Sweet or hot
| Group | Examples | Scoville heat units (Penn State) |
|---|---|---|
| Sweet | Bell, banana, pimento, sweet cherry (Clemson); Italian frying (UMD); Cubanelle | Bell 0; pimiento 0–500; Cubanelle 500–1,000 |
| Hot, lower range | Poblano/ancho; New Mexican ('Anaheim', 'Hatch'), from no heat in paprika types to hot (NMSU); jalapeño | Poblano 1,000–2,500; jalapeño 2,500–10,000 (Clemson: 2,500–8,000) |
| Hot, middle range | Serrano, cayenne, tabasco | Serrano 10,000–25,000; tabasco and cayenne 25,000–50,000 |
| Hot, top range | Habanero, Scotch bonnet, ghost pepper, Carolina Reaper | Habanero 100,000–350,000; Carolina Reaper 1.5–2.5 million |
Clemson and UMD class jalapeño, serrano, cayenne, habanero and tabasco as hot. Bells, jalapeños and cayenne are all Capsicum annuum; habanero is C. chinense and Tabasco C. frutescens (Iowa State). Planting chiles beside sweet peppers will not make the sweet ones hot (UMD); crossing only matters for saved seed, which UMD says needs insect screening or 500 feet of isolation.
Heat comes from capsaicinoids made near the placenta, not in the seeds (NMSU), and rises as fruit ripens (Penn State, UNH). Heat and drought stress raise pungency only within a variety's range; for predictable heat Penn State suggests moderately rich soil and even watering. Hot peppers tolerate warm weather better than bells (Iowa State).
Timing: start early, plant late
| Step | Figures given |
|---|---|
| Start seed indoors | About 8 weeks before the last frost, a couple of weeks before tomatoes (UNH Infoline); 8–10 weeks from seed to transplant (UNH fact sheet); 8–10 weeks before the frost-free date, about 12 for some cultivars (UMD); 6–8 weeks before planting out (Clemson, Iowa State, NMSU, Colorado State) |
| Germination | Potting mix at 85–90°F, for example on a heat mat (UNH Infoline); 10–20 days to emerge, 80°F optimum (Colorado State) |
| Earliest transplant | 2 weeks after the last frost (UNH fact sheet); 2+ weeks, once days stay above 55°F (Colorado State); once nights stay above 50°F (UNH Infoline); mid-May in central Iowa (Iowa State) |
| Soil temperature | At least 60°F, measured 4 in deep at 8 a.m. (Colorado State); below 65°F plants "just sit there" (UMD) |
| Latest planting | About June 20 in Iowa (Iowa State); Clemson's South Carolina windows run May 1–June 30 in the Piedmont and April 1–May 15 plus July 10–August 10 on the Coastal Plain |
- Find your last frost date (frost dates explained); the planting calendar applies UNH's offsets.
- Check soil 4 inches deep in the morning; wait for 60–65°F. Black plastic mulch warms it (UNH, NMSU).
- Transplant in the early evening and water immediately (NMSU).
- Guard against cold: a week of days below 55°F may stunt the crop (Colorado State); floating row covers help young plants (NMSU).
Spacing and sun
| Source | In the row | Between rows or layout |
|---|---|---|
| Clemson | 12 in (pimento 18–24 in) | 3 ft (pimento 42 in) |
| NMSU | 8–14 in | Rows 24–30 in wide |
| Iowa State | 18 in | 24–30 in; or staggered double rows 12–18 in apart, bands 30–36 in apart |
| UMD | 12–24 in | 30–36 in; or staggered double rows in 2-ft-wide beds |
| Colorado State | 15–18 in | — |
In a raised bed without aisles, use the in-row figure each way, roughly 12–18 inches; compare square foot gardening spacing. Give peppers at least six hours of direct sun (Iowa State, UW–Madison); UMD prefers 8–10.
Peppers in containers
- 1. Full sun: at least 6 hours (UW–Madison, Iowa State); 8–10 preferred (UMD)
- 2. Light-colored pot, at least 5 gal (UMD, UW–Madison, N.C. A&T); dark pots can overheat roots (UMD)
- 3. Depth 12–16 in for 8–10 gal (UMD) or 12–18 in (UW–Madison)
- 4. Filled completely with potting mix, no gravel layer (UW–Madison, UMD)
- 5. Drainage holes; pot raised on feet, saucer emptied (UMD)
- 6. Cage set at planting; stems are brittle (UMD, N.C. A&T)
- 7. Even moisture; daily water once plants are large and fruiting (UW–Madison)
- Size: at least 5 gallons (UMD pepper page, N.C. A&T; UW–Madison adds 12–18 in deep). UMD's container scale gives one full-size pepper 8–10 gallons, 12–16 in deep, and dwarf peppers 4–6 gallons, 8–12 in deep. Compare container sizes for vegetables.
- Pot: light-colored plastic; dark containers can get hot enough to injure roots (UMD, N.C. A&T). Drainage holes are essential; UMD says a gravel layer does not improve drainage and may raise the water table.
- Mix: a light, well-drained commercial mix, filled to the top (UW–Madison); N.C. A&T warns that mixes high in peat moss compact.
- Water: lightly while plants are small, then daily as they grow, temperatures rise and fruit forms (UW–Madison); keep the mix moist but not soggy (N.C. A&T).
- Feed: the mix's starter fertilizer lasts about two weeks; then N.C. A&T feeds weekly with a water-soluble balanced fertilizer such as 20-20-20 until flowering and a higher-potassium one after.
- Support: set a wire cage early to avoid damaging roots (N.C. A&T).
Feeding and watering in beds
- Test first. Clemson, Iowa State and NMSU base fertilizer on a soil test. Without one, Iowa State works 2–3 lb of 5-10-5 per 100 sq ft into the soil before planting.
