Celery in Zone 5A — Mountain West

Celery, with its crisp texture and refreshing flavor, adds a unique dimension to our high-altitude gardens. It's a rewarding challenge, and homegrown celery beats anything you'll find at the store. The satisfaction of harvesting those crunchy stalks, knowing they thrived despite our cool nights and intense sun, is a special treat for Mountain gardeners.

Growing celery in our Zone 5A climate definitely has its hurdles. Between the short growing season of 138 days and the temperature swings, timing is everything. But by starting early and paying attention to its needs, you can absolutely enjoy homegrown celery before the first frost hits.

To get a jump start on our short growing season, start your celery seeds indoors from late February through mid March. This gives them about 10 weeks to get a strong start before transplanting. Celery seeds are tiny and need light to germinate, so don't bury them too deep.

Use seed trays filled with a good seed-starting mix and keep them consistently moist. Bottom watering can help prevent damping off. Place the trays in a warm location, ideally around 70-75°F, and provide plenty of light. A grow light is really helpful, especially with our late spring starts.

Remember, celery is slow to get going, so be patient. Germination can take a couple of weeks. Once the seedlings emerge, keep them well-lit and watered. Our cool spring nights make it all the more important to get those seedlings strong indoors.

Transplant your celery seedlings outdoors from early May through early June, once the danger of hard frost has passed. Before planting, harden them off for about a week by gradually exposing them to outdoor conditions. This helps them adjust to the intense sun and cooler temperatures that are common here in the Mountain West.

Choose a spot with full sun to partial shade, and space the seedlings 8-10 inches apart. Our unpredictable weather this time of year means you might need to cover them if a late frost threatens.

Celery is incredibly thirsty, and consistent moisture is key to preventing bitter, hollow stalks. This is especially crucial in our dry, low-humidity Mountain climate, where rainfall is scarce, and the intense sun can quickly dry out the soil. You need to water consistently.

During the peak of summer, from late June through August, you'll likely need to water deeply every other day, providing at least 1-2 inches of water per week. Use the finger test to check the soil moisture 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 and reduce the risk of fungal diseases in our dry climate.

Underwatering will result in stunted growth and bitter, hollow stalks. Overwatering, on the other hand, can lead to root rot, especially in heavy alkaline soil. Signs of underwatering include wilting leaves and dry soil. Yellowing leaves and soggy soil indicate overwatering. Mulching around the plants with straw or wood chips can help retain moisture and regulate soil temperature, which is especially beneficial with our intense UV and cool nights.

You can expect your first celery harvest from early August through late September, about 85 days after transplanting. Look for outer stalks that are at least 8 inches long. These are ready to harvest.

To harvest, simply cut the outer stalks near the base of the plant with a sharp knife. Leave the inner stalks to continue growing for a continuous harvest. Alternatively, you can cut the entire plant at the base when the stalks are 12+ inches long.

As our first frost approaches in late September, harvest any remaining celery to prevent damage. If you want milder stalks, blanch them by mounding soil around the base of the plants a week or two before harvesting. This blocks sunlight and reduces bitterness.

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 prematurely sends up a flower stalk, and the stalks become bitter and inedible.
• What causes it: Fluctuating temperatures, especially early in the season when we have those temperature swings.
• How to fix/prevent it: Choose bolt-resistant varieties. Use row covers to protect young plants from temperature fluctuations. Consistent watering also helps reduce stress.

Hollow Stalks

• What it looks like: The stalks are hollow inside, often accompanied by a bitter taste.
• What causes it: Inconsistent watering and nutrient deficiencies. Our dry climate and alkaline soil exacerbate this issue.
• How to fix/prevent it: Ensure consistent and deep watering, especially during hot weather. Amend your soil with compost to improve water retention and provide essential nutrients.

Stringy Stalks from Heat

• What it looks like: The stalks are tough and stringy, making them unpleasant to eat.
• What causes it: High temperatures, especially during the peak of summer.
• How to fix/prevent it: Provide afternoon shade during the hottest part of the day. Consistent watering and mulching can also help keep the soil cool.

Mountain West Specific Challenges: Our moderate-at-altitude heat combined with low humidity and dry rainfall means that consistent watering is absolutely essential for celery. The intense UV light can also stress the plants, so providing some afternoon shade or using row covers can be beneficial.

Companion planting can really help your celery thrive. Green beans are great companions because they fix nitrogen in the soil, which celery needs. Cabbage benefits from celery's pest-repelling properties. Tomatoes and onions also deter pests that might bother your celery.

Avoid planting carrots near celery. Carrots and celery compete for the same nutrients in the soil, which can stunt the growth of both plants.