It is too early to plant in a cold weather greenhouse when temperatures are still fluctuating too much, or if the greenhouse is not yet adequately insulated to retain heat. If nighttime temperatures consistently drop near freezing or below, the risk of frost damage increases, even inside the greenhouse. Planting should wait until the greenhouse maintains a stable temperature above 40°F, as most crops require a minimum temperature for healthy root and leaf development.
It’s important to monitor both day and night temperatures and ensure the greenhouse is properly prepared with insulation, thermal mass, or supplemental heating before planting. Early planting without sufficient warmth can stunt growth, cause stress to seedlings, and may result in poor yields.
