Bottomheat

Bottomheat, or bottom heat, refers to heat delivered primarily from the lower surface or element of a heating system. In horticulture and plant propagation, bottom heat is used to warm the root zone and soil to improve germination and early growth. It is commonly provided by electric seedling heat mats placed under trays, bench heating, or radiant-floor and cable-based soil heating in greenhouses. Maintained temperatures for many vegetables and herbs typically range from about 18 to 25°C in the root zone, though species-specific needs vary. Higher temperatures can speed germination but increase risks of root damage, damping-off, or uneven moisture. Bottom heat is often used with humidity control, such as propagation domes, to sustain high humidity and uniform warmth, reducing energy consumption compared with air heating alone. In cuttings propagation, warm soil promotes faster root formation and establishment.

In cooking, bottom heat describes heat energy delivered from the oven floor or lower heating element. It is used to promote a strong crust on breads and pizzas or to cook dishes more evenly from the base. Bottom heat can be used alone or with top heat; excessive bottom heat without adequate air circulation may burn the base while leaving the top undercooked. Many ovens offer adjustable bottom and top elements to suit different recipes.

Bottom heat strategies require consideration of the specific plant or recipe, moisture management, and safety to avoid overheating or burning.