When to Plant Peppers in Westminster, CO
Published: April 21, 2026
Pepper Planting Dates for Westminster, CO
| Start seeds indoors | February 2–9 |
| Last frost (average) | March 30 |
| Transplant outdoors | April 13–23 |
| Minimum soil temperature | 65°F |
| Expect first harvest | June 12 – July 12 |
| First fall frost (average) | November 1 |
Best Pepper Varieties for Westminster, CO
For Zone 6a Westminster, the best-performing pepper varieties are California Wonder, Keystone Giant, and Banana — all widely adapted, disease-resistant varieties proven across the transition zone. Poblano is a good alternative where disease resistance matters most, especially in humid summers. These varieties are typically stocked by local nurseries and are the safest bets for gardeners new to pepper in Westminster.
Growing Peppers in Westminster
Westminster sits in Zone 6a, with an average last frost of March 30 and first fall frost around November 1 — giving a 216-day frost-free growing season. Warm-season crops like pepper need soil at 65°F or above before transplanting; Westminster's frost calendar puts that window clearly in the late-spring to early-fall range.
Westminster's moderate climate supports pepper on the standard transplant calendar with minimal special accommodation. Succession planting — sowing fresh seeds or setting new transplants every 2–3 weeks through spring — stretches the harvest window and gives you a backup crop if pests hit the first planting.
Westminster's well-draining loam soils are among the best for pepper growing — focus on annual organic matter additions (2 to 3 inches of compost) and consistent moisture during drier months. Water pepper at 1 inches per week; loam holds moisture evenly without the drought-crack cycle of heavy clay or the rapid-drain losses of pure sand.
Pepper Calendar for Westminster
| Month | Task |
|---|---|
| February | Start seeds indoors under grow lights |
| March | Last frost — harden off seedlings outdoors |
| April | Transplant outdoors into warm soil |
| June | Expect first harvest window to open |
| November | First fall frost — harvest remaining, end of outdoor season |
Pepper Tips for Westminster Gardeners
- •Start indoors 8 full weeks before last frost — peppers are the slowest vegetable to establish from seed.
- •Nighttime temps must stay consistently above 55°F before transplanting — cold nights halt growth.
- •Succession plant pepper in Westminster every 2–3 weeks through spring to extend the harvest window into summer.
Common Pepper Pests in Westminster
- •Aphids — peaks July in Zone 6a (active May–September); clusters on leaf undersides; blast with a strong water spray or apply neem oil.
- •Pepper Weevil — peaks July in Zone 6a (active May–September); small dark weevil that bores into fruit; destroy infested fruit immediately and rotate crops.
- •Bacterial Spot — peaks July in Zone 6a (active May–September); small dark spots on leaves and fruit; copper spray as a preventative.
Check plants every 2–3 days during peak season — early intervention prevents most infestations from becoming serious.
What to Plant with Peppers in Westminster
In Westminster's moderate climate, Basil and Tomato are the most beneficial plants to grow alongside pepper. Basil repels whiteflies, aphids, and spider mites, and is planted at the same time as its partners. Keep pepper away from Fennel — it releases root chemicals that inhibit growth of most neighbors.
Frequently Asked Questions
When should I plant pepper in Westminster, CO?
In Westminster (Zone 6a), start pepper seeds indoors around February 2–9 and transplant outdoors around April 13–23. The city's average last frost of March 30 is the anchor date — count 8 weeks back for seed starting and 2 weeks forward for transplanting.
What zone is Westminster, CO for pepper growing?
Westminster is USDA Zone 6a. For pepper, this means a frost-free growing season of roughly 31 weeks running from March 30 to November 1. This is a comfortable window for warm-season crops like pepper — standard varieties work well.
When is pepper harvest season in Westminster?
Expect the first pepper harvest in Westminster around June 12, with harvest continuing through July 12. This is based on 60–90 days from transplant or direct sow.
How long does it take to grow pepper in Westminster, CO?
From transplant or direct sow to first harvest, pepper takes 60–90 days in Westminster's climate. Based on a typical planting date of April 13–23, expect your first harvest around June 12. Westminster's Zone 6a transition-zone climate produces maturity times right in the middle of the stated range.
What soil does pepper need in Westminster?
Westminster's loam soil is near-ideal for pepper. Work in 2–3 inches of compost before planting to boost organic matter and nutrient content. Minimal amendment is needed beyond that — loam holds moisture evenly without the drought-crack cycle of clay or the nutrient-loss issues of sandy soil.