Pepper fruit set suffers when night temperatures stay above ~21C (70F); the same hot spell's high days compound it.
Promising · costly if ignored → warn
How it works
Warm nights above ~21C (70F) weaken pepper growth and, together with hot days, leave flowers poorly pollinated so they drop before setting fruit. Pepper carries a second heat driver this night threshold does not see - daytime highs above ~34C (94F) also abort the flowers - so this rule catches only the night half of a two-sided problem.
What to do about it
Wait it out - pepper sets fruit again once the nights cool. Shade cloth cools the day but not the night this rule fires on, so it will not fix hot-night drop; keep the plants watered and unstressed so they carry the flush that follows.
The evidence
Evidence: confirmed against 2 sources in the research-based literature.
the 2 sources
UMN Extension, 'Growing peppers', extension.umn.edu/vegetables/growing-peppers (fetched in-container 2026-09-03; read by the maintainer 2026-09-03): 'Dry soil, temperatures above 90F, or night temperatures below 60F or above 70F, can weaken plant growth'; 'When Minnesota has hot days and hot nights, pepper flowers can drop, leading to less fruit production.' 70 F is 21.1 C and this field is Celsius, so the stored 21 is that sentence rounded to the nearest degree, the same rounding tomato's night figure carries.
Univ. of Missouri Extension, 'Growing Sweet Peppers in Missouri', G6372, extension.missouri.edu/publications/g6372 (fetched in-container 2026-09-03; read by the maintainer 2026-09-03): 'Excessively high or low air temperatures (higher than 94 degrees F or lower than 50 degrees F) can reduce fruit set of peppers by causing flowers to drop from the plant.' Pepper's flower drop is driven by hot days as well as hot nights; a night threshold sees only the one half.
Plants this fires on
Change history
Every change to this rule is one commit. This is what the project's version history records — the date and the reason — not a summary of it.
- corpus: another rule here pepper hot-night fruit-set warning, verified; dispatch made data-driven (O135 follow-up)
Cite this page
Milpa Gardens. "Pepper fruit set suffers when night temperatures stay above ~21C (70F); the same hot spell's high days compound it." Evidence grade: Promising. https://milpa.garden/rules/pepper-fruit-set-suffers-when-night-temperatures/
A garden-planning corpus: every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.