Pepper seed moves fastest with the soil at 85°F (29°C). At that temperature a crop of Capsicum annuum breaks the surface in about eight days. Cool the soil to 59°F (15°C) and the same seed needs 25 days. Those figures come from J.F. Harrington's soil temperature work at UC Davis, which extension services still reprint sixty years on. Fruiting runs on a separate clock and splits hard by species: 50 days from transplant for a quick annuum, 115 or more for a superhot.

What soil temperature does to emergence

Harrington's table gives pepper a minimum of 60°F (16°C), an optimum of 85°F (29°C) and a maximum of 95°F (35°C). The curve between those points matters more than the endpoints.

Soil temperatureDays to emergence
59°F (15°C)25
68°F (20°C)12
77°F (25°C)8
86°F (30°C)8
95°F (35°C)9

Note the flat bottom. Anywhere from 77°F to 86°F buys the same eight days, so chasing the last degree gains nothing. Note also that the penalty for cold is brutal and not linear. Nine degrees below optimum costs four extra days. Another nine costs thirteen more. Measure the medium, not the air: a tray sitting on a cold bench often runs 10°F under the room.

Germination and fruiting by species

Harrington tested commercial C. annuum. Everything else below comes from The Chile Pepper Almanac, which sets a separate protocol per species and separates what it has tested from what it has estimated. The last column carries that distinction, because it matters more than the numbers do. Days to maturity count from transplant, not from sowing.

SpeciesOptimal soil tempDays to germinateDays to ripe fruitData status
C. annuum80 to 85°F (27 to 29°C)7 to 1450 to 85Documented.
C. baccatum78 to 86°F (26 to 30°C)8 to 1885 to 100Documented.
C. chinense82 to 90°F (28 to 32°C)10 to 3095 to 120Documented.
C. frutescens78 to 86°F (26 to 30°C)10 to 2585 to 100Documented.
C. pubescens65 to 78°F (18 to 26°C)14 to 35100 or moreDocumented.
C. annuum var. glabriusculum85 to 90°F (29 to 32°C)14 to 45100 to 150Documented. Wild chiltepin and tepin forms.
C. chacoense86 to 90°F (30 to 32°C)14 to 45No published figureGermination documented. Scarification required.
C. eximium84 to 88°F (29 to 31°C)14 to 35No published figureGermination documented. Hot-water pre-treatment works.
C. cardenasii84 to 88°F (29 to 31°C)14 to 35No published figureGermination documented. Scarify before treating.
C. praetermissum82 to 86°F (28 to 30°C)14 to 28No published figureGermination documented.
C. flexuosum80 to 86°F (27 to 30°C)14 to 35No published figureGermination documented.
C. rhomboideum75 to 82°F (24 to 28°C)21 to 45No published figureGermination documented. Non-pungent basal lineage.
C. galapagoense80 to 85°F (27 to 29°C)21 to 60No published figureGermination documented. Seed rarely available.
C. tovarii75 to 82°F (24 to 28°C)21 to 60No published figureGermination documented. Slowest of the group.
C. lanceolatum75 to 82°F (24 to 28°C)21 to 45No published figureGermination documented. Endangered, seed scarce.
C. parvifolium80 to 88°F (27 to 31°C) est.14 to 45 est.No published figureUnverified. Almanac estimate, wild protocol assumed.
C. minutiflorum80 to 88°F (27 to 31°C) est.14 to 45 est.No published figureUnverified. Almanac estimate, wild protocol assumed.
C. dimorphum75 to 82°F (24 to 28°C) est.21 to 60 est.No published figureUnverified. Almanac estimate, basal lineage.
C. scolnikianum75 to 82°F (24 to 28°C) est.14 to 45 est.No published figureUnverified. Synonym of C. geminifolium.
C. caballeroiNo published figureNo published figureNo published figureUnverified. Bolivian, unrecorded in cultivation.
C. eshbaughiiNo published figureNo published figureNo published figureUnverified. Bolivian, unrecorded in cultivation.
C. ceratocalyxNo published figureNo published figureNo published figureUnverified. Bolivian, unrecorded in cultivation.

No source anywhere publishes days to ripe fruit for a wild Capsicum species. Any table that gives you one has made it up.

Why does Capsicum pubescens germinate cooler than the rest?

Rocoto and its relatives come from Andean highlands, not lowland tropics. Their germination window sits at 65 to 78°F (18 to 26°C), with a ceiling near 80°F (27°C), so the heat mat that rescues a Habanero tray will stall a Rocoto tray. Growers who run one mat for everything usually blame the seed. The seed is fine. Split the trays, give pubescens its own corner at 70 to 75°F, and expect 14 to 35 days. Cold stratification does not apply here; a tropical highland species wants steady warmth, not a simulated winter.

How long from transplant to ripe fruit?

Count from transplant, since that is how seed catalogues quote days to maturity. Padrón and Shishito ripen around 60 days. Serrano and Jalapeño run 72 to 75. Cayenne and Poblano land near 75. Aji Amarillo takes about 90 and Habanero about 95. Ghost Pepper needs 105 and Carolina Reaper about 115. Those numbers assume days of 70 to 85°F (21 to 29°C). Cool weather adds two to three weeks, which is why a northern grower starts superhots in January for an August picking.

What about the rare wild species?

Read the status column before you plan a season around it. Nine wild species carry worked germination protocols: chacoense, eximium, cardenasii, praetermissum, flexuosum, rhomboideum, galapagoense, tovarii and lanceolatum. All of them want a hard seed coat dealt with first, by scarification or hot water, before any chemical treatment. For the treatment side, see the GA3 guide.

The rest sit in the estimate column for a reason. The Almanac marks parvifolium, minutiflorum, dimorphum and geminifolium as inferred from the general wild protocol rather than tested, and records "unknown" against caballeroi, eshbaughii and ceratocalyx. It also lists C. scolnikianum as a synonym of C. geminifolium rather than a species of its own, so the two names describe one plant. Treat a precise day count for any of these as a guess dressed up as data, including the estimates above.

Sources & Further Reading