Weed Barrier Fabric and Pins
Weed barrier fabric is a woven, polypropylene fabric. Used to enhance survival and growth on tree and shrub plantings, it allows water to penetrate, but does not allow weeds to grow through it, eliminating much of the labor involved in establishing seed-lings. Kansas Forest Service provides the fabric in units of 25 pieces of 4 by 4 feet fabric and 250, 10-inch wire pins to secure the fabric to the ground.
The fabric is guaranteed for five years against deterioration from sun damage. The first sign of deterioration is white to gray spots about 3 to 4 inches in diameter. The next phase is separation of ribbons, usually length-wise on the fabric. Finally it becomes a cigar-ash like material and disappears.
The fabric is very effective at conserving soil moisture, but it does not generate water. If the soil is dry when the seedlings are planted, they should be watered thoroughly. The fabric sheds water until the sun breaks down the silicone used to enhance the weaving process. After about 3 to 4 weeks of exposure to the sun, it allows penetration of 9 gallons of water per square foot per minute.
It is best to till the planting spot to kill existing vegetation and loosen the soil for rapid seedling root development. Plant the seedling and water it thoroughly to settle the soil around the roots and to ensure that there is adequate soil moisture. In all but exceptionally dry years, no supplemental watering is needed after the initial watering at the time of planting.
Pull the seedling through the center opening. Place pins in the four corners and the center of the fabric. The 10-inch pins tend to work out of the soil until they are pitted from soil moisture. They may have to be shoved back into the soil occasionally for a couple of weeks, then they will hold well on loam or clay soils. On lighter soils, a shovel of soil may have to be placed on the corners to secure the fabric. If weeds grow through the seedling hole, pull them out before they become well established.
Weed barrier fabric should not be considered a "plant them and ignore them" practice. Regular inspections are needed to check for such problems as insects, rodents building homes under the fabric, weeds growing through the planting hole, wind lifting the fabric, bark injury due to rubbing fabric, and need of supplemental watering.
Caution: Fast growing plants can fill the center hole before the fabric deteriorates, causing the fabric to girdle the plants. This may result in the death of the tree or shrub. The center hole may have to be enlarged as the plant develops to prevent damage.
For more information please read the full description of Weed Barrier Fabric here.