Celery in Zone 8A — Pacific Northwest

Celery, with its crisp stalks and refreshing flavor, is a rewarding crop to grow in the Pacific Northwest. Homegrown celery offers a depth of flavor you just can't find in store-bought bunches, perfect for adding a fresh crunch to salads, soups, and snacks. The cool nights and mild summers of our region actually enhance the sweetness of celery, making it a worthwhile addition to your garden.

Growing celery here does present some challenges, like the need for consistent moisture and a long growing season. But with a little planning and attention, you can absolutely enjoy a bountiful harvest. Our 203-day growing season gives you ample time to nurture these plants from seed to table.

Starting celery indoors is crucial in our climate because of our cool spring soil. You'll want to start your celery seeds indoors in late January through mid February, about 10 weeks before you plan to transplant them outside. This gives them a head start before our typically overcast spring days.

Use seed trays with a good seed-starting mix and provide consistent warmth, around 70-75°F. Celery seeds need light to germinate, so don't bury them too deeply – just barely press them into the soil surface. Bottom watering is a great way to keep the soil consistently moist without disturbing the delicate seedlings.

Remember, celery is slow to get going, so be patient. Starting them indoors early gives them the best chance to thrive once transplanted into the garden.

Transplant your celery seedlings outdoors in early April through early May, once the danger of hard frost has passed. Before transplanting, be sure to harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the cooler temperatures and stronger sunlight.

Space your celery plants 8-10 inches apart in a sunny spot that gets at least 4-6 hours of sunlight each day. Keep an eye on the weather forecast – those unexpected cold snaps can set them back.

Celery is a very thirsty vegetable, and consistent watering is key to a successful harvest in our relatively dry summer climate. Aim to keep the soil consistently moist, as even brief dry spells can lead to bitter, hollow stalks. This is especially important during the dry summer months when rainfall is scarce.

During our wet springs, you may only need to supplement rainfall with a light watering once or twice a week. However, as we move into the drier summer months, you'll likely need to water deeply several times a week, providing about 1-2 inches of water per week. Use the finger test – if the top 2 inches of soil feel dry, it's time to water.

Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases, especially if we get an unexpected humid spell. Overwatering can lead to root rot, so make sure the soil is well-draining. A layer of mulch around the plants can help retain moisture and regulate soil temperature. Signs of underwatering include wilting and stunted growth, while yellowing leaves can indicate overwatering.

You can expect your first celery harvest in early July through late August, about 85 days after transplanting. Look for outer stalks that are at least 8 inches long and thick enough to use. You can harvest individual stalks as needed, or cut the entire plant at the base when the stalks are 12 inches or longer.

To harvest individual stalks, simply use a sharp knife to cut them off at the base of the plant. For a continuous harvest, focus on the outer stalks, allowing the inner stalks to continue growing.

As our first frost approaches in late October, you can harvest any remaining celery, even if it's not fully mature. It's still usable in soups and stews, even if the stalks are a bit smaller.

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

Bolting from Temperature Stress

• What it looks like: The celery plant prematurely sends up a flower stalk, making the stalks bitter and inedible.
• What causes it: Fluctuations in temperature, especially sudden shifts from cool to warm, can trigger bolting. This is more common in our region during those temperature swings we sometimes get in spring.
• How to fix/prevent it: Choose bolt-resistant varieties. Plant after the risk of frost has passed and temperatures are more stable. Provide consistent watering and avoid stressing the plants.

Hollow Stalks

• What it looks like: The center of the celery stalks becomes hollow and airy.
• What causes it: Inconsistent watering and nutrient deficiencies. Celery needs a steady supply of moisture and nutrients to develop solid stalks.
• How to fix/prevent it: Ensure consistent watering, especially during dry spells. Fertilize regularly with a balanced fertilizer. Amend the soil with compost before planting to improve its water-holding capacity.

Stringy Stalks from Heat

• What it looks like: The celery stalks become tough and stringy, making them less palatable.
• What causes it: While we don't often get extreme heat, even our mild summer heat can sometimes cause this.
• How to fix/prevent it: Provide afternoon shade during the hottest part of the day. Consistent watering is also key to preventing stringy stalks. Choose varieties that are more heat-tolerant.

Pacific Northwest Specific Challenges: Our mild heat and dry summer rainfall mean that consistent watering is absolutely critical for celery. Late blight can also be a concern, so be sure to provide good air circulation and avoid overhead watering when possible. Slugs can also be a nuisance, so use your preferred method of slug control.

Celery benefits from companion planting. Plant it near green beans, as they fix nitrogen in the soil, benefiting celery's growth. Cabbage is another good companion, as its strong scent can deter some pests that might bother celery.

Tomatoes and onions also make good companions for celery. Tomatoes provide shade during hotter parts of the day, while onions can deter certain pests. Avoid planting celery near carrots, as they compete for the same nutrients in the soil.