Snow Peas in Zone 6B — Mountain West

Snow peas are a fantastic addition to any Mountain West garden. Their crisp, sweet pods are delicious raw, stir-fried, or added to salads, and they thrive in our cool spring and fall weather. Plus, there's nothing quite like the satisfaction of harvesting fresh veggies from your own backyard, especially knowing how much better they taste than what you find at the store.

Our high altitude, intense sun, and short growing season in Zone 6B present some unique challenges. But with careful timing, you can enjoy a bountiful harvest of snow peas within our 163-day growing season. The key is to take advantage of our cool nights, which actually enhance the flavor of many vegetables.

You can transplant snow peas outdoors from late March through late April, giving them a head start on the growing season. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense UV and fluctuating temperatures of the Mountain West.

When transplanting, space the seedlings 3-4 inches apart and provide support for their vining growth habit. Keep an eye on the weather forecast, as late frosts can still occur during this time. Be prepared to cover your transplants with frost cloth if temperatures dip below freezing.

Direct sowing is the preferred method for planting snow peas, especially in our short season. You can start sowing seeds directly into the garden from mid-March through late July, ensuring a continuous harvest. Like garden peas, snow peas prefer cool soil, so early spring is ideal.

Before sowing, prepare the soil by loosening it and adding compost to improve drainage and fertility. Snow peas aren't too picky but do best in soil around 6.0 to 7.0 pH. Sow seeds 1 inch deep and 3-4 inches apart. Keep the soil consistently moist until germination, which usually takes about a week.

Snow peas need consistent moisture, especially during flowering, but they don't like soggy soil. In our dry Mountain West climate, you'll likely need to water them regularly, especially during the warmer months. Even though our summer highs are moderate-at-altitude, the low humidity means the soil dries out quickly.

A good rule of thumb is to water deeply about once a week, providing around 1 inch of water. 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 can encourage fungal diseases in our cool nights.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to yellowing leaves and root rot. Mulching around the plants with straw or wood chips can help retain moisture and regulate soil temperature.

Snow peas are vining plants and need support to grow properly. A simple trellis made of string, netting, or wire works perfectly well, since they are lighter than snap peas. You can also use pea brush (branches stuck in the ground).

Install the support at planting time, so the plants can start climbing as soon as they emerge. Gently guide the vines onto the support as they grow, and they'll quickly take hold. The support will also improve air circulation, which helps prevent fungal diseases.

You can expect your first harvest of snow peas from early May through mid-October, about 55 days after planting. The best time to harvest is when the pods 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. Simply snip the pods off the vine with scissors or your fingers, being careful not to damage the plant. As the first frost approaches in early October, harvest all remaining pods, even if they're not quite fully mature. They'll still be delicious!

Here are some 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. In the Mountain West, cool nights combined with intense sun during the day 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, pink, or white) on stems and undersides of leaves. Leaves may be curled, distorted, or yellowed. Sticky honeydew on leaves.
• What causes it: Aphids are attracted to stressed plants. In the Mountain West, this can be caused by inconsistent watering or nutrient deficiencies due to our alkaline soils.
• How to fix/prevent it: Blast aphids off plants with a strong stream of water. Introduce beneficial insects like ladybugs and lacewings. Insecticidal soap or neem oil can also be effective.
• Root Rot
• What it looks like: Stunted growth, yellowing leaves, wilting, and mushy brown roots.
• What causes it: Overwatering and poor soil drainage create conditions favorable for fungal pathogens. Our heavy clay soils in some areas of the Mountain West can exacerbate this problem.
• How to fix/prevent it: Improve soil drainage by adding compost and other organic matter. Avoid overwatering. Plant in raised beds if necessary. Use a fungicide if the problem is severe.
• 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: The intense sun at our high altitude can stress snow peas, making them more susceptible to pests and diseases. Low humidity and dry rainfall mean you need to be diligent about watering. Also, our alkaline soils can limit nutrient availability, so amending with compost is essential. Finally, be prepared for hail, which can damage the pods and leaves.

Companion planting can help your snow peas thrive in the Mountain West. Carrots and radishes are good companions because they loosen the soil and improve drainage, which is beneficial in our sometimes heavy clay soils. Cucumbers and corn provide shade, protecting the snow peas from the intense sun. Lettuce is a good ground cover that helps retain moisture and suppress weeds.

Avoid planting snow peas near onions and garlic, as they can inhibit their growth. These alliums are allelopathic, meaning they release chemicals into the soil that can harm other plants.