The Distance From a Raised Septic Field for a White Spruce

Recommended Planting Distance

• According to Susan D. Day and Ellen Silva of the Virginia Cooperative Extension, trees should be planted as far away as possible from the drainfield to ensure that roots will not penetrate the field. They suggest estimating the mature root spread of the tree, which is approximately reflected by the mature height of the tree. White spruce typically grows 40 to 60 feet tall, although there are shorter cultivars of white spruce that are commonly available. White spruce can be planted closer the field if homeowners are willing to risk root intrusion, or they can lower the likelihood of intrusion by using proper soil preparation techniques and installing a root barrier.

Soil Considerations

• Soil type, depth and quality impacts the spruce's root growth habit and should be taken into consideration when selecting a planting site for the white spruce. In shallow soils, the spruce roots grow flat and spread farther near the soil surface, making these trees more susceptible to blow-down. The nutrient-rich and permeable drain field is more vulnerable if the soil is poor. On rich, deep soils, the spruce root mass is heart-shaped, and roots penetrate deeper rather than spread widely.

Soil Preparations

• Proper soil preparation will discourage spruce roots from penetrating the drainfield. Roots tend to locate and grow where the soil is least resistant, so ensure that soil away from the field allows adequate root growth. Dig as large a planting hole as possible, and concentrate on preparing the soil especially well on the side of the spruce facing away from the septic field. Prior to planting, consider amending the area with organic matter.

Root Barriers

• Root barriers are geotextiles that are generally impregnated with a long-lasting herbicide. This fabric is buried so that it extends from the root surface down at least 2 feet. The barrier should be located at least 3 feet away from the septic field and at least 5 feet from the tree. Do not encircle the tree with the root barrier. Properly-installed root barriers are effective, but the initial cost can be high.

Other Tree Species

• Some trees are better-suited than others for sites near drain fields. The Virginia Cooperative Extension considers the following trees best-suited for planting near drain fields: pines, hemlock, dogwoods, cherries, crabapples, sourwood, and red, scarlet and white oaks. Avoid planting beeches, willows, birches, elms, poplars and certain maples near the septic field.