"PermaTill Vole Block Recommended by Garden Guru Andre Viette! PermaTill is made of Expanded Slate produced by firing a special slate (compressed volcanic ejecta) through a rotary kiln at temperatures in excess of 2000 F. This creates a durable, lighter, non-toxic, porous granular that is sterile and environmentally inert. As such, it will not degrade, compress, blow, or float away, therefore the repellent does not need to be re-applied year after year. The Stalite has low absorption, so the pores act as tiny reservoirs storing moisture and any available soluble nutrients which are easily released and available for the roots. Great for aerating compacted clay soil. 15 lb. Bag Non-Toxic Barrier Is Permanent Protects Roots And Bulbs Safe For Use Anywhere In The Landscape Apply At Time Of Planting, Or To Existing Plants Directions For Installing PermaTill VoleBlock For Existing Plants: Dig a 'moat' around the plant just outside of the drip zone. The moat should be 10'-12"" deep, and 3""-4"" wide. Fill the moat with 100% PermaTill-VoleBloc to the soil surface and add a 1""-2"" layer of PermaTill as a mulch from the plant stems to the moat perimeter. For New Plants: Dig the hole 6-8” wider and 1” deeper than the root ball. Place a 2” layer of PermaTill on thebottom of the planting hole before setting the root ball in the center, allowing for a 3-4” wide moat of 100% PermaTill back fill from the bottom of the planting hole to the soil surface. Mulch the surface around the stems with 1-2” 100% PermaTill. For Bulbs: Dig the planting hole 2-3” deeper than required for the bulbs. Place a 2-3” layer of PermaTill on the bottom of the planting hole and set the bulbs directly on the PermaTill. Backfill to completely cover the bulbs with 100% PermaTill. Once the bulbs are covered, use a 50:50 blend of PermaTill and existing soil to fill the planting hole to the soil surface. As fragile as bulbs appear to be, they grow beautifully in the coarse PermaTill-VoleBloc barrier. Ships Quickly!"