Cabbage is an essential food crop grown in several states across the US. While it is easy to grow in your garden, you might be distressed to find your crop’s leaves turning yellow.
Cabbage leaves turn yellow for several reasons, such as overwatering, poor-quality soil, and disease. Careful observation of your plants may reveal the cause, allowing you to tackle the problem.
Unfortunately, at the stage of yellowing leaves, your cabbages may be beyond saving. Harvest what you can, and read on to learn more about this phenomenon and how you can prevent it from happening in the future.
Also Read: How To Get Seed From Cabbage Plant
Unsuitable growing conditions can contribute to yellowing cabbage leaves. Let’s take a look at some of these below.
Consider your watering habits. If you are a novice gardener, you may be surprised that less is often more when it comes to water. Leafy greens like cabbage require a fair amount of water but will become problematic if they get too much of it.
Overwatering can wash away nutrients in the soil. Poor-quality soil can result in yellowing leaves, and continuing to work in poor soil is an exercise in futility.
Reducing your watering frequency may yield better results if your soil quality has not been affected. If excess rain is causing your plants to get too much water, consider planting them at a different time of the year so they’ll experience less wet weather.
If your soil is draining poorly, build a raised bed. A depth of 23” (60cm) is recommended in combination with well-draining, loamy soils. Check out this video for some advice on planting cabbages in raised beds.
If you cannot build a raised bed, mixing wood chips into your soil can help improve drainage and the soil’s overall health. Do not use fresh or home-chipped mulch.
Wood chips must be partially decomposed before use in your cabbage patch. You can buy commercially available wood chips for use in your garden or bag up your own chips and store them for a year before use.
Cabbages prefer nitrogen-rich soils that are not too acidic. If your soil does not contain the proper nutrients in the first place, it will be impossible for healthy plants to grow. As a result, you may notice yellowing cabbage leaves.
You can get a Luster Leaf Rapitest Test Kit from Amazon to test your soil and determine acidity, nitrogen, potassium, and phosphorous levels. This kit accommodates a total of 40 tests and straightforward enough for use by both beginners and the most experienced gardeners.
Cabbages like to grow in soil with a pH of around 6.5. You can amend your soil to accommodate your cabbage plants better. Your soil test kit should tell you whether you need to add nutrients.
Add lime to your soil if it is too acidic. On the other hand, using pine needle mulch will add acidity. Only add phosphorus and potassium according to your test kit’s recommendations.
Check out: How Do I Know if My Cabbage Plant Is Dying?
On the flip side of overwatering, your cabbages will suffer if they do not get enough of Earth’s most precious resource.
A thirsty cabbage will wilt, eventually discoloring as it begins to dry out. The leaves will eventually turn brown and die.
The first thing you need to remember is that cabbages love cooler weather. If you’re trying to grow cabbages in a Tampa summer, you will run into trouble.
All you can do with an underwatered cabbage is give it water as soon as possible. Plan to grow in the cooler months. Cabbages grow optimally around 55-75 °F (13-24 °C).
Cabbages are also hardy in the frost, so you can plant them perhaps earlier than you think. The seeds germinate at temperatures as low as 39.2 °F (4 °C). So, if you live around New York, you can start planting around mid-March.
Loads of pathogens can prey on cabbages, many of which will cause leaves to turn yellow. These are some of the main culprits:
- Fusarium (Yellows)
- Black Rot
Let’s take a look at each of these diseases in more detail.
This hardy soil-borne fungus is problematic mainly in warmer climates. As the name implies, the first sign of this fungus is usually discoloration and abnormal growth of the leaves.
Eventually, the vascular tissue turns brown, and your cabbages are destroyed. This fungus resembles another condition called Black Rot, which turns the veins of cabbage leaves black. It’s usually easy to tell the difference once the disease progresses.
It infects the root system of young cabbages, growing optimally at soil temperatures between 80 and 90 °F (26 and 32 °C), slowly killing them from the inside out. By the time you see signs of Yellows, it’s too late.
The best way to handle Fusarium is to avoid it altogether. Be careful when transplanting seedlings into your garden—you can easily contaminate your garden if your seedlings have been growing in Yellows-infested soil.
Growing your cabbages in cooler months when Fusarium does not grow will ensure this disease does not afflict your harvest. Cabbages are cold and frost-resistant, preferring cooler weather. Still, this solution may not be viable if you live in a warmer area, like Florida or California. Luckily, there are other ways to avoid Yellows.
