Crabgrass, that notorious weed of opportunity, creeps in wherever it can find a foothold. Garden writer Barbara Damrosch advises that crabgrass is "happy filling in any bare spot on your lawn, garden or shrub border," adding that "the best prevention is to have no bare spots." Several attractive flowers and flowering ground cover choices exist to fill in those bare spots before crabgrass can.
While many people consider red or white clover to be mere weeds---perhaps even more undesirable than crabgrass---in reality clover acts as both cover crop and weed fighter by building nitrogen in garden beds, providing a tidy, colorful ground cover and effectively suppressing crabgrass. Choose perennial or annual clover seed, depending on how permanent you want the clover bed to be. According to author Toby Hemenway, clover makes a versatile weed-fighter because gardeners can easily tuck taller plants into the clover ground cover. In addition, both red and white clovers boast numerous uses once harvested, from health-giving teas to complexion-enhancing face rinses.
Among the most rapidly-spreading of all flowers, day lilies reliably choke out all manner of weeds, including crabgrass, because of their ability to thrive in almost any situation. Whether in damp or dry soil, part shade or full sun, the day lily not only thrives, but spreads rapidly. Plant day lily rhizomes in areas for which you want a taller, showier ground cover than clover or phlox. Day lily flowers come in a huge variety of color and heights, from the classic bright-orange variety to dwarf, lemon-scented cultivars. In addition, most day lilies bear edible petals and buds, making them even more useful than other ornamental weed-chokers.
They may look delicate, but daffodils and camas bulbs effectively fight crabgrass by muscling into their territory. Ornamental alliums, such as giant garlic and flowering chives, also make effective crabgrass-fighters. Keep in mind, however, that most of these bulbs flower early and go dormant in the summer, so pair them with summer-blooming bulbs, or with perennial plants that will quickly cover the spent flowers' browning foliage. This foliage, while still important for shading out crabgrass and other weeds, leaves much to be desired aesthetically. Hostas, tall bushy herbs like lavender or rosemary, or annual geraniums count among the dozens of plants that pair well with spring bulbs.
Flowering Ground Covers
Low-growing ground covers don't offer the nitrogen-fixing properties that clover does. But many gardeners consider them a far more ornamental way to fight crabgrass. For sunny sites, choose creeping phlox, chamomile, thyme, heather or bearberry. For part of full shade, consider ajuga, epimedium, lamium, lily-of-the-valley, lilyturf, periwinkle, lungwort or sweet woodruff. Because so many ground covers happily grow in shady situations, they make perfect choices for planting under trees or north-facing foundations, preventing crabgrass and other weeds from getting a toehold.