My plants turning yellow on leaves
3
@WorthyBoneset Hello 👋 and welcome to Greg, Wise.
Could you provide us with a picture or two so we can properly identify the problem?
There are many possible reasons why cabbage leaves may be turning yellow, including overwatering, underwatering, environmental stress, lack of sunlight, too hot temperatures, nutrient deficiencies, clubroot, cabbage black rot, and bottom rot.
Cabbages are more sensitive to overwatering than underwatering. When cabbages are excessively watered, the leaves can become yellow and wilted due to lack of oxygen reaching the roots. This prevents the plants receiving vital nutrients and can cause the leaves to yellow. It can also create the perfect storm for diseases like clubroot and black rot to set in. When you’re growing cabbage, keep the soil lightly moist, not constantly wet and soggy. Water during dry spells, but not excessively.
If you consistently overwater your cabbage plants, you’ll see yellowing leaves toward the bottom and, as the plant matures, if it survives long enough to form a head, the head will split open down the center, as the cells overhydrate and burst.
Underwatering
Underwatering causes the cabbage leaves to turn yellow due to lack of water and nutrient uptake from the soil. This will also cause them to become wilted, as not enough water is being absorbed by the plant. Cabbage family plants are pretty fussy when it comes to water. They dislike over and underwatering. And unfortunately, the symptoms are essentially the same, at least at first. So check the soil around an inch below the ground to see if it’s wet or dry.
I just stick my finger in and see if it comes away wet or dry, but if you want a more scientific approach, you can use a moisture sensor like this one.
Environmental Stress
Cabbage plants are sensitive to environmental stresses such as high wind and extreme temperatures. These types of stress can cause the leaves to yellow and become wilted. And there’s only so much you can do about these things. The key is good planning.
And I try to make sure they aren’t in constant direct sunlight. Instead, I companion plant with taller plants that can provide a little dappled shade, or I plant my cabbage crop in a sheltered but sunny area of my growing space, depending on what my crop rotation needs are for that particular year.
Lack of Sunlight
Cabbages need 6 to 8 hours of direct sunlight each day in order for them to grow healthy and strong. Without enough sunlight, the leaves can turn yellow due to lack of photosynthesis and nutrient absorption. But, interestingly, your cabbage plants will also need some shade to protect them from extreme heat.
Too Hot
Cabbages prefer temperatures in the range of 50 to 75°F (10 to 24°C). When temperatures get too high for too long, it can cause the leaves to yellow and become wilted. If you regularly experience very high temperatures and still want to cultivate cabbage, make sure you provide some shade.
Nitrogen Deficiency
A nitrogen deficiency is the most common nutrient problem in cabbages that causes yellowing leaves. If your cabbage plants are lacking nitrogen, you’ll see the leaves turning yellow from the bottom, up.
Nitrogen is taken up by the roots and moves very slowly throughout the plant. And it’s mobile, so the plant can move the nitrogen where it needs it. So, if there isn’t enough nitrogen in the soil, the growing cabbage moves what nitrogen it does have towards the top, where it’s trying to produce new leaves or nurture the maturing head. And so, the leaves start to turn yellow from the bottom up, as the lower leaves are deprived on nitrogen first.
You can’t turn the yellow leaves green again, but you can provide more nitrogen to save the rest of the plant. And, if you want to be certain that it’s nitrogen deficiency, you can get a simple soil test like this one to check the basic soil nutrient profile. Then add a nitrogen-rich fertilizer, like blood meal or chicken manure pellets.
Club Root
Club root (Plasmodiophora brassicae) is a fungal disease that can cause yellowing in cabbage leaves and other cruciferous plants. Young plants succumb quickly and often die off, but mature plants may survive although will be stunted and may not form a head.
Once this disease takes hold, there’s not much you can do about it. You’ll see that leaves turn a pale yellow and, during hot weather, they wilt. But the leaves recover at night, only to wilt again the following day. This is a telltale sign of club root.
It’s a common issue in wet soils, particularly if the soil also has a low pH. The cabbage plant roots become swollen and stunted, with large, spindle-shaped galls that inhibit water and nutrient uptake.
