Sweet Peppers in Zone 7A — Mountain West

Sweet peppers are a rewarding addition to any high-altitude garden. Their crisp sweetness and vibrant colors shine in summer dishes. Here in the Mountain West, the intense sun and cool nights concentrate their flavors beautifully, making homegrown peppers far superior to anything you'll find at the store.

Growing sweet peppers in our region comes with challenges like a short growing season and intense UV radiation. But with careful timing and a few protective measures, you can enjoy a bountiful harvest within our 173-day growing season. Don't let the Mountain climate scare you; peppers are worth it.

Starting sweet pepper seeds indoors is essential for success in our short-season climate. Begin in early to late March, about eight weeks before you plan to transplant them outside. This gives them a head start before the weather warms.

Use seed trays with a good seed-starting mix. Provide consistent warmth (around 75-80°F) and plenty of light. A heat mat can be beneficial. Bottom watering is a great technique to keep the soil moist without damping off. Since our spring weather can be unpredictable, starting indoors gives your peppers the best chance to thrive.

Transplant your sweet pepper seedlings outdoors from early May through early June, after the last expected frost. 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.

Space your plants 18-24 inches apart in a sunny spot with well-draining soil. Keep an eye on the weather forecast. A late frost is always possible in the Mountains, so be ready to cover your transplants if needed.

Consistent watering is key to growing sweet, thick-walled peppers in our dry Mountain climate. Aim to keep the soil consistently moist, but not waterlogged. We receive only 10-20 inches of rainfall annually here, so supplemental watering is a must.

During the hot, dry summer months, you may need to water your peppers every few days. Stick your finger about two inches deep into the soil. If it feels dry, it's time to water. Give them about 1-2 inches of water per week, depending on the weather. Water at the base of the plants to avoid wetting the foliage, which can lead to fungal issues in other regions, though our low humidity usually prevents this.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to yellowing leaves and root rot. A good layer of mulch, like straw or wood chips, can help retain moisture and regulate soil temperature, critical in our region's intense sun.

While not always necessary, providing support for your sweet pepper plants can be beneficial, especially as they become laden with fruit. Some varieties get quite large and can topple over.

Staking is a simple and effective method. Insert a sturdy stake near each plant at planting time, and gently tie the main stem to the stake as it grows. Tomato cages also work well, providing all-around support. This prevents branches from breaking and keeps the fruit off the ground.

Pinching off the first few flowers that appear on your sweet pepper plants encourages stronger root development and leads to a higher overall yield. This is especially helpful in our short growing season.

Simply remove the first set of flowers as soon as you see them. Throughout the season, you can also remove any yellowing or dead leaves. As the first frost approaches in early October, you can remove any small, immature peppers to encourage the plant to put its energy into ripening the larger ones.

You can expect your first sweet pepper harvest from early July through late August, about 65 days after transplanting. Peppers are ready to harvest when they've reached their full size and color for the variety. They get sweeter the longer they ripen on the plant.

To harvest, use sharp scissors or pruning shears to cut the stem just above the pepper. Avoid pulling, as this can damage the plant. Regular harvesting encourages continued production. As the first frost nears in early October, harvest any remaining peppers, even if they're still green. They can ripen indoors in a paper bag or on a sunny windowsill.

Here are some common problems you might encounter growing sweet peppers in the Mountain West:

Blossom Drop

• What it looks like: Flowers fall off without setting fruit. Small fruit yellows and drops. The plant looks healthy but produces no fruit.
• What causes it: Temperature stress is the main culprit. Peppers don't set fruit well when nights stay above 75°F. Our cool nights usually prevent this, but daytime heat can still be an issue. Low humidity and poor pollination can also contribute.
• How to fix/prevent it: Be patient — fruit set often resumes when temperatures moderate. Provide afternoon shade during extreme heat. Keep plants well-watered. Gently shake the plants to encourage pollination.

Aphids

• What it looks like: Clusters of tiny insects (green, black, or white) on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: Rapid-reproducing sap-sucking insects. Populations explode in warm weather.
• How to fix/prevent it: A strong water spray can knock them off. Encourage ladybugs and lacewings (natural predators). Insecticidal soap works well. Avoid excess nitrogen fertilizer.

Sunscald

• What it looks like: White, papery patches on fruit exposed to direct sun. Affected areas may blister.
• What causes it: Intense, direct sunlight on fruit, especially after leaves are lost. Our high altitude and intense UV radiation make this a real risk.
• How to fix/prevent it: Don't over-prune foliage. Use shade cloth in extreme heat. If fruit is already exposed, drape a small piece of row cover over it.

Blossom End Rot

• What it looks like: Sunken, dark brown or black leathery patch on the bottom of the fruit.
• What causes it: Calcium deficiency caused by inconsistent watering. Common in our region due to our dry climate and alkaline soil.
• How to fix/prevent it: Water consistently. Mulch heavily to maintain even soil moisture. Remove affected fruit.

Mountain West Specific Challenges: Our high altitude and intense sun can exacerbate issues like sunscald and blossom drop. The dry climate and alkaline soil make consistent watering and soil amendments crucial for healthy pepper growth. Be vigilant and adjust your gardening practices to suit our unique conditions.

Companion planting can boost your sweet pepper crop in the Mountain West. Tomatoes make excellent companions because they share similar needs for sun, water, and nutrients. Basil repels pests and attracts pollinators, benefiting your peppers. Carrots loosen the soil and improve drainage. Onions deter certain pests. Spinach provides ground cover, helping to retain moisture and suppress weeds.

Avoid planting fennel near your peppers, as it inhibits their growth. Kohlrabi and other brassicas (like cabbage and broccoli) can compete for nutrients and attract pests that also target peppers. Proper companion planting can create a healthier and more productive garden.