There are two kinds of mulches - organic and plastic. Organic mulches are loose materials such as wood chips, straw, flax shives or bark. These mulches have been used for years to control weeds and conserve moisture. They can be difficult to obtain in large quantities and application is often laborious. In most cases, soil temperature is cooler under these mulches.
Plastic mulches are sheets or rolls of plastic that are laid on the ground around the trees.
They effectively prevent weed germination and are normally easier to apply than organic mulches. Plastic mulches increase and maintain soil temperature. Some plastic mulches are designed to both retain water and allow excess water to evaporate. Mulches help seedlings grow by increasing the temperature of the soil and holding the heat during cool evenings. They can also protect plants from extreme hot and cold temperatures.