Cabbage in Zone 6B — Pacific Northwest

Cabbage is a rewarding crop for Pacific Northwest gardeners. Its crisp texture and slightly sweet flavor are delicious raw in slaws or cooked in stir-fries. Plus, the satisfaction of harvesting a tightly packed head you grew yourself is hard to beat. Cabbage thrives in our mild summers and cool nights, developing excellent flavor that you just can't get from store-bought varieties.

While we have a relatively short growing season of around 162 days, especially with our overcast spring days, you can absolutely grow beautiful cabbages here. Starting seeds indoors gives you a head start, allowing you to harvest before the first frosts arrive in early October. Strategic timing and a little attention make cabbage a reliable performer in our PNW gardens.

To get a jump start on your spring cabbage harvest, begin seeds indoors from late February through mid March. Starting about 6 weeks before you intend to transplant is ideal. Use seed trays or small pots filled with a good seed starting mix.

Keep the trays consistently moist, and bottom watering helps prevent damping off. Place them in a warm location or use a heat mat to encourage germination. Once seedlings emerge, provide plenty of light with a grow light, since our spring weather can be pretty grey.

Remember, our springs in the Pacific Northwest tend to be slow to warm up. This indoor start is critical to getting a good cabbage crop before the cooler weather arrives again.

Transplant your cabbage seedlings outdoors from mid April through mid May. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the cooler temperatures and stronger sunlight.

Space your seedlings 12-18 inches apart in rows. Cabbage needs room to develop those big, beautiful heads. Even though we often have wet springs, avoid transplanting into overly soggy soil.

Keep an eye on the weather forecast as you transplant. A late frost can damage young cabbage plants, so be prepared to cover them if necessary.

Cabbage needs consistent moisture to thrive, but overwatering can be just as harmful as underwatering in our climate. The key is to find the right balance, especially given our dry-summer conditions. During our wet springs, you may not need to water at all.

From late spring through the dry summer months, check the soil moisture regularly using the "finger test." Stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or irrigation. Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our sometimes humid conditions.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch around your cabbage plants can help retain moisture and suppress weeds, which is especially helpful during our dry summer months.

You can expect your first cabbage harvest from late June through mid August, about 70 days after transplanting. Don't wait too long, or the heads can split.

A ripe cabbage head will feel firm and solid when squeezed. It should also be close to the full size for the variety you're growing. To harvest, use a sharp knife to cut the head at the base of the plant.

As the first frost approaches in early October, harvest any remaining heads, even if they're not quite fully mature. Smaller cabbages can still be used in cooking.

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

Cabbage Worms

• What it looks like: Smooth green caterpillars munching on leaves, leaving irregular holes. You'll also notice dark green droppings and white butterflies fluttering around.
• What causes it: The larvae of those white cabbage butterflies. They can have multiple generations during our mild summers.
• How to fix/prevent it: Bt spray is very effective. Floating row covers are great to prevent the butterflies from laying eggs. Handpick caterpillars when you see them. Consider interplanting with aromatic herbs like thyme and sage.

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: Cabbage looper moths laying eggs on the plants.
• How to fix/prevent it: Bt spray works well on loopers, too. Handpicking is also effective. Encourage beneficial insects like parasitic wasps to keep their populations in check.

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. Water deeply but less frequently. Mulch around the plants to help retain moisture. Harvest heads as soon as they're mature.

Clubroot

• What it looks like: Stunted growth, wilting in the afternoon heat, and yellowing leaves. When you dig up the plant, the roots are swollen, distorted, and club-shaped.
• What causes it: A soil-borne pathogen (Plasmodiophora brassicae) that can live in the soil for many years. It thrives in acidic, wet soil, which we often have in the PNW.
• How to fix/prevent it: Raise the soil pH to 7.0-7.2 with lime. Improve soil drainage. Rotate brassicas on a 7-year cycle. Remove and destroy infected plants (don't compost them!). Start transplants in sterile mix.

Pacific Northwest Specific Challenges: Our mild summers and dry-summer conditions can be both a blessing and a curse for cabbage. While the cool temperatures promote excellent flavor, inconsistent watering during the dry months can lead to splitting. The overcast spring days can also slow down growth, making it even more important to start seeds indoors.

Companion planting can help your cabbage thrive. Green beans, celery, onions, and potatoes are all good companions. Beans fix nitrogen in the soil, benefiting cabbage's growth. Celery repels cabbage white butterflies, reducing cabbage worm infestations. Onions deter many pests. Potatoes don't directly benefit cabbage, but they don't compete for resources and can help break up the soil. Dill attracts beneficial insects that prey on cabbage pests.

Avoid planting cabbage near tomatoes, strawberries, or peppers. Tomatoes and peppers can stunt the growth of cabbage. Strawberries compete for nutrients and water. Proper spacing and thoughtful companion planting can go a long way in ensuring a healthy cabbage crop in your Pacific Northwest garden.