Plastic as a Ground Cover

To use plastic or not to use plastic, that is the question. Many gardeners wonder if it is worth the time and effort to cover the soil surrounding their plants with plastic. All manufacturers of plastic are not the same. When doing research, pay attention to the colors offered, the composition, and which plants will reap the most benefit from plastic.

There are three colors of plastic groundcover: black, red and olive. Each color produces slightly different results in the growth of the plants they are surrounding. A recommended composition for plastic is embossed high-density polyethylene material which gives plastic the flexibility to stretch smoothly over the ground.

The black plastic boosts plant productivity because it blocks the sunlight, eliminating the growth of weeds. The red plastic not only eliminates the growth of weeds, it also reflects the sunlight and increases the photosynthesis of developing plants. The olive mulch is a hybrid plastic combining the advantages of black and clear plastic. It utilizes the black plastic advantage of deterring weeds and has the clear plastic advantage of warming the soil.

Plastic groundcover is used for weed control, higher soil temperatures and holding the moisture in the ground so the root systems do not dry out. The weeds are controlled by the elimination of sunlight. The soil temperatures increase between 3 to 6 degrees F at a 2- to 6-inch soil depth. The warmer the soil, the faster the root system grows, meaning the plant will mature and produce fruit/vegetables earlier in the season.

The plastic groundcover does hold the moisture in, but there is some evaporation through the hole where the plants grow. If it has been an unusually dry season, periodic watering is necessary.

Each color of plastic is best used with certain crops. The black plastic is most beneficial for vegetables, vine crops, small fruits such as strawberries and cut flowers. Red plastic works well for tomatoes, peppers and melons in particular, as well as strawberries and cut flowers. Olive mulch is most effective with transplants, small fruits and cut flowers.

Always work the soil before applying the plastic. The soil should be smooth so the plastic lies evenly and flat. The more contact the plastic has with the soil, the quicker the soil will warm. Before laying the plastic, moisten the soil. Stretch the plastic smoothly over the ground and tuck the edges in tightly with soil.