Black plastic film can suppress weeds and warm soil for heat-loving transplants, but it is not a general soil improver. It blocks rainfall, contributes plastic waste, and may make the root zone too hot or too wet.
- Use purpose-made garden mulch film, not unknown construction plastic or reused chemical packaging.
- An adult should install it on moist, smooth soil after any needed compost or fertilizer has been incorporated.
- Put drip or soaker irrigation underneath before fastening the edges. Do not depend on rain pooling on top or save stagnant runoff for edible crops.
- Stretch it snugly so the film touches the soil and transfers heat. Anchor every edge so wind cannot turn it into litter.
- Cut only the planting holes needed. Adults should handle knives or scissors.
- Check soil moisture and temperature below the film; the surface can hide both drought and waterlogging.
- Remove all pieces at the end of the crop. Do not till ordinary polyethylene into the soil or leave fragments behind.
The temperature change is not one fixed number: colour, sunlight, soil contact, season, and weather all matter. Organic mulch, paper, or a reusable row cover may meet the goal with less waste.