Peppers

Peppers - sweet and hot alike - are slower and fussier to get started than tomatoes, but far more forgiving once they're actually in the ground and the weather has warmed up. The whole genus wants heat more than almost anything else it needs: cool soil and cool nights don't kill a pepper transplant outright the way frost does, but they stall it for weeks in a way the plant often never fully makes up over the rest of the season.

Why Peppers Sulk in Cool Soil

Pepper seed germinates slowly and unevenly below about 70degF, which is why starting seed on a heat mat indoors reliably beats a windowsill start - an unheated windowsill germination can take three weeks where a heated one takes one. The same heat-sensitivity carries through to transplanting: soil below the low 60s doesn't kill a pepper seedling, but root growth all but stops, and a stalled pepper transplant frequently gets outpaced by one planted two weeks later into genuinely warm soil. Waiting for real warmth, not just the last-frost date, is the single most useful timing habit for peppers.

Blossom Drop in Extreme Weather

Peppers are also unusually sensitive to temperature extremes at flowering: sustained daytime heat above the low 90s, especially combined with high humidity or hot nights that don't cool below the mid-70s, causes flowers to drop before setting fruit, and a plant can sit and flower without producing for weeks during a summer heat wave for this reason alone. This isn't a disease or a nutrient problem, and gardeners who respond by fertilizing heavily during a blossom-drop stretch usually just push more leaf growth instead - the plant typically resumes setting fruit on its own once temperatures moderate.

Companions: A Different Mix Than Tomatoes, for Different Reasons

Basil and onions both work the same pest-masking logic here as they do with tomatoes - a strong-scented neighbor makes the pepper plant a somewhat harder target for pests hunting by smell - though the specific pests differ (pepper maggot and aphids more than the tomato hornworm). Marigold's benefit is the same documented root-knot-nematode suppression it offers tomatoes, useful in soil with a known nematode history. Carrots' looser, deeper root system avoids competing with a pepper's comparatively shallow feeder roots, the same root-depth reasoning that applies to tomatoes but worth restating because it's genuinely a separate, correct fact about pepper roots specifically. Bush beans contribute real nitrogen via root-nodule fixation, which peppers - moderate-to-heavy feeders - can use. Okra is a Southern-garden classic pairing worth explaining on its own terms: in genuinely hot climates, tall okra planted on the pepper bed's south side can throw enough afternoon shade to reduce blossom drop during the worst heat, a practical microclimate benefit rather than a pest or nutrient effect.

Antagonists: Fennel and the Weaker Kohlrabi Case

Fennel carries the same real, documented allelopathic suppression against peppers that it carries against most garden neighbors, and is worth keeping in an isolated bed of its own regardless of what else you're growing near it. Kohlrabi is listed as an antagonist in some garden references on the reasoning that both are heavy feeders competing for the same soil nutrients when crowded, but this is a much thinner case than the fennel relationship - it's plausible nutrient competition rather than anything specifically documented for this pair, so we rate it as traditional lore rather than confirmed.

Hardening Off and Staking

Pepper transplants benefit from the same 7-10 day hardening-off process as tomatoes, gradually introducing them to direct sun and outdoor wind before a permanent move outside - skipping this step commonly causes sunscald on the leaves even on an otherwise healthy transplant. Taller pepper varieties and especially heavily-loaded plants can benefit from a light stake or cage once fruit sets, since a full load of peppers on a single main stem can snap it in wind or heavy rain, though this matters far less for peppers than for indeterminate tomatoes.