Snow Peas in Zone 3A — Mountain West

Snow peas are a fantastic choice for the short growing season here in the Mountain West. Their crisp, sweet pods are delicious raw, stir-fried, or added to salads, and the plants themselves are beautiful climbers. There's real satisfaction in harvesting a generous supply of snow peas before the heat of summer really kicks in.

Our high altitude, intense sun, and cool nights can present challenges, but snow peas are a cool-season crop that thrives in these conditions if you time it right. With a 96-day growing season, you can easily squeeze in a crop of snow peas as long as you get them in the ground at the right time.

You can transplant snow peas outdoors from early May through early June. This gives you a head start, but direct sowing is often just as successful. Before transplanting, be sure to harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

When transplanting, space the seedlings 3-4 inches apart. Keep an eye on the weather forecast, as we can still get late frosts or even hail during this time of year. Protect your young plants with row covers if necessary.

Direct sowing is the preferred method for growing snow peas here in the Mountain West. Wait until the soil temperature reaches at least 45°F, generally from mid April through late June. Like garden peas, sow seeds directly into the soil as soon as it can be worked in the spring.

Prepare the soil by loosening it and adding compost. Plant seeds 1 inch deep and 3-4 inches apart. Keep the soil consistently moist until germination.

Snow peas need consistent moisture, especially during flowering and pod development. In our dry Mountain West climate, aim for about 1 inch of water per week, either from rainfall or irrigation. Use the finger test: stick your finger about 2 inches deep 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 encourage fungal diseases. Overhead watering is okay, but it's best to do it in the morning so the leaves have time to dry out during the day. Signs of underwatering include wilting leaves and stunted growth, while overwatering can lead to yellowing leaves and root rot.

A layer of mulch around the base of the plants helps retain moisture and keeps the soil cool, which is particularly important as summer approaches. Use straw, shredded leaves, or compost.

Snow peas are vining plants and need support to grow properly. A simple trellis made of string, netting, or wire works well. Because snow peas are lighter than snap peas, it doesn't need to be overly robust.

Install the trellis at planting time to encourage the plants to climb from the start. As the plants grow, gently guide the vines onto the trellis. They'll usually start grabbing on their own with their tendrils.

You can expect your first harvest of snow peas from mid June through mid September, about 55 days after planting. Harvest the pods when they are flat and you can just barely see the pea outlines inside. The pods should be translucent and crisp.

Harvest regularly to encourage continued production. Use scissors or snips to cut the pods from the vine, being careful not to damage the plant. As the end of the season approaches in early September, keep harvesting to get the most out of your plants before the first frost.

Here are a few common problems you might encounter growing snow peas in the Mountain West:

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems, and sometimes fruit. Leaves curl, yellow, and die.
• What causes it: Various fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it. The cool nights and warm days of our Mountain summers create ideal conditions.
• How to fix/prevent it: Improve air circulation through spacing and pruning. Remove affected leaves. Neem oil or potassium bicarbonate sprays help. Milk spray (1 part milk to 9 parts water) is surprisingly effective. Plant resistant varieties.

Pea Aphids

• What it looks like: Clusters of small, soft-bodied insects (green, yellow, or pink) on stems and leaves. Leaves may be curled, distorted, or yellowed.
• What causes it: Aphids are attracted to stressed plants. They suck plant sap, weakening the plant. They thrive in mild weather.
• How to fix/prevent it: Inspect plants regularly. Blast aphids off with a strong stream of water. Introduce beneficial insects like ladybugs and lacewings. Insecticidal soap or neem oil can be effective.

Root Rot

• What it looks like: Stunted growth, yellowing leaves, and wilting, even when the soil is moist. Roots are brown and mushy.
• What causes it: Overwatering and poorly drained soil. Fungal pathogens thrive in these conditions. Our alkaline soil can also contribute to root rot.
• How to fix/prevent it: Improve soil drainage by adding compost and avoiding overwatering. Ensure good air circulation around the plants. Use raised beds if necessary. Treat with a fungicide if detected early.

Fusarium Wilt

• What it looks like: Wilting on one side of the plant first, then spreading. Yellow leaves starting on one side. Brown streaks in stem when cut open.
• What causes it: Soil-borne fungus (Fusarium oxysporum). Persists in soil for years. Enters through roots. Warm soil temperatures favor it.
• How to fix/prevent it: No cure once infected – remove and destroy the plant. Plant resistant varieties (look for 'F' on seed labels). Rotate crops on a 4-year cycle. Solarize soil in hot zones. Raise soil pH above 6.5.

Mountain West Specific Challenges: Our intense sun can stress plants, making them more susceptible to pests and diseases. The low humidity can help prevent some fungal diseases, but it also means you need to be vigilant about watering. Hail can also damage snow pea plants, so consider using row covers for protection during severe weather.

Companion planting can help your snow peas thrive. Carrots and radishes are good companions because they loosen the soil, making it easier for snow peas to establish their roots. Cucumbers and corn provide a natural trellis for the snow peas to climb on, saving you space. Lettuce provides ground cover, which helps to retain moisture and suppress weeds.

Avoid planting snow peas near onions or garlic, as these can inhibit their growth. Onions and garlic secrete compounds into the soil that can stunt the growth of legumes like snow peas.