When to start pepper seeds
Short answer: sow peppers indoors 8 to 10 weeks before you plan to plant them out, which is about 2 weeks after your average last frost. Start them in warm soil, because pepper seed is slow in the cold.
At a glance
- Start indoors
- 8–10 weeks before setting out (UNH); UMN says about 8 weeks
- Set out
- About 2 weeks after last frost (UNH), once night lows stay above 50°F (UMN)
- Germination temperature
- 70–75°F (Iowa State); UMN suggests 80–90°F on a heat mat until emergence
- Days to sprout
- 7–10 days (Iowa State); 25 days at 59°F soil, 8 days at 77°F (Harrington)
- Direct sow?
- No; grow from transplants
UNH = University of New Hampshire Extension; UMN = University of Minnesota Extension; Harrington = J. F. Harrington's germination data as published by Oregon State University Extension. Full links are under Sources below.
Your dates: peppers seed-starting calculator
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How many weeks before the last frost?
Peppers take longer from seed than tomatoes. University of New Hampshire Extension gives them 8 to 10 weeks from seed to transplant and says they are safe to set out 2 weeks after the last frost. With an average last frost of May 10, you would sow indoors March 15 to March 29 and set plants out May 24.
University of Minnesota Extension says about eight weeks, and points out that this is earlier than you would normally start tomatoes. If your tomatoes and peppers go out together, sow the peppers two weeks or so before the tomatoes.
Germination: give them real warmth
Pepper is one of the slowest common vegetables to germinate in cool conditions. Harrington's trials (published by Oregon State Extension) recorded about 25 days to emergence at 59°F, 12 days at 68°F and 8 days at 77°F or 86°F. Below 60°F, the minimum listed, germination was little or none.
Iowa State Extension lists 70–75°F for indoor germination, with seedlings in 7 to 10 days. UMN goes warmer, recommending a heat mat at 80°F to 90°F until seedlings emerge, then about 70°F soil. Remove any clear dome once seedlings appear, and watch moisture because heat mats dry the mix quickly.
Sow seeds a quarter inch deep in sterile, soilless seed-starting mix (UMN). Older seed germinates less reliably; UMN suggests sowing two or more seeds per cell when using older seed and snipping extras at soil level.
Growing on
- Thin or pot up after true leaves appear so seedlings stand 2 to 3 inches apart under bright overhead light.
- Peppers sometimes flower indoors. UMN suggests pinching off the flower buds until just before you set the plants out.
- Reduce watering when plants are 4 to 5 inches tall and 6 to 8 weeks old, as you start hardening them off.
Hardening off and transplanting
Move plants outside to a spot with wind protection and a couple of hours of sun, then give them more sun over a week or two. UMN advises bringing pepper seedlings indoors if night temperatures drop below 55°F during this period.
Transplant outdoors after nighttime lows are above 50°F. UMN notes that night temperatures below 60°F or above 70°F, dry soil, or days above 90°F can weaken growth, so a warm spot pays off. Space plants about 18 inches apart in rows 30 to 36 inches apart, and set them at the same depth they grew in the pot. Black plastic mulch warms the soil and helps peppers in cool climates.
Common mistakes
- Germinating in a cool room. At 59°F you could wait over three weeks. A heat mat cuts that to about a week.
- Starting them with the tomatoes. Peppers need the extra two weeks indoors.
- Setting out too early. Cold nights stall peppers. Waiting for 50°F nights usually gives faster growth overall.
- Burying the stem. Unlike tomatoes, peppers go in at the same depth they grew.
- Letting the mix dry on a heat mat. Check it daily.
Example schedules
The same timing rules applied to three different average last frost dates. Find your own date on the frost dates page, or check your zone planting calendar for typical ranges.
| Last frost | Start indoors | Plant out | Direct sow |
|---|---|---|---|
| Mar 15 | Jan 18–Feb 1 | Mar 29 | — |
| Apr 15 | Feb 18–Mar 4 | Apr 29 | — |
| May 15 | Mar 20–Apr 3 | May 29 | — |
Supplies
Optional. You can start seeds with very little gear; these are the items that make the steps above easier. Disclosure: some links on this site may be affiliate links; if you buy through them we may earn a commission at no extra cost to you. Learn more.
- Seedling heat mat with a thermostat: peppers germinate fastest at 80–90°F soil.
- Soil thermometer: to check the mix temperature rather than guessing.
- Pepper seed suited to your season length: UMN suggests smaller-fruited types for short, cool summers.
- Cell trays and 3–4 inch pots for potting up: peppers spend 8–10 weeks indoors.
Frequently asked questions
When should I start pepper seeds indoors?
About 8 to 10 weeks before you plan to plant them out (UNH). Since peppers go out about 2 weeks after the last frost, that is roughly 6 to 8 weeks before your last frost date.
Why are my pepper seeds not germinating?
Usually the soil is too cool. Harrington's data show about 25 days to emerge at 59°F and little or no germination below 60°F. UMN recommends 80–90°F on a heat mat.
Should I remove flowers from pepper seedlings?
UMN suggests pinching off flower buds that form indoors until just before the plants go into the garden.
How cold is too cold to plant peppers outside?
UMN says to transplant after night lows are above 50°F, and to bring hardening-off seedlings in if nights drop below 55°F.
Sources
- University of New Hampshire Extension — Growing Vegetables: When to Plant Your Vegetable Garden
- Oregon State University Extension — Soil temperature conditions for vegetable seed germination (J. F. Harrington data)
- Iowa State University Extension — Germination Requirements for Annuals and Vegetables
- University of Minnesota Extension — Growing peppers in home gardens
- University of Minnesota Extension — Starting seeds indoors
Dates in the calculator and example tables use the University of New Hampshire Extension timings. Average frost dates are not guarantees; check the forecast before setting out tender plants. Last reviewed 2026-10-23. Found an error? Tell us.