Mulches can conserve moisture, moderate soil temperatures, suppress weeds, prevent erosion and insulate root crops left in the ground over winter. Typically, you will want 2”-4” of mulch for best results, varying somewhat with the size of your plants, how much insulation you require and the coarseness of your mulching materials. Remember to regularly check the depth of your plant-based mulches as these will break down over time. Water-retaining mulches should start about 2” away from the stems of garden plants and 6” away from the trunks of trees in order to prevent rotting the base of your plants. Also, keep flammable mulches at least 5’ away from structures. Here are a few mulches to try:
Straw and hay. Good for use in the garden. These encourage a bacterially dominant soil which is excellent for healthy vegetables and garden fruits. Purchase seed-free to prevent introducing new grass seed to your beds!
Leaves. Very nourishing and enriching as it breaks down, but it is a good idea to run the lawnmower over them before you spread them or you could end up with a layer that water will not penetrate.
Bark and wood chips. A good choice for around trees and shrubs as they encourage a healthy fungal zone that helps with nutrient uptake in woody plants.
Gravel, pebbles and stone. These have thermal mass that will help warm soil in the spring and moderate overnight temperatures. Some growers recommend a ring of pea-sized gravel in the 6”-8” inches immediately surrounding tree trunks as it will not harbor pests or bacteria.
Plastic. Irrigation systems must be installed underneath as it is non-permeable (sprinklers will not work!), but it can do a great job of suppressing weed growth and conserving moisture and warmth. Certain plants prefer certain colors—for instance, use red for strawberries, silver for peppers and black for potatoes.
Note: You may want to avoid mulch initially when you are direct-seeding in the garden as it may inhibit germination and seedling growth, just as it does with weeds. A better alternative might be to cover your seeds with burlap or a floating row cover. These will also conserve moisture, allow water infiltration, prevent erosion and moderate soil temperatures, but will allow light to stimulate growth. You can then switch to a mulch when the plants are established.