Starting from Seed vs. Seedlings
A guide to starting jalapeño peppers from seed indoors, hardening off, and deciding between seeds and nursery transplants.
8-10 wks
Start before last frost
80-85°F
Ideal soil temp
7-14 days
Germination time
Quick Answer
Start jalapeño seeds indoors 8-10 weeks before your last frost date. Use a heat mat to keep soil at 80-85°F for best germination. Transplant outdoors after nighttime temperatures consistently stay above 55°F.
When to Start Seeds Indoors
Jalapeño seeds need warmth and time. Count back 8-10 weeks from your average last frost date to determine your start date. In most of the US, that means starting seeds between late January and mid-March. Use seed-starting trays with a dome to retain moisture and a heat mat to maintain soil temperature at 80-85°F. Jalapeño seeds are slow to germinate — expect 7-14 days with heat, or up to 4 weeks without.
Germination Tips
Plant seeds 1/4 inch deep in a sterile seed-starting mix. Keep the mix consistently moist but not waterlogged. Once seeds sprout, remove the dome and move them under strong grow lights (14-16 hours per day) or a sunny south-facing window. Thin to one seedling per cell once they develop their first set of true leaves.
Pro Tip
Hardening Off
About 7-10 days before transplanting, begin hardening off seedlings by placing them outside in a sheltered spot for 1-2 hours, gradually increasing time and sun exposure each day. This prevents transplant shock and sunscald. Avoid putting seedlings in direct wind or full sun on day one. By day 7-10, they should be spending the full day outside.
Common Mistake
Seeds vs. Nursery Transplants
Starting from seed gives you access to more varieties and costs less, but requires 8-10 weeks of indoor growing. Nursery transplants save time and are a good option if you missed your seed-starting window. If buying transplants, look for stocky plants with dark green leaves and no flowers yet. Avoid leggy or root-bound seedlings.