Help! Why Is My Cabbage Not Forming Heads?

Cabbage is fairly easy to grow, but sometimes things might not go as expected. I have grown this veggie for years, and there are times when heads don’t form. This condition can be caused by several factors, including high temperatures, excessive nitrogen, and inconsistent watering, among others.

Before I delve into details, it’s important to know that cabbage is a cool-season crop that’s best suited for spring or fall planting. The vegetable also prefers sunny locations and fertile, well-drained soil. Watering must be deep and consistent without overwatering.

In the right conditions, your cabbage should form heads in as little as 60 days. However, some varieties, such as Danish Ballhead take slightly longer. If you want to know the exact time when heads form, check what the company indicates on the packet of your cabbage seed.

Why Your Cabbage Won’t Form Heads

As I mentioned, a glitch in climatic conditions or gardening approach may result in cabbage not forming heads. As a seasonal grower, I have encountered this problem several times until I figured out the real causes and how to fix them.

1. High temperature

Cabbage are cool season crops which thrive when temperatures are cooler. This means growing in spring or fall gives the best results. Temperatures above 80°F may result in either cabbage not forming heads or they’ll bolt (produce flowers and then go to seed).

It is also important to know that extremely cold temperatures aren’t good for cabbage. Below 30°F, the plant can be damaged or killed. So, when growing cabbage, ensure you have about 60 days in the ideal temperature range. In milder climates, you can still harvest your cabbage during winter.

2. Too much nitrogen

Nitrogen is important when growing plants for their leaves. The nutrient is a major component of chlorophyll, the compound that absorbs light energy useful in the production of sugars. However, too much nitrogen can cause cabbage to focus excessively on foliage rather than forming heads.

To prevent this problem, avoid fertilization during head formation. You can push more on phosphorus a few weeks after planting so that the plants’ focus is more on root development. Phosphorus-rich fertilizer or one meal has always offered me great results, particularly in spring.

3. Inconsistent watering

Cabbage needs about 1-2 inches of water per week. In fact, over 90% of a cabbage is water. So, without proper watering, your cabbage will not form heads. To prevent this issue, make sure you are watering constantly but without overwatering. Too much water in the soil can cause root rot.

4. and diseases

Pests such as cabbage worms, aphids, and flea beetles can stop the vegetable from forming heads. When they chew holes in the leaves, it results in damage that can prevent the plant from growing as required. So, it’s important to inspect and control pests with appropriate insecticides.

Tips for growing cabbage in your garden

Growing cabbage isn’t as complex as long as you are doing it at the right time of the year. You can start from seed or transplants. There are wide varieties you can choose from, including the Danish Ball Head, Ruby Ball, Golden Acre, and Savoy Ace, among others.

To determine a variety that does well in your area, you can visit the nearby gardening center for enquiries. Once you have decided on the type of cabbage to plant, here are a few tips for growing this vegetable in your garden.

1. Time your planting

Spring and fall are the best times to grow cabbage. If you prefer spring, transplants should be planted 2-3 weeks before the anticipated last day of frost in the growing area. For fall planting, choose early maturing cultivators and plant 50-75 days before the anticipated maturity date. 

2. Soil preparation

Before planting, conduct a soil test to determine its nutrient level. If the test report recommends adding fertilizer, work it into the soil a week before planting. You can also fertilize with a well-decomposed compost, but apply no more than 1 inch of the organic matter per 100 square feet.

3. Planting and spacing

Spacing is important when seeding or planting cabbage. Plants should sit 8-12 inches from each other in rows that are 2-3 feet apart. This not only provides enough space for head formation but also allows light and proper air flow to the plants.

4. Watering

To encourage growth, water your cabbage deeply and infrequently. Provide about 1-2 inches of water per week. Inconsistent watering can cause heads to split or fail to form altogether. You may apply mulch around the plants to help conserve soil moisture and reduce weed growth.

5. Fertilizing

Cabbage needs fertile soil to thrive. A nitrogen-based fertilizer, 4 weeks after planting, will encourage growth. As the heads begin to form, cut down on nitrogen and push more on phosphorus. High nitrogen levels is one of the reasons cabbage won’t form heads.

6. Pests and disease control

Cabbage plants can be prone to pests and diseases. Leaves curling, spots on heads, and poor growth are some of the signs to watch out for. The best approach is to conduct regular inspections and take appropriate measures to control any issues.

For the problem of pests, treat with an appropriate insecticide or use a strong stream of water to dislodge the insects. Practicing good sanitation and avoiding overhead irrigation can help prevent most diseases on your cabbages, but an appropriate fungicide can be useful in treatment. 

How to harvest and store your cabbage

Regardless of the size, cabbage heads are ready for harvest when they are fully mature. In particular, there is no change in color, but you can tell by looking at what the seed company indicates on the packet. The estimates are pretty accurate within 10 days or so.

A mature cabbage head will also feel firm in your palm when you try to squeeze. However, some varieties, such as Napa cabbage, might not form that nice compact head you are expecting, but you will still get some delicious leaves to use in your kitchen.

Delay in harvesting can result in the cabbage head splitting open and flowering. This is common when temperatures start rising above 80 degrees F. To avoid losses, cut your cabbage heads early enough and store them. They can last 2-3 months in your refrigerator when wrapped in a plastic bag.

Final thought

Cabbage is a nutritious vegetable, and you can easily grow it in your garden to enjoy freshness anda steady supply. One of the common challenges is cabbage not forming heads. From my gardening knowledge, it is often a problem of temperature, excess nitrogen, and poor watering.