How to Grow Sweet Peppers in Your Greenhouse

Sweet peppers are a rewarding addition to any greenhouse garden. Their vibrant colors, crisp textures, and sweet flavors make them a favorite among home gardeners and chefs. 

To grow these versatile veggies successfully, your greenhouse needs the right combination of care and strategy. 

Follow these 7 practical tips to grow healthy, productive pepper plants and enjoy a delicious summer harvest.

Let’s dig in!

1. Choose the Right Sweet Pepper Varieties

The first step to a successful greenhouse harvest is selecting the right pepper varieties:

  • Sweet peppers like bell peppers, sweet banana peppers, and mini sweet peppers are all excellent choices. 
  • Bell peppers offer classic versatility, while banana peppers bring a unique shape and mild flavor. 
  • Mini sweet peppers are perfect for snacking or adding vibrant color to your dishes. 

Look for disease-resistant seeds labeled for greenhouse cultivation to ensure they thrive in controlled conditions. 

The variety you choose impacts flavor, size, and growth requirements, so consider your preferences before planting.

Choosing the right varieties ensures a productive and flavorful harvest.

2. Create the Ideal Growing Conditions

Sweet peppers thrive in warm, sunny environments, making greenhouses the perfect space: 

  • They prefer daytime temperatures between 70–85°F and nighttime temperatures above 60°F. 
  • To replicate these conditions, consider using a greenhouse thermometer and ventilation systems to maintain consistency. 
  • Plant your peppers in nutrient-rich, well-draining soil with a pH of 6.0–7.0, and water them regularly, keeping the soil moist but not waterlogged. 
  • Provide 6–8 hours of sunlight daily, supplementing with grow lights if needed. You’ll support healthy growth and maximize yields by giving your plants the right environment.

Maintaining stable temperatures and light levels is key to healthy pepper plants.

3. Start Indoors and Transplant with Care

If starting from seed, begin indoors about 8–10 weeks before your region's last frost date. Seeds require consistent warmth to germinate, so a heated seedling mat can speed up the process. 

Once your seedlings have grown sturdy stems and several true leaves, it’s time to harden them off. 

Gradually expose them to outdoor conditions by placing them outside for a few hours a day over a week. This helps prevent transplant shock. 

When planting in your greenhouse, space your peppers 18–24 inches apart for proper airflow, which reduces the risk of disease.

4. Fertilize and Prune for Healthy Growth

Sweet peppers are nutrient-hungry plants and benefit from regular feeding: 

  • Use a balanced fertilizer, such as 10-10-10, or a slow-release option to supply steady nutrients throughout the growing season. 
  • Pruning your pepper plants can also enhance their productivity. 
  • Remove suckers—the small shoots that grow between the main stem and branches—to direct the plant’s energy toward fruit production. 
  • Trim any yellowing or damaged leaves, as they can drain resources and invite pests. 
  • Consider staking or tying the stems for larger pepper varieties to provide extra support as the plants grow and fruit develops.

Staking pepper plants prevents stems from bending under the weight of fruit.

5. Manage Pests Naturally with Companion Planting

Pests like aphids can damage pepper plants, but you don’t need harsh chemicals to control them. Companion planting with green onions is a proven, natural way to deter aphids. 

In our Facebook group, one gardener recommends planting store-bought green onions beneath your peppers. 

Simply cut the tops, soak the roots in water until they sprout, and plant them under your pepper plants. 

This method repels pests, and you’ll enjoy a bonus harvest of green onion tops for your kitchen. Healthy plants and fewer pests—what’s not to love?

6. Harvest Sweet Peppers at Peak Ripeness

Knowing when to pick your peppers can make all the difference in flavor and quality: 

  • Peppers are ready to harvest when they are firm, glossy, and have reached their full size. 
  • If you prefer green peppers, harvest them before they begin changing color.
  •  For maximum sweetness, wait until they turn their final color—red, orange, or yellow. 
  • Use scissors or a knife to cut the peppers off the plant, leaving a small piece of stem attached. 

This prevents damage to the plant and encourages it to produce more fruit throughout the growing season.

Harvest peppers by hand to promote further fruiting and prevent plant damage

7. Troubleshoot Common Growing Problems

Even in a greenhouse, sweet peppers can face challenges: 

  • Yellowing leaves often indicate overwatering or nutrient deficiencies, while flowers that fall off without forming fruit may suggest the temperature is too low or too high. 
  • Pests like aphids can still find their way in, so keep an eye on your plants and act quickly if you spot trouble. 
  • Introduce beneficial insects like ladybugs or adjust your greenhouse settings as needed. 

Regular observation is the best way to catch problems early and keep your pepper plants thriving.

Monitor your plants regularly to address issues like overwatering or pest damage.

Browse Our DIY Greenhouse Kits and Start Growing Sweet Peppers

With the right care and techniques, growing sweet peppers in your greenhouse can be easy and rewarding. 

From choosing the perfect variety to managing pests naturally and harvesting at peak ripeness, these tips will set you up for success. 

Looking to upgrade your greenhouse for even better results? Check out our DIY greenhouse kits to create the ideal environment for your sweet pepper plants!

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