Celery in Zone 3B — Mountain West

Growing celery here in the Mountain West might seem ambitious, but the crisp, homegrown flavor is worth the effort. Plus, the intense sunlight and cool nights actually concentrate sugars, giving you a sweeter, more flavorful stalk than you'll find in any store. The satisfaction of harvesting your own celery, especially in our short season, is hard to beat.

Our high altitude, intense sun, and short growing season definitely present challenges. But with careful timing and attention, you can absolutely enjoy fresh celery from your garden. With a 108-day growing season, starting seeds indoors at the right time is key to success.

Start your celery seeds indoors in early to late March – about 10 weeks before you plan to transplant them outside. Use seed trays and a good seed-starting mix. Celery seeds are tiny and need light to germinate, so don't bury them too deep.

Keep the trays consistently moist. Bottom watering is great for this – set the tray in a shallow dish of water and let the soil soak it up. You'll also want to provide warmth, ideally around 70-75°F, and plenty of light. A grow light works wonders, especially with our late spring starts.

Remember, celery is slow to get going. Be patient and don’t give up if you don’t see sprouts immediately. Starting early is key in our short Mountain growing season, so you have the best chance of success.

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

Space the plants 8-10 inches apart in well-amended soil. Even in late May, we can still get some unexpected cold snaps, so keep an eye on the forecast and be prepared to cover your young plants if needed. Our alkaline soil benefits from added compost or other organic matter to help retain moisture.

Celery is a thirsty plant, and consistent moisture is crucial for success in our dry Mountain climate. You'll need to water frequently, especially during the hottest part of the summer. Aim to keep the soil consistently moist but not waterlogged.

Check the soil moisture regularly using the "finger test" – stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. In our dry climate, you'll likely need to water deeply several times a week, providing about 1-2 inches of water per week. Water at the base of the plants to avoid getting the foliage wet, which can help prevent fungal issues in our low-humidity environment.

Signs of underwatering include wilting leaves and bitter-tasting stalks. Overwatering can lead to root rot, so make sure your soil drains well. Mulching around your celery plants with straw or wood chips can help retain moisture in the soil and regulate soil temperature, which is especially helpful with our intense sun.

Your first celery harvest should be in mid August through mid September, about 85 days after transplanting. Look for outer stalks that are at least 8 inches long. You can harvest individual stalks as needed, cutting them off at the base of the plant.

Alternatively, you can harvest the entire plant when the stalks are 12 inches or longer. Just cut the whole thing off at the base. Some gardeners blanch celery stalks by mounding soil around them a few weeks before harvest; this reduces bitterness.

To encourage continued production, harvest the outer stalks first, leaving the inner stalks to continue growing. As the first frost approaches in early September, harvest any remaining celery to avoid frost damage.

Here are the top 3 problems you might face growing celery in the Mountain West:

Bolting from Temperature Stress

• What it looks like: The plant prematurely sends up a flower stalk, making the leaves and stalks bitter and inedible.
• What causes it: Fluctuating temperatures, especially cold snaps followed by warm spells, can stress the plant and trigger bolting. This is common in our region with our variable spring and early fall weather.
• How to fix/prevent it: Choose bolt-resistant varieties. Start seeds indoors to avoid early temperature swings. Provide shade during the hottest part of the day and protect plants from unexpected cold snaps with row covers.

Hollow Stalks

• What it looks like: The inside of the celery stalks are hollow and lack substance.
• What causes it: Inconsistent watering and nutrient deficiencies. Celery needs a steady supply of water and nutrients to develop properly. Our alkaline soil can also limit nutrient availability.
• How to fix/prevent it: Water deeply and consistently, especially during hot, dry periods. Amend the soil with compost and use a balanced fertilizer. Ensure the soil pH is slightly acidic to neutral for optimal nutrient uptake.

Stringy Stalks from Heat

• What it looks like: The celery stalks are tough, fibrous, and difficult to chew.
• What causes it: High temperatures, especially combined with low humidity, can cause the stalks to become stringy. While our summers are moderate-at-altitude, we still get some hot spells.
• How to fix/prevent it: Provide afternoon shade during the hottest part of the day. Ensure consistent watering to keep the plants cool. Harvest celery before it gets too mature, as older stalks tend to be more stringy.

Mountain West Specific Challenges: Our moderate-at-altitude heat, low humidity, and dry rainfall create a unique set of challenges for celery. Consistent watering is absolutely essential to prevent hollow and stringy stalks. The intense sun can also lead to bolting, so providing some afternoon shade is beneficial.

Companion planting can help your celery thrive. Green beans are great companions because they fix nitrogen in the soil, which celery loves. Cabbage benefits from celery's pest-repelling properties. Tomatoes provide shade and support for celery, while onions deter certain pests.

Avoid planting carrots near celery, as they compete for the same nutrients in the soil, and carrots can attract celery leaf miners.