Cabbage in Zone 6A — Northeast

Growing cabbage here in the Northeast is incredibly rewarding. Nothing beats the crisp, fresh taste of a homegrown cabbage, especially after a long winter. Plus, they’re so versatile in the kitchen, from slaws to stir-fries to hearty soups that are perfect for those cool fall evenings.

Our short growing season and the occasional late frost can be a challenge, but with a little planning, you can absolutely grow beautiful cabbages. Our 178-day growing season is just enough time to get a great spring crop if you start your seeds indoors.

To get a head start on our short growing season, start your cabbage seeds indoors from mid-February through early March. This gives you about 6 weeks to get them strong before transplanting. Use seed trays with a good seed-starting mix and provide consistent warmth and bright light – a simple grow light works wonders.

Water your seedlings from the bottom to avoid damping off. Set the tray in a shallow dish of water and let the soil soak it up from the bottom for about 10 minutes. This encourages strong root growth, which is essential for coping with our late springs that often bring unexpected cold snaps.

Remember, the goal is to get those seedlings ready to thrive as soon as the weather cooperates, so don't jump the gun and set them out too early.

Transplant your cabbage seedlings outdoors in early April through early May, after the danger of hard frost has passed. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Start with an hour or two of shade and increase the time each day.

When transplanting, space your cabbage plants 12-18 inches apart. Our spring weather can be unpredictable, so keep an eye on the forecast and be prepared to cover your plants if a late frost threatens.

Cabbage needs consistent moisture to thrive, but overwatering can be just as harmful as underwatering, especially with our moderate-to-humid summers. The goal is to keep the soil evenly moist, not soggy. Aim for about 1 inch of water per week, either from rainfall or irrigation.

The finger test is your best friend: stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water. During hotter periods, you might need to water more frequently. Water at the base of the plant to avoid wetting the leaves, which can encourage fungal diseases in our humid climate.

Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A good layer of mulch, like straw or shredded leaves, will help retain moisture and keep the soil cool, which is especially important as we move into summer.

You can expect your first cabbage harvest from mid-June through early August, about 70 days after planting. The key is to check for firmness. When the head feels solid and firm when you squeeze it, and it's reached a good size for the variety you're growing, it's ready to harvest.

Cut the cabbage head at the base with a sharp knife, leaving the outer leaves intact. These can sometimes produce smaller side shoots that you can harvest later. Unfortunately, cabbage doesn’t ripen off the vine, so you have to harvest when it’s ready.

As our first frost approaches in mid-October, harvest any remaining cabbages, even if they're not quite fully mature. They'll store better if they are mature, but immature heads are still usable.

Here are some common problems you might encounter growing cabbage in the Northeast:

Cabbage Worms

• What it looks like: Smooth green caterpillars on brassica leaves. Irregular holes chewed in leaves. Dark green droppings. White butterflies hovering around plants.
• What causes it: Larvae of white cabbage butterflies. Multiple generations per season in warm climates.
• How to fix/prevent it: Bt spray is very effective. Floating row covers prevent egg laying. Handpick caterpillars. Interplant with aromatic herbs (thyme, sage). Encourage parasitic wasps.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, but these caterpillars move in a looping motion. They also chew holes in leaves.
• What causes it: These are the larvae of a grayish-brown moth.
• How to fix/prevent it: Use floating row covers to prevent moths from laying eggs. Bt spray is also effective. Handpick loopers as you see them.

Splitting

• What it looks like: The cabbage head cracks open.
• What causes it: Inconsistent watering, especially heavy watering after a dry spell. Rapid growth can also contribute.
• How to fix/prevent it: Maintain consistent soil moisture. Mulch to help retain moisture. Harvest cabbages as soon as they're mature to prevent them from splitting.

Clubroot

• What it looks like: Stunted growth, wilting in afternoon heat, yellowing leaves. Roots are swollen, distorted, and club-shaped when dug up.
• What causes it: Soil-borne pathogen (Plasmodiophora brassicae) that persists in soil for 10+ years. Favors acidic, wet soil.
• How to fix/prevent it: Raise soil pH to 7.0-7.2 with lime. Improve drainage. Rotate brassicas on a 7-year cycle. Remove and destroy infected plants (don't compost). Start transplants in sterile mix.

Northeast Specific Challenges: Our moderate heat and moderate-to-humid humidity can create favorable conditions for pests and diseases. Even rainfall can also contribute to splitting if the soil dries out and then gets a sudden downpour. Consistent monitoring and preventative measures are key.

Companion planting can really help your cabbages thrive here in the Northeast. Green beans are great companions because they fix nitrogen in the soil, which cabbages love. Celery is also a good choice; its strong scent can help deter cabbage moths. Onions have a similar effect, plus they help repel aphids. Potatoes and dill also make good companions, as they can deter certain pests.

Avoid planting tomatoes, strawberries, and peppers near your cabbages. Tomatoes and strawberries can attract pests that also bother cabbages, and peppers compete for the same nutrients in our often rocky New England soil.