Celery in Zone 6A — Mountain West

Celery, with its crisp texture and refreshing flavor, is a rewarding challenge for the Mountain West gardener. Fresh, homegrown celery elevates everything from soups and salads to simple snacks, offering a taste far superior to anything you'll find at the grocery store. Plus, those cool nights we get, even in summer, really help to develop the best flavor.

Growing celery here in our Zone 6A climate definitely requires some planning. Our high altitude, intense sun, and short 153-day growing season demand a head start. But with careful timing and attention, you can absolutely enjoy a successful celery harvest before the first frost hits in early October.

Starting celery indoors is essential in our region due to the short growing season. Begin your seeds indoors from mid-February through early March, about 10 weeks before you plan to transplant. This gives the slow-growing celery seedlings a much-needed head start.

Use seed trays filled with a good seed-starting mix. Celery seeds are tiny and need light to germinate, so don't bury them too deep; just gently press them into the surface. Keep the soil consistently moist – bottom watering is ideal to avoid disturbing the delicate seeds. Place the trays in a warm location (around 70-75°F) under grow lights. Remember our late springs here; those extra weeks indoors are crucial.

Transplant your celery seedlings outdoors from early to late May, after the danger of hard frost has passed. Before transplanting, harden off the seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense sun and cooler temperatures of the Mountain West.

Choose a location with full sun to partial shade, and space the plants 8-10 inches apart. Our spring weather can be unpredictable, so watch out for late frosts and be prepared to cover your seedlings if necessary. A little protection early on makes a big difference.

Celery is a thirsty plant, and consistent watering is key to success in our dry Mountain West climate. Due to our low humidity and limited rainfall (10-20 inches annually), you'll need to be diligent about irrigation. Aim to keep the soil consistently moist but not waterlogged.

During the hotter summer months, from late June through August, you'll likely need to water deeply every 2-3 days. Use the finger test: stick your finger about 2 inches into the soil. If it feels dry, it's time to water. Provide about 1-2 inches of water per week, either through drip irrigation or by watering at the base of the plants to avoid wetting the foliage, which can encourage fungal issues, even in our dry climate.

Signs of underwatering include wilting leaves and bitter-tasting stalks. Overwatering can lead to root rot, so be sure your soil drains well. Applying a layer of mulch around the plants can help retain moisture and regulate soil temperature, which is especially helpful with our intense sun.

You can expect your first celery harvest from late July through mid-September, about 85 days after transplanting. Look for stalks that are at least 8 inches long to harvest individual outer stalks. For a larger harvest, you can 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 from the base of the plant. This allows the remaining stalks to continue growing, providing a continuous harvest. As the first frost approaches in early October, harvest any remaining celery. You can wrap the stalks in damp paper towels and store them in the refrigerator for several weeks.

Here are some common problems you might encounter growing celery in the Mountain West:

Bolting from Temperature Stress

• What it looks like: The plant prematurely sends up a flower stalk, making the celery stalks bitter and inedible.
• What causes it: Fluctuations in temperature, especially cold snaps or sudden heatwaves, trigger bolting. This is common in our region with our unpredictable weather patterns.
• How to fix/prevent it: Choose bolt-resistant varieties. Provide consistent watering and mulch to regulate soil temperature. If a cold snap is predicted, cover your plants with row covers or blankets.

Hollow Stalks

• What it looks like: The center of the celery stalk is hollow and lacks substance.
• What causes it: Inconsistent watering or nutrient deficiencies, especially a lack of boron. Our alkaline soil can sometimes lock up nutrients, making them unavailable to the plants.
• How to fix/prevent it: Ensure consistent watering, especially during hot, dry periods. Amend your soil with compost to improve nutrient availability. Consider a foliar spray of diluted seaweed extract to provide trace minerals.

Stringy Stalks from Heat

• What it looks like: The celery stalks are tough, fibrous, and difficult to chew.
• What causes it: High temperatures and lack of moisture can cause the stalks to become stringy. While our summers are moderate-at-altitude, the intense sun can still stress the plants.
• How to fix/prevent it: Provide afternoon shade during the hottest part of the day. Ensure consistent watering and mulch to keep the soil cool and moist. Choose varieties that are more heat-tolerant.

Mountain West Specific Challenges: Our moderate-at-altitude summer heat, combined with low humidity and dry rainfall, means that consistent watering and protection from intense sun are crucial for growing celery successfully here. Be prepared to monitor your plants closely and adjust your watering schedule as needed.

Companion planting can be a great way to boost your celery crop in the Mountain West. Green beans make excellent companions because they fix nitrogen in the soil, which celery needs to thrive. Cabbage also works well, as it can help deter some common celery pests.

Tomatoes and onions are also good companions, as they release compounds that can deter pests and improve celery growth. Avoid planting carrots near celery, as they compete for the same nutrients in the soil, hindering the growth of both plants.