Celery in Zone 6B — Pacific Northwest

Growing your own celery in the Pacific Northwest offers a unique reward. The cool nights and mild summers here actually enhance the flavor, giving you crisp, aromatic stalks that store-bought celery just can't match. Plus, there's a certain satisfaction in coaxing this somewhat finicky plant to thrive in your own backyard.

Celery can be a bit of a challenge in our region, especially with our cool springs and the potential for a shorter warm season. But don't let that deter you. With a little planning and attention to timing within our 162-day growing season, you can absolutely enjoy homegrown celery.

Start your celery seeds indoors from mid-February through early March. This gives them a solid 10 weeks to get a head start before transplanting. Celery seeds are tiny and need light to germinate, so don't bury them too deeply.

Use seed trays with a good seed-starting mix and provide consistent warmth (around 70-75°F) and bright light. A heat mat and grow light are highly recommended, especially given our often overcast spring days. Water gently from the bottom to avoid disturbing the tiny seeds.

Remember, celery is slow to get going, so be patient. Starting early indoors is key to getting a decent harvest before our weather starts to cool off again.

Transplant your celery seedlings outdoors from early to late May, once the danger of frost has passed. 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 celery plants 8-10 inches apart in a sunny spot that gets at least 4-6 hours of sunlight. Our mild summers mean they can tolerate full sun, but a little afternoon shade won't hurt. Make sure the soil is rich, well-draining, and consistently moist.

Keep an eye on the weather forecast around transplant time. Late frosts can still happen, so be prepared to cover your young plants if necessary.

Celery is extremely thirsty and needs consistently moist soil to thrive here in the Pacific Northwest. It's probably the most water-demanding vegetable you can grow. Even brief dry spells can lead to bitter, hollow stalks, so consistent watering is essential.

During our wet springs, you might not need to water as frequently, but once the dry summer months arrive, you'll need to water deeply and regularly. Aim for about 1-2 inches of water per week, depending on rainfall and soil drainage. Use the finger test: 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 to avoid wetting the foliage, which can help prevent fungal diseases in our humid climate. Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to root rot, so make sure your soil is well-draining. A layer of mulch around the plants can help retain moisture and suppress weeds.

You can expect your first celery harvest from late July through mid-September. Celery is ready to harvest when the outer stalks are at least 8 inches long. You can either 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 snap them off near the base of the plant. For a continuous harvest, focus on the outer stalks, allowing the inner stalks to continue growing. Some gardeners blanch their celery by mounding soil around the stalks a few weeks before harvest, which makes them milder.

As our first frost approaches in early October, harvest any remaining celery. Even though it's semi-hardy, a hard frost can damage the stalks.

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

Bolting from Temperature Stress

• What it looks like: The plant prematurely sends up a flower stalk, stopping stalk production and making them bitter.
• What causes it: Celery is sensitive to temperature fluctuations. A sudden cold snap or a period of unexpected heat can trigger bolting.
• How to fix/prevent it: Choose bolt-resistant varieties. Provide consistent moisture and protect plants from temperature extremes with row covers or shade cloth.

Hollow Stalks

• What it looks like: The center of the celery stalks are hollow.
• What causes it: Inconsistent watering or a lack of boron in the soil.
• How to fix/prevent it: Ensure consistent watering, especially during dry periods. Amend the soil with a boron supplement if a soil test indicates a deficiency.

Stringy Stalks from Heat

• What it looks like: The celery stalks are tough and have excessive stringy fibers.
• What causes it: Prolonged periods of heat stress during the growing season.
• How to fix/prevent it: Plant in a location with some afternoon shade. Ensure adequate watering and mulch to keep the soil cool. Choose varieties that are known to tolerate warmer temperatures.

Pacific Northwest Specific Challenges: Our mild heat and dry summer months can lead to watering challenges with Celery. Late blight can also be a factor with our wet springs. Consistent monitoring and proactive measures are key to a successful celery harvest in our region.

Companion planting can help your celery thrive in the Pacific Northwest garden.

Good companions for celery include:

• Green beans: They fix nitrogen in the soil, which benefits celery's growth.
• Cabbage: It deters cabbage white butterflies, a common pest in our region.
• Tomatoes: They provide shade, which can help protect celery from bolting during warm spells.
• Onions: They repel certain pests that might attack celery.

Avoid planting carrots near celery, as they compete for the same nutrients in the soil.