Cabbage in Zone 8B — Pacific Northwest

Cabbage thrives in our Pacific Northwest gardens, offering a satisfying crunch and mild flavor that store-bought varieties just can’t match. Its versatility shines in slaws, stir-fries, and even simple roasted wedges – a welcome fresh taste from your own backyard. Plus, those cool nights we get here seem to sweeten the flavor!

While we might struggle with heat-loving plants, Cabbage is right at home in our climate. Our long, mild fall extends the harvest, and we can avoid the worst of late blight with careful timing. You have about a 210-day growing season to work with, giving you ample time to nurture your cabbages.

To get a head start on your spring cabbage crop, start seeds indoors from early to late February, roughly six weeks before you plan to transplant them outdoors. Use seed trays or small pots filled with a good seed-starting mix. Keep them in a warm spot, ideally around 70°F, and provide plenty of light – a grow light really helps during those overcast spring days.

Bottom watering is key when starting seeds indoors. Set your seed trays in a shallow tray of water and allow the soil to absorb the moisture from the bottom. This encourages strong root growth without disturbing the delicate seedlings. Our springs can be slow to warm, so the extra time indoors gives your cabbages a competitive edge.

Transplant your cabbage seedlings outdoors from late March through mid April, once the soil has warmed up a bit. Before planting, harden them off 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.

Space your cabbage plants 12-18 inches apart in rows. Our wet springs can sometimes lead to fungal issues, so good air circulation is important. Keep an eye on the weather forecast; a late frost can still occur, so be prepared to cover your young plants if needed.

Cabbage needs consistent moisture to thrive, but overwatering is a problem in our often-damp climate. Aim for about 1 inch of water per week, either from rainfall or irrigation. During our dry summer months, you'll likely need to supplement with watering.

The "finger test" is a great way to check soil moisture. Stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water. Water at the base of the plants rather than overhead. This helps to prevent fungal diseases in our humid environment.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch, like straw or shredded leaves, can help retain moisture and suppress weeds.

You can expect your first cabbage harvest from late May through mid July, about 70 days after transplanting. The best way to tell if a cabbage is ready to harvest is to give the head a gentle squeeze. If it feels firm and solid, it's ready. Also, make sure it's reached the full size typical for its variety.

To harvest, use a sharp knife to cut the cabbage head at the base of the plant. Leaving the outer leaves intact can sometimes encourage the plant to produce smaller side shoots, offering a second, smaller harvest.

As our first frost approaches in early November, harvest any remaining cabbages, even if they aren't quite as large as you'd hoped. They'll store well in a cool, dry place for several weeks.

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

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 loopers move in a distinctive looping motion. They also chew holes in leaves.
• What causes it: Larvae of a moth.
• How to fix/prevent it: Bt spray is effective. Handpick. Encourage beneficial insects like parasitic wasps and lacewings.

Splitting

• What it looks like: The cabbage head cracks open.
• What causes it: Inconsistent watering. A period of drought followed by heavy watering can cause the head to swell too quickly and split.
• How to fix/prevent it: Maintain consistent soil moisture. Mulch to help retain water. Harvest promptly when heads are mature.

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.

Pacific Northwest Specific Challenges: Our mild summers and dry summer months help to minimize some pest and disease pressures on cabbage. However, our wet springs can create favorable conditions for clubroot. Also, slugs can be a nuisance, especially for young plants. Use slug bait or traps to protect your cabbages.

Companion planting can give your cabbage a boost in the Pacific Northwest. Green beans fix nitrogen in the soil, benefiting cabbage's growth. Celery repels cabbage white butterflies, reducing the risk of cabbage worm infestations. Onions and dill deter many pests, while potatoes can improve soil structure.

Avoid planting cabbage near tomatoes, strawberries, or peppers. Tomatoes and peppers compete for nutrients and can attract pests that also affect cabbage. Strawberries can harbor diseases that may spread to cabbage.