Snap Peas in Zone 7A — Mountain West

Snap peas are a Mountain West garden winner. Their crisp, sweet pods are delicious raw, stir-fried, or added to salads. Plus, they’re super satisfying to grow in our short season, offering a burst of fresh flavor when you need it most.

Our high altitude and intense sun can be tough on some crops, but snap peas are surprisingly resilient. With smart timing and attention to watering, you can easily squeeze in a couple of harvests during our 173-day growing season.

If you're starting snap peas indoors, transplant them outdoors from late March through mid April. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense sun and cool nights.

Space your transplants 3-4 inches apart. At this time of year, our weather can be unpredictable, so keep an eye on the forecast. Be prepared to cover your young plants with row covers if a late frost threatens.

Direct sowing is the easiest and most common way to grow snap peas in our region. Sow seeds directly into the garden from early March through late July. Snap peas, like their garden pea cousins, thrive when direct sown in the cool soil of early spring.

Before planting, make sure your soil is well-drained and loose. While our soils tend to be alkaline, snap peas are fairly adaptable. Sow seeds about 1 inch deep and 3-4 inches apart. Keep the soil consistently moist until germination, which usually takes about a week.

Consistent watering is key to plump, sweet snap pea pods, especially given our dry Mountain West climate. While snap peas are more tolerant of heat than shell peas, they still need consistent moisture to thrive in our moderate-at-altitude summer heat.

During the spring and fall, when temperatures are cooler, aim for about 1 inch of water per week. In the peak of summer, you might need to increase that to 1.5 inches, especially if you're experiencing a dry spell. The "finger test" is your friend: stick your finger about 2 inches into the soil near your plants. If it feels dry, it's time to water.

Water at the base of the plants to avoid wetting the foliage, which, despite our low humidity, can still encourage fungal issues. Signs of underwatering include wilting leaves and small, underdeveloped pods. Overwatering, on the other hand, can lead to yellowing leaves and root rot. A layer of mulch, like straw or wood chips, can help retain moisture and regulate soil temperature, which is especially important with our intense sun.

Snap peas are vining plants and need support to climb. A trellis is ideal, allowing the plants to grow vertically and maximizing your garden space.

Install your trellis at planting time to avoid disturbing the roots later. A simple string trellis, chicken wire attached to posts, or even repurposed branches ("pea brush") will work. Aim for a trellis that's 4-6 feet tall. As the plants grow, gently guide the vines onto the support.

You can expect your first harvest of snap peas from early May through mid October, depending on when you planted. Snap peas are usually ready to harvest about 60 days after planting.

Harvest when the pods are plump and crisp, with fully developed peas inside. The entire pod is edible. Pick them when they're young and tender for the best flavor. Gently snap the pods off the vine, being careful not to damage the plant. Regular harvesting encourages continued production.

As our first frost approaches in early October, harvest any remaining pods, even if they're not quite fully ripe. You can still enjoy them in stir-fries or soups.

Here are a few common problems to watch out for with snap peas in our region:

Powdery Mildew

• What it looks like: A white or grayish powdery coating on leaves, stems, and sometimes pods. Leaves may 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, which is why we see it even in our low-humidity climate.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning if needed. Remove affected leaves promptly. Neem oil or potassium bicarbonate sprays can help. A milk spray (1 part milk to 9 parts water) can also be effective. Plant resistant varieties.

Pea Aphids

• What it looks like: Clusters of small, soft-bodied green insects on stems, leaves, and pods. They can cause distorted growth and sticky honeydew.
• What causes it: Aphids are attracted to stressed plants. They thrive in warm weather and can multiply rapidly.
• How to fix/prevent it: Regularly inspect plants for aphids. Blast them off with a strong stream of water from the hose. Introduce beneficial insects like ladybugs and lacewings. Insecticidal soap or neem oil can be used as a last resort.

Root Rot

• What it looks like: Yellowing leaves, stunted growth, and wilting, even when the soil is moist. Roots are brown and mushy.
• What causes it: Fungi that thrive in overly wet soil. Poor drainage and overwatering are common culprits.
• How to fix/prevent it: Ensure good soil drainage. Avoid overwatering. Plant in raised beds if necessary. Improve soil structure by adding compost.

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 the stem when cut open.
• What causes it: A soil-borne fungus (Fusarium oxysporum). It persists in the soil for years and enters through the 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 the soil in hot zones. Raise the soil pH above 6.5.

Mountain West Specific Challenges: Our intense sun can stress plants, making them more susceptible to pests and diseases. While our low humidity helps prevent some fungal issues, it also means that plants dry out quickly, increasing the risk of underwatering. Be vigilant about monitoring your plants and adjusting your watering schedule as needed. Hail can also be a concern, so consider using netting to protect your crop if hailstorms are common in your area.

Snap peas benefit from companion planting. Carrots and radishes loosen the soil, making it easier for pea roots to penetrate. Cucumbers and corn provide shade during our intense summer sun, which helps keep the soil cool and moist. Lettuce acts as a living mulch, suppressing weeds and retaining moisture.

Avoid planting snap peas near onions and garlic. These alliums can inhibit pea growth.