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Vegetable Crop Calendars (A–C)Pepper Planting Calendar: Indoor Start to Transplant
Peppers reward the gardener who starts early and plants late. The seed goes in weeks before you would start tomatoes, and the transplants wait for warm nights.
Key points
- Start seed about eight weeks before your planned transplant date.
- Heat mat range of 80 to 90 degrees helps germination; 70 degrees soil is a good target.
- Transplant when nights stay above about 50 degrees, not just after the last frost.
- Harden off gradually over one to two weeks.
When should you start pepper seeds indoors?
University of Minnesota Extension suggests starting seed about eight weeks before setting plants outdoors, which is earlier than you would normally start tomatoes. Peppers grow slowly as seedlings, so a late start leaves you with small plants at transplant time.
To get your date, first pick your transplant date from your frost date and night temperatures, then count back eight weeks. For example, if you plan to transplant in late May, you would sow in late March.
Label every tray with variety and sowing date, since peppers vary in speed and some hot types are slower than sweet ones.
How warm should the soil be for germination?
Minnesota's guidance is a soil temperature around 70 degrees as ideal for germination, with a heat mat holding the flat at 80 to 90 degrees until seedlings emerge. Warm is better than cool.
Watch moisture, since mats dry the mix faster. Use a sterile, soilless seed-starting mix and plant seed about a quarter inch deep. Once seedlings are up, bring them under bright light and keep the temperature gentler.
Light is as important as warmth. A sunny window is often too weak, which makes pale, leggy seedlings. Use bright lights placed close to the plants and raise them as seedlings grow.
When can pepper transplants go outside?
The same Minnesota source says to transplant once nighttime lows are above 50 degrees, and to bring plants in if nights fall below about 55 degrees while hardening off. It also notes that nights below 60 or above 70 can weaken plant growth.
Frost date alone is not enough. A pepper can survive a mild night that still sets it back for weeks. Look at the forecast lows, not just the calendar.
For example, if forecasts show lows in the mid-50s for several nights, wait. Planting a week later into warmer weather often beats a week of cold stress.
How do you harden off pepper seedlings?
Minnesota recommends starting in a wind-protected spot with a couple of hours of sun and increasing exposure gradually over one to two weeks. Reducing water when plants are about four to five inches tall helps toughen them.
Plant in late afternoon or on a cloudy, calm day to limit shock. Water in, and keep a row cover or cloche ready in case a cold night shows up unexpectedly.
Potting up to larger containers before transplant gives roots room, but avoid letting plants become rootbound or flower heavily in the tray; pinch early flowers so plants put energy into growth.
Why do transplants stall after planting?
Cold soil and cold nights are the leading causes, followed by rootbound plants and skipped hardening off. Compare the Minnesota numbers with your own state's pepper guide, since West Virginia University Extension and other states publish their own versions.
A stalled pepper rarely recovers fully. If a cold snap hits, cover plants rather than hoping, and avoid heavy feeding to push growth; follow your soil test.
Mulch can help once soil is warm, but laying plastic or mulch too early can hold cold in the ground, so wait for settled weather.
What about pests, disease and heat?
Peppers can face insect and disease problems that vary by region. Contact your county extension office for identification and current recommendations, and read any product label completely before use, including the pre-harvest interval.
In very hot spells, flowers may drop. That is a weather response, not a disease. Consistent water and a little afternoon shade in extreme heat can help.
Pollinators help many pepper types set fruit, so protect them by never applying products to open blossoms. Pre-harvest intervals on labels apply to peppers just as to any food crop.
What does a pepper timeline look like from seed to harvest?
Pulling the Minnesota numbers together gives a repeatable timeline you can slide to fit your own spring.
Here is the order of operations, counted back from your transplant date:
- About eight weeks before transplant: sow in a sterile mix on a heat mat.
- After emergence: move under bright light and keep the flat evenly moist.
- About two weeks before transplant: begin hardening off in a sheltered spot.
- Transplant day: nights above 50 degrees, late afternoon or cloudy weather.
- After planting: keep soil evenly moist, and have row covers ready for surprise cold.
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.