Pepper
Capsicum annuum
A heat-lover that's botanically a perennial but grown as an annual — start it early indoors, plant it into warm soil, and keep moisture even or pay in blossom-end rot.
At a glance
- Sun
- Full sun
- Water
- Moderate
- Soil pH
- 6–7
- Days to maturity
- 70–85
- from transplant to mature green (Clemson; UMD 70–80), plus 2–3 weeks more to ripen to full color
- Spacing
- 12–18 in
- Clemson 12 in, UMN 18 in, in rows ~3 ft apart
- Germination soil
- 80–90°F
Mature size: Plants can reach 3–4 ft tall; caging or staking keeps brittle, fruit-laden stems from snapping.
Hardiness
A very tender warm-season perennial grown as an annual in every US zone — frost injures the top growth, and even chilly nights set it back. In frost-free climates a plant can carry over, but US garden culture treats it as an annual.
Sun
Full sun — at least 6 hours of direct light a day; 8–10 hours preferred (UMD).
Water
About 1 inch a week by soaking at the base — avoid overhead sprinkling. Even moisture matters more than quantity.
Planting calendar
Timed to your own frost dates — look up yours by ZIP on the home page.
- Start indoors 6–10 weeks before your last spring frost. UMN says ~8 weeks; Clemson 6–8; Utah State and UMD allow 8–10 (slow cultivars to 12). Peppers are slower than tomatoes — start them first.
- Transplant — Set out only after all frost danger has passed, nights stay above 50°F, and the soil has reached about 60°F. During hardening off, bring plants in if nights drop below 55°F.
- Direct sow — Not practical in most of the US — the seedling stage is too slow and cold-sensitive. Start indoors and transplant.
Peppers are tomatoes' slower, more heat-demanding cousins — same family, same bed, same enemies, but a narrower comfort zone at both ends of the thermometer.
The fruit-set window
Pepper flowers abort when nights drop below 55°F or days push past 90°F (Utah State). Plants grow best around 70–85°F days and 60–70°F nights (Clemson). That window explains the classic mid-summer stall in hot climates — the plant is fine, it just stops setting until the heat breaks.
Blossom-end rot isn't just for tomatoes
The sunken dark patch on a pepper's bottom is the same calcium-uptake failure tomatoes get, brought on by uneven watering rather than poor soil. Keep moisture uniform — mulch helps — and it largely disappears.
Sunscald
Fruit that loses its leaf canopy in hot, dry weather bleaches and blisters on the sun side. Healthy foliage is the defense; in extreme heat, light afternoon shade earns its keep (UMD).
Warm soil first, then mulch
Black plastic mulch warms spring soil for this heat-lover (UMN); once summer arrives, any mulch's job flips to holding moisture steady and keeping weeds down.
Harvest with scissors
Cut the stem rather than pulling — pepper branches are brittle and snap easily (Clemson). Green bells are mature at full size; left another 2–3 weeks they ripen to red, yellow, or orange and sweeten considerably (Utah State counts 35–45 days from flower to full color).
Common pests
- Aphids
- Cutworms
- Flea beetles
- Tomato hornworm
- Thrips
- European corn borer
- Stink bugs
Common diseases
- Bacterial leaf spot
- Tomato spotted wilt virus
- Cucumber mosaic virus
- Anthracnose fruit rot
- Southern blight
- Root-knot nematodes
- Blossom-end rot (physiological)