Maintain Proper Temperature for Germination and Growth

Keep soil temperature at 70-80°F (21-27°C) during germination using a seedling heat mat placed under the tray. Once seedlings emerge, reduce the ambient temperature to 65-70°F (18-21°C) for sturdy growth. Remove the heat mat after most seeds have sprouted.

Why It Works

Warm soil accelerates the metabolic processes that trigger seed germination. Heat-loving crops like peppers and tomatoes germinate significantly faster and more uniformly on a heat mat. Slightly cooler air temperatures after emergence prevent rapid, weak stem elongation.

Tips

• Use a soil thermometer rather than relying on room temperature, which can differ by several degrees
• Avoid placing trays on cold windowsills or near drafts that create uneven temperatures
• Most cool-season crops (lettuce, brassicas) germinate well at 60-70°F and do not need a heat mat