The 10 best plants for beneficial borders
Here are the top ten ornamental plants we recommend for Beneficial Borders. All are very easy to grow and ideal choices even for new gardeners.

Bachelor's Buttons or Cornflower (Centaurea cyanus) This beautiful blue wildflower has extrafloral nectaries, which means the plant's leaves release nectar even when the flowers are not blooming. Research in Germany has found that bachelor button nectar has a very high sugar content of 75 percent. This nectar is highly attractive to flower flies, ladybugs, lacewings, and beneficial wasps. Sow easy-to-grow bachelor's buttons seeds directly in the garden in fall or early spring; plants usually reseed energetically.

Sweet Alyssum (Lobularia maritima) This low- growing annual makes a lovely white, highly fragrant edging for flower beds, or a fast-growing, beneficial-attracting, weed- smothering ground-cover to interplant in vegetable beds. Numerous studies have confirmed that sweet alyssum is highly attractive to aphid-eating flower flies. You can start with seeds, or buy bedding plants for earlier flowering.

Borage (Borago officinalis) This annual herb has bright blue clusters of edible, cucumber-flavored flowers. Studies in Switzerland have shown borage to be exceptionally attractive to good bugs, with an average of over 100 beneficials found in just 1 square yard of borage. In addition, common green lacewings have a very strong preference to lay their eggs on borage. Look for borage on garden center seed racks and mail order seed catalogs.

Cup plant (Silphium perfoliatum) This 6 to 8 foot tall native perennial has a unique feature that makes it a star in Beneficial Borders. The leaves wrap all the way around the stems, forming a deep cup that collects dew and rainwater. Beneficial insects and small birds can easily use the leaves as landing pads, and then drink from the cups. Cup plant is an outstanding ornamental, with large attractive leaves and clusters of yellow flowers in mid to late summer that are highly attractive to many insects. It's hardy to zone 4 or 3. To start seeds, sow in fall, or store in damp sand in the refrigerator for 6 to 8 weeks before planting in spring.

Anise Hyssop (Agastache foeniculum or A. rugosa, aka Korean mint) Perennial, summer-blooming anise hyssop has fuzzy purple or violet flower spikes on 2 to 3 foot high plants with licorice-scented leaves. The nectar-rich flowers are very attractive to both butterflies and pest-eating beneficial insects. Anise hyssop is hardy in zones 6-9; Korean mint in zones 5-8.

Golden marguerite (Anthemis tinctoria) This long-blooming perennial produces bright yellow 2 inch daisies that are highly attractive to five key kinds of beneficials—ladybugs, lacewings, flower flies, tachinid flies and mini-wasps. It was the only plant out of 170 species to score this well in a 3-year study at botanical gardens in Colorado and Wyoming. Golden marguerite thrives in poor soils, growing 2 to 3 feet high and wide. Deadhead (remove spent flowers) to promote rebloom, and divide plants every 2 to 3 years. Hardy in zones 3 to 7.

Fennel (Foeniculum vulgare) Long-lasting fennel flowers are extremely attractive to all nectar-feeding beneficial insects, and the feathery green or purple foliage looks wonderful in spring and early summer. Fennel is a host plant for the caterpillars of the anise swallowtail butterfly. The seeds and leaves are also eaten by humans, and are excellent in salads (leaves) or spaghetti sauce (seeds). The plants grow about 5 feet high and are perennial in zones 6-9.

Mountain mints (Pycnanthemum virginianum and P. muticum) Both of these native mountain mints (and many other members of the mint family) are excellent choices for Beneficial Borders. Short-toothed mountain mint (P. muticum) has broad clusters of small white flowers surrounded by unique, showy white bracts; it makes beautiful dried flowers. Mountain mints grow 2 to 3 feet tall and are hardy from zones 4 to 7. Not yet widely available, these plants can be ordered from Sunnybrook Farms, 440-729- 7232.

Pussy willows (Salix species) Willows are especially valuable because they produce pollen so early in the spring, when many beneficials are just emerging. Pussy willows are super-easy to grow and fun to cut for flower arrangements. Most garden centers will carry pussy willows in spring, or you can root cuttings from a neighbors' shrub in water.

Ornamental grasses All clump-forming grasses provide excellent summer shelter and overwintering sites for ground beetles, ladybugs and other beneficials. Studies in England found more than 1,500 predators per square yard in grass-covered "beetle banks" planted in arable fields.

Corn Corn tassels produce large amounts of pollen that is a nutritious protein source for many beneficials. And while we usually don't think of corn as an ornamental, it's actually very striking when planted in flower beds. Think of it as a very fast- growing, tall ornamental grass. And if you want an extra bit of beauty, try the 'Japonica' corn which has green, white and pink variegated leaves.