You know picking the right container is crucial for your container gardening. I’ve written a detailed post on the best containers you can choose from. If you’re happy with a plastic container, you can check out the Bloem Saturn Planter.
Watering Can – This is a must-have tool when you’re growing plants in pots or grow bags. It helps to water the potting soil without splashing on the foliage. The Kensington Watering Can is stylish, strong, and can provide precision when watering potted plants.
Trowel – Garden Guru Trowel is my favorite because it’s durable and comfortable to use. My gardening friends really love having a trowel because they use it for digging soil, mixing fertilizer, moving seeds, leveling out the soil, mixing compost or mulch, and also dividing tubers
Bypass Pruner – I really like the Corona Bypass Pruner because it’s durable and gives a clean cut that helps plants recover faster. If you’re looking for something cheap, get the Fiskars Bypass Pruner that is really good as well.
To see an extensive list of the best container gardening tools gardeners recommend, check out this resource that I made for you.
Kevin is the founder of Gardening Mentor, a website that aims to teach people to grow their own food in a limited space. As a self-taught gardener, Kevin has spent several years growing plants and creating gardening content on the website. He is certified in Home Horticulture and Organic Gardening by expert gardeners from Oregon State University.