Does your perennial bed cry out for color during that stretch of summer between Independence Day and Labor Day? Then plant some annuals. They flourish in hot weather, high humidity, and even drought. Plus, its easy to add annuals right where you need a punch of color. And if you don't like the combinations you create, it's easy enough to switch things up next year.
We've matched some commonly grown midsummer perennials with annual plants whose color, height, or structure look good together.
Black-eyed Susan (Rudbeckia fulgida). 'Bright Lights' cosmos, globe amaranth, tall cigar plant, and salvias all have colors and shapes that play well off those challenging yellow-orange petals with black centers.
Catmint (Nepeta). Unless it's cut back in late spring, catmint goes to ground—that is, it flops. Let it recline on a chartreuse sweet potato vine (used as a groundcover). Also try 'Profusion White' zinnia or annual black-eyed Susan. Cardoon echos the catmint's silvery foliage, but contrasts in size and shape.
Coneflower (Echinacea). These look stiff and brittle to me, so I surround them with plants that look like they're giving them a hug: pincushion flower, lantanas, tropical smoketree.
Coreopsis. Most coreopsis, be they bigleaf or threadleaf, have yellow or gold flowers, so anything that flowers in blue or purple looks good, including angelonia or salvias. Cigar plant flowers in orange and yellow-pink, so it harmonizes and contrasts at the same time.
Daylilies (Hemerocallis). The straplike foliage contrasts well with copperleaf, dragon wing begonia, and anything else that grows up instead of down.
Lilies (Lilium). Upright growers with trumpet-shaped flowers that emerge along the top of the stalk. Cover their spindly stems with full foliage: tropical smoketree, flowering tobacco, taro, copperleaf.
Rose campion (Lychnis). Soften the screaming magenta flowers of rose campion with spider flower, 'Ace of Spades' pincushion flower, or beets. (Yes, beets. 'Bull's Blood' and 'Ruby Queen' have terrific red leaves.)
Russian sage (Perovskia). Sprawling, weedy-looking Russian sage works alongside any daisylike annual, hyacinth bean vine, sweet potato vine, or annual black-eyed Susan.
Salvias. Upright, spiky-growing perennial salvias look good next to anything with mass, including cardoon, spider flower, cosmos, and annual black-eyed Susan. Try creeping zinnia in front as a groundcover.
Shasta daisies (Leucanthemum). Anything looks good next to them, even another daisy-flowered plant, as long as the flowers are different sizes. Go with spiky, broad, or straplike plants, including angelonia, lion's ear, lantanas, and salvias.
Yarrows (Achillea). Upright-growing yarrow's flat-topped flowers are its fullest part, so pair it with spiky plants like New Zealand flax. Annual black-eyed Susan, as well as castor bean (which comes into its own as the yarrow's flowers fade), will also complement yarrow's form.