Sweet Peppers in Zone 6A — Mountain West

Sweet peppers are a fantastic addition to any high-altitude garden. Their sweet, crisp flavor is unmatched when homegrown, and they're incredibly versatile in the kitchen. Plus, there's a real sense of accomplishment in harvesting vibrant peppers you've nurtured yourself, knowing our cool nights even in summer enhance their sweetness.

Growing sweet peppers in our Mountain West climate presents unique challenges, including intense sun, alkaline soil, and a short growing season of about 153 days. But with careful timing and a few strategic techniques, you can absolutely enjoy a bountiful pepper harvest.

Starting sweet pepper seeds indoors is essential for us here in the Mountain West. With our short season, getting a head start is the only way to ensure a good harvest. Aim to sow your seeds mid-March through early April, about 8 weeks before you plan to transplant them outside.

Use seed trays or small pots filled with a good seed-starting mix. Keep the soil consistently moist, and consider bottom watering to avoid damping off. Place the trays in a warm spot, ideally around 75-80°F, and provide plenty of light. A grow light is highly recommended due to our late spring character and often cloudy conditions.

Transplanting sweet pepper seedlings outdoors should happen mid-May through mid-June, after the last expected frost. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them acclimate to the intense sun and cooler nights.

When transplanting, space your pepper plants 18-24 inches apart in a sunny spot with well-drained soil. Be mindful of potential late-season frosts or unexpected hail storms, which can still occur during this time. A row cover can offer protection if needed.

Consistent watering is key to growing sweet, thick-walled peppers in our dry Mountain climate. While our summers aren't brutally hot, the low humidity and dry rainfall mean supplemental watering is crucial. Aim for consistent moisture, but avoid waterlogging.

During the peak of summer, you'll likely need to water your pepper plants deeply 2-3 times per week, providing about 1-2 inches of water each time. Use the finger test – if the top 2 inches of soil feel dry, it's time to water. Water at the base of the plants to avoid wetting the foliage, which can help prevent fungal issues in our cool nights.

Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch, such as straw or wood chips, helps retain soil moisture and regulate soil temperature.

While not always necessary, providing support for your sweet pepper plants can be beneficial, especially as they become laden with fruit. Many bush-type varieties can get top-heavy, and our occasional strong winds can cause branches to break.

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. Cages also work well, providing all-around support. Choose the support method that best suits your pepper variety and your garden setup.

Pruning sweet peppers isn't essential, but a little strategic pinching can lead to stronger plants and a better harvest. In the early part of the season, pinch off the first few flower buds that appear. This encourages the plant to focus its energy on developing a strong root system and foliage.

Throughout the season, remove any yellowing or diseased leaves to improve airflow and prevent the spread of problems. As the end of our short season approaches (first frost around early October), you can remove any new flowers that form. This directs the plant's energy into ripening the existing peppers before the cold arrives.

You can expect your first sweet pepper harvest mid-July through early September, depending on the variety and the weather. Sweet peppers are typically ready to harvest about 65 days after transplanting. Look for peppers that have reached their full size and desired color for the variety.

The longer a sweet pepper ripens on the plant, the sweeter it becomes. To harvest, use pruning shears or a sharp knife to cut the pepper from the plant, leaving a short stem attached. Regular harvesting encourages continued production.

As the first frost approaches in early October, harvest any remaining peppers, even if they haven't fully ripened. Green peppers can be ripened indoors by placing them in a paper bag with an apple or banana.

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. Plant looks healthy but produces no fruit.
• What causes it: Temperature stress is often the culprit. Our fluctuating temperatures, especially cold nights, can inhibit fruit set. Low humidity can also contribute.
• How to fix/prevent it: Be patient – fruit set usually resumes when temperatures moderate. Provide afternoon shade during extreme heat. Ensure consistent watering.

Aphids

• What it looks like: Clusters of tiny soft-bodied insects (green, black, or white) on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: These sap-sucking pests thrive in warm weather, and our dry conditions can make them even more prevalent.
• How to fix/prevent it: A strong spray of water can knock them off. Encourage beneficial insects like ladybugs. Insecticidal soap or neem oil can be used for heavy infestations.

Sunscald

• What it looks like: White, papery patches on fruit exposed to direct sun. Affected areas may blister and become susceptible to rot.
• What causes it: Our intense UV radiation can damage fruit that's suddenly exposed to direct sunlight, especially after leaf loss.
• How to fix/prevent it: Avoid over-pruning foliage. Use shade cloth during periods of extreme heat. Ensure plants have healthy foliage to shade fruit naturally.

Blossom End Rot

• What it looks like: Sunken, dark brown or black leathery patch on the bottom (blossom end) of fruit.
• What causes it: Calcium deficiency caused by inconsistent watering. The dry spells followed by heavy watering we sometimes experience can disrupt calcium uptake.
• How to fix/prevent it: Water consistently. Mulch heavily to maintain even soil moisture. Remove affected fruit.

Mountain West Specific Challenges: The combination of intense UV radiation, low humidity, and dry rainfall in our Mountain climate can make sweet pepper growing a bit tricky. Consistent watering is paramount to prevent blossom end rot and ensure healthy fruit development. Providing afternoon shade during the hottest part of the day can help prevent sunscald.

Companion planting can enhance the growth and flavor of your sweet peppers. Tomatoes make excellent companions, as they share similar growing requirements and can provide some shade. Basil is another great choice, as it repels pests and attracts beneficial insects. Carrots and onions can also be planted nearby, as they don't compete for resources and can help deter certain pests. Spinach is a good ground cover, suppressing weeds and conserving moisture.

Avoid planting fennel, kohlrabi, or other brassicas (like cabbage and broccoli) near your sweet peppers. Fennel inhibits the growth of many plants, while kohlrabi and brassicas can attract pests that also affect peppers. By choosing the right companions, you can create a thriving and productive garden.