Planting shrubs near a home’s foundation enhances curb appeal, but improper spacing can lead to structural damage and poor plant health. Homeowners often plant too closely because they forget that the mature size of the shrub is the only relevant factor for long-term planning. Establishing the correct distance is a preventative measure that protects the structural integrity of the house and ensures the longevity of the landscape. This upfront calculation prevents the need for expensive foundation repairs or the premature removal of overgrown plantings later.
Calculating the Optimal Planting Distance
The minimum planting distance from a foundation is based on the shrub’s ultimate mature width, not its current size. The “half-spread rule” is a widely accepted guideline. It states that the center of the plant should be positioned at least half its mature spread away from the wall. For example, a shrub known to grow six feet wide must be planted a minimum of three feet from the foundation. This ensures the foliage will not press directly against the building material when the shrub reaches full size.
For air circulation and maintenance access, ideal spacing includes an additional one to two feet of clearance beyond the shrub’s mature radius. A five-foot wide shrub, for example, has a 2.5-foot radius; planting it four feet from the foundation allows for a comfortable 1.5-foot gap. This approach requires consulting plant tags or reliable horticultural resources to determine the mature height and width of the specific cultivar. Ignoring these ultimate dimensions is a common mistake that forces homeowners to constantly prune or eventually remove healthy shrubs.
Protecting the Foundation from Moisture and Root Intrusion
Planting dense foliage too close to the home significantly increases the risk of moisture damage and root interference. When shrubs are against the foundation, their leaves and branches trap precipitation and irrigation water. This prevents the soil and the wall surface from drying out. Sustained moisture compromises exterior waterproofing membranes and saturates the surrounding soil.
Water-saturated soil creates hydrostatic pressure, where the weight of the water pushes against the foundation walls. This pressure can drive moisture through minor cracks or porous concrete, leading to basement leaks or causing walls to bow inward. On masonry facades, trapped moisture can dissolve salts within the material, depositing them as a white, powdery residue called efflorescence. Roots of medium to large shrubs can also become problematic, especially in expansive clay soils. As roots grow, they draw excessive water from the soil beneath the foundation, causing the soil to shrink and potentially leading to foundation settling. While small shrub roots rarely crack intact foundations, they can exploit existing hairline cracks, growing into them and causing minor structural movement.
Ensuring Shrub Health and Maintenance Access
Proper distance from the foundation is paramount for the health of the shrub itself. When foliage is packed tightly against a wall, air movement around the plant canopy is severely restricted, creating a humid microclimate. This lack of air circulation prevents leaves from drying quickly after rain or watering, dramatically increasing susceptibility to fungal diseases. Common issues like powdery mildew thrive in these stagnant, moist conditions, compromising the plant’s appearance and longevity.
Sufficient spacing ensures the shrub receives uniform light and air exposure on all sides, promoting a balanced, healthy growth habit. The space is also necessary for routine homeowner maintenance and unexpected repairs. A minimum access corridor is required to comfortably paint siding, replace trim, inspect vents, or perform foundation repairs without aggressively pruning or removing a mature plant. Allowing space for the homeowner to work simplifies the essential task of pruning the shrub to maintain its shape and health.