Could you provide us with a picture or two so we can properly identify the problem?
There are many possible reasons why cabbage leaves may be turning yellow, including overwatering, underwatering, environmental stress, lack of sunlight, too hot temperatures, nutrient deficiencies, clubroot, cabbage black rot, and bottom rot.
Cabbages are more sensitive to overwatering than underwatering. When cabbages are excessively watered, the leaves can become yellow and wilted due to lack of oxygen reaching the roots. This prevents the plants receiving vital nutrients and can cause the leaves to yellow. It can also create the perfect storm for diseases like clubroot and black rot to set in. When you’re growing cabbage, keep the soil lightly moist, not constantly wet and soggy. Water during dry spells, but not excessively.
If you consistently overwater your cabbage plants, you’ll see yellowing leaves toward the bottom and, as the plant matures, if it survives long enough to form a head, the head will split open down the center, as the cells overhydrate and burst.
Underwatering
Underwatering causes the cabbage leaves to turn yellow due to lack of water and nutrient uptake from the soil. This will also cause them to become wilted, as not enough water is being absorbed by the plant. Cabbage family plants are pretty fussy when it comes to water. They dislike over and underwatering. And unfortunately, the symptoms are essentially the same, at least at first. So check the soil around an inch below the ground to see if it’s wet or dry.
I just stick my finger in and see if it comes away wet or dry, but if you want a more scientific approach, you can use a moisture sensor like this one.
Environmental Stress
Cabbage plants are sensitive to environmental stresses such as high wind and extreme temperatures. These types of stress can cause the leaves to yellow and become wilted. And there’s only so much you can do about these things. The key is good planning.
And I try to make sure they aren’t in constant direct sunlight. Instead, I companion plant with taller plants that can provide a little dappled shade, or I plant my cabbage crop in a sheltered but sunny area of my growing space, depending on what my crop rotation needs are for that particular year.
Lack of Sunlight
Cabbages need 6 to 8 hours of direct sunlight each day in order for them to grow healthy and strong. Without enough sunlight, the leaves can turn yellow due to lack of photosynthesis and nutrient absorption. But, interestingly, your cabbage plants will also need some shade to protect them from extreme heat.
Too Hot
Cabbages prefer temperatures in the range of 50 to 75°F (10 to 24°C). When temperatures get too high for too long, it can cause the leaves to yellow and become wilted. If you regularly experience very high temperatures and still want to cultivate cabbage, make sure you provide some shade.
Nitrogen Deficiency
A nitrogen deficiency is the most common nutrient problem in cabbages that causes yellowing leaves. If your cabbage plants are lacking nitrogen, you’ll see the leaves turning yellow from the bottom, up.
Nitrogen is taken up by the roots and moves very slowly throughout the plant. And it’s mobile, so the plant can move the nitrogen where it needs it. So, if there isn’t enough nitrogen in the soil, the growing cabbage moves what nitrogen it does have towards the top, where it’s trying to produce new leaves or nurture the maturing head. And so, the leaves start to turn yellow from the bottom up, as the lower leaves are deprived on nitrogen first.
You can’t turn the yellow leaves green again, but you can provide more nitrogen to save the rest of the plant. And, if you want to be certain that it’s nitrogen deficiency, you can get a simple soil test like this one to check the basic soil nutrient profile. Then add a nitrogen-rich fertilizer, like blood meal or chicken manure pellets.
Club Root
Club root (Plasmodiophora brassicae) is a fungal disease that can cause yellowing in cabbage leaves and other cruciferous plants. Young plants succumb quickly and often die off, but mature plants may survive although will be stunted and may not form a head.
Once this disease takes hold, there’s not much you can do about it. You’ll see that leaves turn a pale yellow and, during hot weather, they wilt. But the leaves recover at night, only to wilt again the following day. This is a telltale sign of club root.
It’s a common issue in wet soils, particularly if the soil also has a low pH. The cabbage plant roots become swollen and stunted, with large, spindle-shaped galls that inhibit water and nutrient uptake.
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