Pine straw isn't actually straw, but rather shed pine tree needles. Most home gardeners lay pine straw mulch because its uniform needles give gardens a neater look than other, more irregular organic mulches. But all mulch essentially provides the same service. It helps the soil maintain a more consistent temperature, conserves moisture, nourishes the soil and prevents weed growth. Generally, pine straw mulch comes in three types: slash, loblolly and longleaf. They differ slightly in length and appearance, but they are all laid in the same way.
Spread a 2- to 3-inch layer of pine straw around garden plants with gloved hands. The mulch may cover the entire planting area, but should at least cover rows where plants are growing. Keep the mulch from directly touching the base of your plants (a 1- to 2-inch berth should be sufficient). Well-drained soil can tolerate up to 3 inches of pine straw mulch, but poorly drained soil should have a thinner layer--no more than 2 inches.
Spread a 3- to 4-inch layer of pine straw mulch around trees and shrubs with a rake. Keep the pine straw mulch between 8 and 12 inches from the base of the plant and spread out about 1 1/2 times the area of the tree or shrub's drip line.
Water the pine straw mulch to help it settle after it is spread.
Lay more pine straw each year as the mulch settles and decomposes to keep the mulch at the same level.