Celery in Zone 8B — Southern California

Celery, with its crisp stalks and refreshing flavor, is a rewarding crop to grow here in Southern California. Fresh, homegrown celery is far superior to anything you'll find at the store, and it's a versatile addition to soups, salads, and snacks. Plus, our mild winters and long growing season give you a real head start.

While we face challenges like drought and intense summer heat inland, careful planning and water-wise gardening practices make growing celery possible. Our long, warm season that stretches nearly year-round gives us a long window to get it right.

Starting celery indoors is crucial for SoCal gardeners because it gives the seedlings a head start before our summer heat inland kicks in. Begin sowing seeds from late November through late December—about 10 weeks before you plan to transplant. Celery seeds are tiny and need light to germinate, so don't bury them too deep.

Use seed trays with a good seed-starting mix, keep them consistently moist (bottom watering works great to avoid disturbing the seeds), and provide warmth and bright light. A sunny windowsill or grow lights will do the trick. Remember, we have a very-early spring here, so getting these started early is key.

Transplant your celery seedlings outdoors from mid February through mid March, after they've developed several true leaves. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind, preventing shock.

Space the seedlings 8-10 inches apart in well-prepared soil. Even though it's still relatively mild, be mindful of any late cold snaps that might surprise us.

Celery is a thirsty plant, and consistent watering is vital for success, especially with our hot summer heat inland. You'll need to keep the soil consistently moist, but not waterlogged. Aim for about 1-2 inches of water per week, adjusting based on rainfall and temperature. During the hottest parts of the summer, inland, you may need to water daily.

The "finger test" is your best friend – stick your finger about 2 inches into the soil. If it feels dry, it's time to water. Water at the base of the plants to avoid wetting the foliage, which can lead to fungal issues in our low-to-moderate humidity. Signs of underwatering include wilting and bitter stalks, while overwatering can cause root rot.

Mulching around your celery plants with organic matter like straw or wood chips can help retain moisture in the soil, which is crucial with our water restrictions and dry climate.

You can expect your first harvest of celery from mid May through late June, about 85 days after transplanting. Look for stalks that are at least 8 inches long, and harvest the outer stalks first, allowing the inner ones to continue growing. Alternatively, you can cut the entire plant at the base when the stalks are 12 inches or longer.

Harvesting outer stalks encourages continued production, giving you a longer harvest window. As our first frost approaches in early December, harvest any remaining celery, as it won't tolerate freezing temperatures.

Celery can be a bit finicky, and here are some common problems we see in Southern California:

Bolting from temperature stress

• What it looks like: The plant prematurely sends up a flower stalk, and the stalks become bitter and tough.
• What causes it: Fluctuations in temperature, especially early warmth followed by a cold snap, can trigger bolting. This is especially true with our early spring character.
• How to fix/prevent it: Choose bolt-resistant varieties, provide consistent watering, and protect plants from temperature extremes with shade cloth or row covers during unexpected temperature swings.

Hollow stalks

• What it looks like: The center of the celery stalk is empty or has large air pockets.
• What causes it: Inconsistent watering and nutrient deficiencies, particularly calcium deficiency. This is common during our periods of drought and water restrictions.
• How to fix/prevent it: Ensure consistent watering, especially during hot weather. Amend the soil with compost and consider adding a calcium supplement like bone meal or crushed eggshells.

Stringy stalks from heat

• What it looks like: The stalks become tough and fibrous, making them unpleasant to eat.
• What causes it: High temperatures, especially during the summer heat inland, can cause the stalks to become stringy.
• How to fix/prevent it: Provide afternoon shade during the hottest part of the day. Consistent watering is also key to preventing this.

Southern California Specific Challenges: Our hot, dry summers inland combined with low-to-moderate humidity and occasional Santa Ana winds mean that celery needs extra attention to thrive. Consistent watering, shade during the hottest part of the day, and protection from temperature swings are all crucial for success.

Companion planting can help your celery thrive. Green beans are good companions because they fix nitrogen in the soil, which celery needs. Cabbage helps deter pests, and tomatoes offer shade during the hottest part of the day. Onions also deter pests that might bother your celery.

Avoid planting celery near carrots, as they compete for the same nutrients in the soil, hindering the growth of both plants.