- Side-dress. Clemson applies calcium nitrate at ½ lb per 100 sq ft or 30 ft of row, 3–4 weeks after planting and again 3–4 weeks later, 4–6 in from the plants. NMSU side-dresses one week after flowering begins; UMD after the first fruits set.
- Go easy on nitrogen. Too much gives leafy plants with few fruit (Clemson, NMSU).
- Water evenly. About 1 inch a week (Iowa State), wetting the soil at least 6 in deep, most of all during fruit set (Clemson). NMSU links overwatering to Phytophthora root rot. Straw or leaf mulch keeps soil cooler in summer (UMD, NMSU).
- Support and pinch. UMD cages the brittle stems and pinches out early flowers and small fruits for stronger plants.
Harvest
- Days: 70–85 from transplanting (Clemson, UMD) or 100–120 from seed (Clemson). Bells reach mature green in 70–80 days and need 2–3 more weeks to color; habaneros take 90–120 (UMD).
- Green or colored: pick sweet peppers full size and firm. Colored fruit is sweeter and higher in vitamins (Iowa State, UMD) and does not ripen further once picked (UMD).
- Cut, don't pull: the stems are brittle (Clemson, UMD, N.C. A&T, UNH). Wear gloves for hot peppers (UNH, UMD, Iowa State).
- Before frost: pull whole plants and hang them in a warm place to ripen (UMD).
- Storage: 45–50°F for 2–3 weeks (Clemson, UMD), or up to 3 weeks (Iowa State).
Common problems
| Problem | What to look for | Cause and extension guidance |
|---|---|---|
| Blossom drop | Flowers fall without setting fruit | Nights below 60°F or days above 85°F (Iowa State; NMSU gives 60°F and 90°F); dry soil (UMD, NMSU). UMD suggests late-afternoon shade when evenings stay above 75°F |
| Blossom-end rot | Water-soaked spot at the blossom end turning brown and leathery (Iowa State); most often on long fruits (UMD) | Low calcium in the fruit, worsened by uneven moisture, high nitrogen and root pruning (Iowa State); can occur even with enough soil calcium if watering is interrupted (Clemson). UMD: pH 6.3–6.8, about ¼ cup gypsum per planting hole, calcium chloride sprays only temporary |
| Sunscald | Soft, light-colored patch on the sun side that turns white and papery (Iowa State) | Fruit exposed after leaves are lost to disease or insects (UMD). Keep leaf cover: control leaf diseases, fertilize lightly, use staggered double rows (Iowa State); remove damaged fruit (UMD) |
| Bacterial leaf spot | Small yellow-green, water-soaked leaf spots that turn brown and leave holes (Iowa State) | Spread by rain and overhead watering in warm, humid weather (Iowa State); among the most troublesome pepper diseases (Clemson) |
| Aphids, caterpillars | Insects on young growth; chewed fruit | Hand-pick caterpillars (Clemson); aphids by hand or insecticidal soap (N.C. A&T) |
For prevention, Clemson recommends disease-free transplants, keeping tobacco products away (tobacco mosaic virus), and growing peppers, tomatoes, eggplant or potatoes in one spot no more than once every three years; see the tomatoes crop page.
This page gives no pesticide rates. Clemson lists B.t. or spinosad for caterpillars in large gardens. If you use any product, follow the label exactly and check your state extension service's current guidance.
Where sources disagree
| Question | Figures given |
|---|---|
| Soil pH | 6.0–6.5 (Clemson); 6.5–7 (UNH); 6.3–6.8 (UMD blossom-end rot page); 7.0–8.5 for New Mexico soils (NMSU) |
| Yield per 10-ft row | 15–20 lb (Iowa State); 2–8 lb (UMD) |
| Container for one plant | 5 gal (UW–Madison, UMD pepper page, N.C. A&T) vs 8–10 gal (UMD container scale) |
Small-space checklist
- Six or more hours of direct sun, eight to ten if possible.
- Seed started 8–10 weeks before the transplant date, in warm mix.
- Transplanted about two weeks after the last frost, once soil reaches 60–65°F.
- About 12–18 in per plant in a bed, or one plant per light-colored 5- to 10-gallon pot with drainage.
- Cage in place on planting day.
- Even moisture; daily checks for pots in summer.
- Fruit cut, not pulled: colored is sweeter, riper is hotter.
Sources
- Clemson Cooperative Extension Home & Garden Information Center — Pepper (HGIC 1316, updated 2023)
- University of Maryland Extension — Growing Peppers in a Home Garden (updated 2024)
- Iowa State University Extension Yard and Garden — Growing Peppers in the Home Garden
- New Mexico State University — Growing Chile Peppers in New Mexico Gardens (Guide H-240, revised 2019)
- University of New Hampshire Extension — What is the best way to start growing my own hot peppers? (2019)
- University of New Hampshire Extension — Growing Vegetables: When to Plant Your Vegetable Garden (fact sheet)
- Colorado State University Extension — Vegetable Planting Guide (CMG GardenNotes #720, reviewed 2024)
- Penn State Extension — Growing Hot Peppers: Can You Make Them Hotter? (updated 2024)
- N.C. A&T State University Cooperative Extension — Growing Fruiting Vegetables in Containers: Tomato, Pepper and Eggplant
- University of Maryland Extension — Types of Containers for Growing Vegetables
- University of Wisconsin–Madison Extension — Growing Vegetables in Containers
- University of Maryland Extension — Blossom End Rot on Vegetables
- University of Maryland Extension — Sunscald of Vegetables (updated 2023)
All sources were opened and checked in October 2026. Rules and figures change; confirm with the original before acting.