Celery in Zone 5B — Mountain West

Growing celery in our Mountain West gardens might seem ambitious, but the crisp, homegrown flavor is worth the effort. Fresh celery adds a unique zest to soups, salads, and snacks, and the satisfaction of harvesting your own is hard to beat. Plus, those cool nights we get even in summer actually help develop a sweeter, milder flavor.

Our short growing season and intense sun definitely present challenges, but with careful timing and attention, you can absolutely grow celery here. Our 149-day season means starting early indoors is essential, so you can get your plants established before our first frosts arrive.

Starting celery indoors is a must in our region, since we need to get a head start. Plan to sow your seeds mid-February through early March, giving them about 10 weeks to develop before transplanting. Celery seeds are tiny and need light to germinate, so don't bury them too deeply – just gently press them into the surface of your seed-starting mix.

Use seed trays or small pots filled with a good quality seed-starting mix. Keep the soil consistently moist; bottom watering is a great way to prevent damping off. Place the trays in a warm location (around 70-75°F) with plenty of light. Remember, our springs here in the high altitude Mountain West are late, so patience is key!

Transplant your celery seedlings outdoors early May through early June, after the danger of hard 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 intense sun and cooler temperatures we often experience at this altitude.

Space your celery plants about 8-10 inches apart in a location that receives full sun to partial shade. Even though we have intense sun, celery can benefit from some afternoon shade, especially in the hottest part of the summer. Keep an eye on the weather forecast – late spring hail can damage young plants, so be prepared to cover them if needed.

Celery is extremely thirsty, and consistent watering is crucial, especially in our dry Mountain West climate. Unlike some other vegetables, celery can't tolerate even brief dry spells. Aim for consistently wet soil, as even short periods of dryness can result in hollow, bitter stalks.

During the peak of summer, when temperatures reach around 85°F, your celery might need up to 2 inches of water per week, maybe more. Use the finger test – 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 helps prevent fungal diseases in our low humidity environment.

Signs of underwatering include wilting leaves and stunted growth, while overwatering can lead to yellowing leaves and root rot. Mulching around your celery plants with straw or wood chips can help retain moisture and regulate soil temperature, which is especially helpful with our intense sun.

You can expect your first celery harvest late July through mid-September, about 85 days after transplanting. Look for stalks that are at least 8 inches long. You can harvest individual outer stalks as needed, allowing the inner stalks to continue growing.

To harvest, simply use a sharp knife to cut the outer stalks close to the base of the plant. Alternatively, you can cut the entire plant at the base when the stalks are 12 inches or longer. Some gardeners blanch their celery by mounding soil around the stalks a few weeks before harvest; this reduces bitterness and creates milder flavor.

As our first frost approaches in early October, harvest any remaining celery. Celery is semi-hardy, but a hard freeze will damage the stalks. You can store harvested celery in the refrigerator for several weeks.

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

Bolting from Temperature Stress

• What it looks like: The plant sends up a flower stalk prematurely, and the stalks become bitter and tough.
• What causes it: Fluctuations in temperature, especially cold snaps after a period of warmth, can trigger bolting. Our high altitude and unpredictable weather can make this a challenge.
• How to fix/prevent it: Choose bolt-resistant varieties. Use row covers or shade cloth during periods of temperature swings. Ensure consistent watering and avoid stressing the plants.

Hollow Stalks

• What it looks like: The celery stalks develop a hollow center, making them less desirable.
• What causes it: Inconsistent watering and nutrient deficiencies are common culprits.
• How to fix/prevent it: Provide consistent, even watering, especially during hot, dry periods. Amend your soil with compost before planting to improve its water-holding capacity and nutrient content. Consider side-dressing with a balanced fertilizer.

Stringy Stalks from Heat

• What it looks like: The celery stalks become tough and stringy, making them less palatable.
• What causes it: Prolonged exposure to high temperatures can cause stringiness.
• How to fix/prevent it: Provide afternoon shade to your celery plants. Ensure adequate watering to keep the plants cool and hydrated. Harvest promptly when the stalks reach maturity.

Mountain West Specific Challenges: Our moderate-at-altitude heat, low humidity, and dry rainfall patterns mean that consistent watering and protection from temperature extremes are crucial for successful celery growing. Monitor your plants closely and adjust your care as needed to address these challenges.

Companion planting can help your celery thrive in our Mountain West gardens. Green beans are a great companion because they fix nitrogen in the soil, benefiting celery's heavy feeding needs. Cabbage also works well, as its strong scent can deter some pests that bother celery.

Tomatoes can provide beneficial shade during our intense summer sun, helping to prevent bolting and stringy stalks. Onions are another good choice, as they repel certain pests. Avoid planting carrots near celery, as they compete for the same nutrients in our often-alkaline soil.