Growing Serrano Peppers: A Complete Profile
By Growing Home Greens Team · September 30, 2026
Serranos are slim, glossy chiles usually eaten fresh and green in salsa and pico de gallo. They are noticeably hotter than a jalapeño.
Heat and harvest
Bonnie Plants rates serrano at 15,000 to 30,000 Scoville units, with fruit 3 to 4 inches long. Bonnie lists at least 80 days after planting and Burpee 75 days. Burpee notes they can be picked green and mild or left to turn red for full heat. Johnny’s rates its Altiplano hybrid “very hot.”
A productive, mid-sized plant
Burpee gives 24 inches and Bonnie lists serrano as a medium plant, 24 to 48 inches. Plants set a lot of small fruit, so a single plant goes a long way.
Start seed indoors about eight weeks before your last frost. One plant per square foot in the Garden Designer. Wear gloves when cutting a large batch. The Bell Pepper profile covers shared care, and the companion guide lists neighbors.
Hot nights and dropped flowers
Pepper flowers fall off without setting fruit when nights stay above about 75°F, per the University of Delaware’s Weekly Crop Update. In zones 9 and up, expect a midsummer gap in fruiting; our zone pages flag it.
Growing it next to other peppers
Different pepper varieties cross-pollinate easily, hot ones included. NC State Extension notes that when hot and sweet peppers cross, the heat shows up in later generations grown from saved seed, and suggests keeping varieties 20 to 30 feet apart if you plan to save your own. Baker Creek, which grows seed for sale, isolates varieties by at least 500 feet. If you buy fresh seed each year, you can plant sweet and hot peppers side by side.
Sources: Bonnie Plants, Serrano; Burpee, Serrano; Johnny’s, Altiplano; NC State Extension, Saving Your Own Seed; University of Delaware Weekly Crop Update.
Companion planting guide for Serrano Pepper · Find your planting dates
Typically viable in USDA zones 3-11. Not sure your zone? Look it up by ZIP code.
Mature height: 2-3 ft
Method: Start indoors: Start indoors from seed, then transplant outside. It needs a head start most zones can't give it by direct-sowing alone.
When to plant serrano pepper, by zone
Every zone serrano pepper grows in. Pick your zone in the header and it will be highlighted here. Each zone links to its full page.
| Zone | Start indoors | Sow or plant out | Harvest |
|---|---|---|---|
| 3a & 3b | Apr 4–Apr 11 | Jun 13–Jun 20 | Aug 30–Sep 6 |
| 4a & 4b | Mar 20–Mar 27 | May 29–Jun 5 | Aug 15–Aug 22 |
| 5a & 5b | Mar 15–Mar 22 | May 24–May 31 | Aug 10–Aug 17 |
| 6a & 6b | Feb 28–Mar 7 | May 9–May 16 | Jul 26–Aug 2 |
| 7a & 7b | Feb 13–Feb 20 | Apr 24–May 1 | Jul 11–Jul 18 |
| 8a & 8b | Jan 28–Feb 4 | Apr 8–Apr 15 | Jun 25–Jul 2 |
| 9a & 9b | Dec 21–Dec 28 | Mar 1–Mar 8 | May 18–May 25 |
| 10a & 10bSpring window | Dec–Feb | Feb–Apr | ~78 days after transplanting |
| Summer window | May–Jul | Jul–Sep | ~78 days after transplanting |
| 11a & 11bSummer window | Jun–Dec | Aug–Feb | ~78 days after transplanting |
Harvest dates are about 78 days after the sow or plant-out date, not after starting seeds indoors.
See exact start-indoors, direct-sow, and harvest dates for your zone →
How many Serrano Pepper plants fit per square foot?
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 2-3 ft.
Soil & water: pH 6-6.5. Needs well-drained soil. Amend with lime if soil pH falls below 6.
Good companions for serrano pepper
- Basil: Reputed to repel aphids and improve pepper growth nearby, but a controlled garden trial testing this same claim on a related crop found no pest-reduction benefit from basil, and found higher pest counts on the basil-companioned plants. Treat this pairing as unproven, not as a working pest deterrent.
- Onion: Reputed to deter many common pepper pests, though this specific pairing hasn't been tested the way onion/carrot pest-masking has. Treat it as garden tradition.
Full companion guide, including what to keep away from serrano pepper →
Where to buy serrano pepper seeds
Botanical Interests · Burpee (serrano pepper seeds)
As an Amazon Associate we earn from qualifying purchases. Some links on this page also go to other retailers we may earn a commission from as an affiliate, at no extra cost to you. We only recommend products with a clear consensus of positive, independent reviews, or ones we bought and use ourselves. Each item on our gear page says which.
See it growing
Search YouTube for "growing serrano pepper" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
Pin this for later
Growing Serrano Pepper: A slim, crisp chile several times hotter than a jalapeño, for salsa and pico de gallo.
Save to Pinterest