Another option is to grow a Yellows-resistant cabbage variety. There are many you can choose from. Cornell University has compiled a handy list that you can refer to for ideas.
Have you noticed that your cabbages wilt during the day, only to perk up again in the evening? You may be dealing with Clubroot.
Clubroot is caused by a soil-borne mold that infects the root system, causing abnormal growth and poor function.
Pull a head of cabbage if you suspect Clubroot. If the fungus is present, you will see masses of nodules all over the root system.
Sadly, the pathogen that causes Clubroot is a hardy one. It does seem to favor more acidic soils, though. Crucifers in soil with a pH of 6.5 or less are more likely to be afflicted by Clubroot.
Use a soil tester to confirm the acidity of your soil and adjust accordingly. Amending the soil with lime will bring the acidity down prior to planting.
It’s also recommended that you wait at least six years before planting cabbages in the same patch. Luckily, the ground should at least be viable for other crops in the meantime.
It’s as bad as it sounds. By the time you notice the symptoms of black rot.
This bacteria destroys the vascular system of your cabbages. Young plants will develop smaller heads, and you’ll notice the trademark V-shaped calling card on the leaves.
The scourge of black rot is easier to avoid than cure. You can take steps to discourage the spread of the disease to your garden.
Vigilant weeding will ensure that wild crucifers do not spread the disease to your plants. Carefully bag and dispose of any damaged plants.
There are many precautions and steps to take when dealing with a black rot infection, focusing on damage control. Refer to this guide for more information.
Have a look: Homemade Bug Spray for Cabbage Plants
Many creatures enjoy cabbages eating just as much as we do. Aspiring farmers must be vigilant if they do not wish to share their hard work with nature.
Attacks from hungry mice, rabbits, deer, and other relatively large wildlife will be far less subtle than yellowing leaves. Still, they can inadvertently spread harmful bacteria that will cause such symptoms.
Fixing a pest problem depends on which pests are present. Most people seem to get away with having an open cabbage patch, but you may need to take extra precautions to keep critters away from your leafy greens.
If you notice a tiny green cabbage caterpillar on your plant, pick him off and scrutinize your crops for more. These caterpillars turn into white butterflies, which might be pretty but leave ugly holes in your crops.
An old folk remedy for caterpillars is to sprinkle rye flour over caterpillars. This is supposed to dry them out. You can also plant thyme near your cabbages, as it is a natural caterpillar deterrent.
Installing row covers will prevent adult butterflies from laying eggs on your plants. I recommend these CJGQ Plant Covers from Amazon. They come with breathable blankets and hoops to keep the covers off your plants. Not only do they protect against insects, but they also can be used to shelter your plants from frost and harsh sunlight.
Read: Holes in Cabbage Plant Leaves? [What needs to do]
Building a fence around your cabbage patch will keep some of the larger critters at bay. If you have a rabbit problem, you may have to bury the fence to prevent them from burrowing underneath.
For other pests like rats and mice, a fence won’t work. Try something like this Kensizer Humane Rat Trap off Amazon. This way, you won’t be killing innocent creatures opportunistically feeding from your garden.
It’s possible to grow your cabbages without sharing them with neighboring critters. If your plants are fenced in and covered, they should be safe from most pests.
Furthermore, have a look at the below more gardening articles:
- Why Is My Cabbage Plant Giving Tall Sprouts?
- Cabbage Leaves Turning Brown? [Causes & Cares]
- Should I Cut Off Brown Hydrangea Blooms?
- Hydrangea Turning Brown? [Reasons & Cares]
- Lawn Fungus: What Causes it and How to Deal with it?
Now that you are armed with some knowledge about the conditions that lead to yellowing cabbage leaves, you can determine which of them is the most likely culprit and begin remedying the situation.
It may seem challenging to determine the exact cause of your discolored crucifers. Still, the most likely reasons are easy enough to discern, since they affect the plant differently.
I’m Elsa, and I love gardening. I started GardeningElsa.com as a resource for other gardeners, and I offer expert advice on gardening topics such as plants, flowers, herbs, and vegetable gardening. On my website, I share my latest tips and tricks for creating beautiful gardens. When I’m not working on my website, you can find me in my own garden, tending to my plants and flowers. Read more about me.