Black plastic mulch for soil warming in spring

Black plastic mulch (also called black poly mulch) absorbs solar radiation and transfers heat to the soil, raising soil temperature by 5-8 degrees F compared to bare ground. This accelerates seed germination and root establishment for warm-season crops by 1-3 weeks. Lay the plastic over the bed 2-4 weeks before planting to pre-warm the soil. Cut X-shaped slits where each transplant will go and plant through the slits. The plastic also suppresses weeds and retains soil moisture by preventing evaporation. Standard black plastic mulch costs $10-20 for a 3x50-foot roll. Use drip irrigation underneath the plastic since overhead watering cannot penetrate it. In hot climates (zones 8+), switch to reflective silver or white plastic mulch in midsummer to prevent overheating soil. Infrared-transmitting (IRT) plastic mulch is a premium option ($20-30 per roll) that warms soil like black plastic but allows beneficial infrared radiation through while suppressing weeds. Remove plastic at end of season; it is not biodegradable. For a more sustainable approach, use biodegradable black mulch film that breaks down in 60-90 days, though it costs more and is less durable.