By JIMMY ROGERS
Few areas challenge gardeners like the strip of land closest to our homes. Builders will often plant shrubs to screen the unadorned foundation of a new house, and this sets the tone for how many of us continue to maintain that area. Let’s walk through some of the surprising complexities of foundation beds and how to plant for success.
Like any garden area, we must first consider conditions before planting. Builders usually use backfill, a mixture of the material originally excavated during construction, to underlay the lawn and garden areas closest to the house. In Maryland, this soil usually has a high clay content, which withholds water from foundation plantings. Additionally, many foundation beds are positioned directly against a house and partially covered by a roof overhang; this creates what we call a rain shadow, an area where rain never strikes the ground. And unless trees shade a foundation bed, it receives a good deal of sun for as much as half the day. These conditions combine to create a sunny, hot and dry bed where it can be challenging to establish new plants.
Once construction is complete, builder-installed gardens at new homes often include boxwoods (Buxus sempervirens) and other waxy, evergreen shrubs that can survive in harsh environments. Nandina (Nandina domestica) is often used, possibly because their presence is considered a sign of good fortune in front of Japanese homes. However, nandinas are an invasive species here in America and their red, cyanide-laden berries are toxic to dogs — and to some birds, notably cedar waxwings. Look out for burning bush (Euonymus alatus) in your foundation planting as well, another invasive shrub.
These shrubs can help screen a foundation from the road, and together with a lawn, they can create a uniform, static look reminiscent of European formal gardens. But they add little personality, must be regularly pruned and look noticeably uneven if one shrub in the bed dies. A replacement can take a long time to fill in the space and restore the look.
So what are we to do with this tricky area? First, I recommend reevaluating the layout. Any plants directly against the wall of a house are harder to maintain because you can only access one side. Consider creating a utility corridor between the foundation and the back of the bed; this space will make it easier to weed, prune and plant from both front and back. If you have a rain shadow, consider setting the bed far enough forward so rain reaches all of it. Some homes already have a corridor like this where the builders installed a strip of gravel to catch rain from the roof, thus preventing backsplash against the foundation from rain hitting soil.
After redesigning the layout, you can reimagine the aesthetic. Few native shrubs keep their leaves all year round, and those that do, like inkberry (Ilex glabra), require periodic cutbacks to remain dense like European evergreens. Instead of going for an “all green, all the time” look, you can welcome seasonal changes with colorful fall leaves and the sculptural beauty of stems in winter.
If you’re looking for a taller shrub, ninebark (Physocarpus opulifolius) is an excellent choice. It excels at growing in dry, sunny conditions and, with roots as deep as 16 feet, it doesn’t wilt during a drought. Ninebark drops its leaves in fall to reveal exfoliating bark, much like that of a river birch. It can also be pruned to size without too much trouble. I recommend planting only the straight species, which offers broad benefits to wildlife, rather than a cultivar.
On the end of a bed, I love to see a mass of shrubby St. John’s wort (Hypericum prolificum). Its yellow flowers will dazzle visitors in mid-summer, and it stays low for a number of years, generally topping out at four feet. It too tolerates dry conditions.
Perhaps the most dominant landscape feature of the traditional foundation bed is mulch. Homeowners often plant shrubs and then cover any exposed ground with wood bark mulch, the part of the tree that repels water. For a more vibrant garden space, you can turn to native herbaceous plants and grasses instead of annual mulch. Adding more roots to the soil around your shrubs will make the ground more porous and able to absorb rainfall. Foliage also reduces the temperature outside much more than turf grass or mulch, an increasingly important factor in our changing climate.
When considering herbaceous plants, look for those with a maximum height lower than that of your shrubs. False sunflower (Heliopsis helianthoides), New England aster (Symphyotrichum novae-angliae) and goldenrods, like showy goldenrod (Solidago speciosa), will combine into a late-season display. Taller native grasses such as switchgrass (Panicum virgatum) are also deep-rooted and can help fill vertical spaces.
I also frequently see foundation bed edges mulched when they could be planted. Short perennials such as moss phlox (Phlox subulata), plantain pussytoes (Antennaria plantaginifolia) and blue-eyed grass (Sisyrinchium angustifolium) can tolerate a lot of dry sun and will bloom in the first half of the growing season. You can also plant taller species such as perennial black-eyed Susans (Rudbeckia fulgida) and blue mistflower (Conoclinium coelestinum) that can grow right up against a lawn or pathway border, though you may need to trim fallen stems later in the season.
However you approach your foundation beds, I hope you will pause to examine whether that area is supporting wildlife and fits into your larger goals for stewarding your land. No one will arrest you for digging up those boxwoods, I promise.