It’s easy to see why coneflowers have become such a mainstay of the summer garden and are among the perennials that forward-thinking gardeners are buying now.

As tall, purple daisies, they steal the show for a month or more when the heat settles in, bestowing an elegance not usually associated with wildflowers. At 3 to 4 inches across, the blooms are about the size of a rose but with the same distinctive architecture shared by others in the daisy tribe.

With coneflowers, mostly, the petals are a pink-purple, and the central disk is a copper orange. It’s an unlikely color combination, but it seems to work. Plant enough of them and you are guaranteed to draw goldfinches to the ripening seed heads.

A funny thing happened on the way to the meadow. A few years ago, breeders discovered that if you took the little-known yellow coneflower and crossed it with the purple coneflower, you got hybrids in shades of orange, red and yellow. This breakthrough set off a full-blown hybridizing frenzy that has produced coneflowers in salmon, orange-red, even chartreuse, with some priced at $20 or more per young plant.

The difficulty has been that coneflower fans — the original “coneheads”? — have been faced with a confusing array of varieties, many of which don’t perform that well. They can flop, be shy to bloom or simply rot away in heavy clay soil, especially in winter.

“Plants weren’t as good as advertised,” says research horticulturist Peggy Anne Montgomery. She works for Mount Cuba Center north of Wilmington, Del., where native plants are grown, displayed and evaluated.

Her colleagues spent three years testing five species and 43 cultivated varieties to see how they perform. The evaluators were looking for coneflowers that, beyond the beauty of their habit and blooms, were durable, didn’t need staking and were resistant to a stunting disease spread by a pest called the leafhopper.

Here are some of the highly recommended top performers:

PURPLE-FLOWERED

Pixie Meadowbrite. A short, remarkably floriferous hybrid, it has rosy-pink blooms with reddish-brown cones. Its compact size would make it a good candidate for the small city garden.

Pica Bella. This is a taller coneflower with large blooms on dark stems. The color is described as pinkish-magenta.

Elton Knight. Another compact coneflower, this variety has rounded overlapping petals to give a fuller floral effect. The color is a brilliant magenta.

Fatal Attraction. Big and showy, this variety is valued for its upright habit and bright purple-pink blooms held well above the foliage on strikingly deep burgundy stems. The petals are held out, not down.

Vintage Wine. Tall and dark-stemmed, the plant is similar to Fatal Attraction except the petals are short in relation to the large reddish-orange cone.

NOVEL COLORS

Of the novel-colored varieties, the testers liked Sunrise as a yellow form. Its large blooms open a rich medium-yellow, aging to a buttery yellow. It is more dependably upright than other yellow varieties, as well as its parent, the yellow coneflower.

Among orange flowers, the vote was for Tiki Torch, which doesn’t flop, is disease resistant and holds its petals out rather than down.

If you like your coneflowers more a clear pink than magenta or purple, Hope is an enticing variety, with broad overlapping petals, and the blooms are held high.

During the course of the trials, new coneflower varieties entered the bazaar, including an orange-red one named Tomato Soup, which looks as savory as its name.

A coneflower that has really stolen my heart in the last couple of years is the species Tennessee coneflower. It’s pinkish-purple with petals that are not only notched at the tips but also separated to form a pinwheel. The difficulty with this plant is that it is endangered in the wild, so it should be purchased only from reputable nurseries that have raised plants without collecting from the wild.

I think too that the plain old purple coneflower is a wonderful garden plant in a sunny bed, especially since it makes babies that grow true. However, a richer color would elevate the plant to perfection. The bottom line is that if I were replanting my coneflower bed, I would stock it with Pica Bella and Fatal Attraction.

GARDENING TIP

Buddleia, or butterfly bush, remains bushier and more floriferous if it is pruned regularly. The first spring flush of growth should be cut back now by half to promote branching. Prune just above a leaf. In a month, trim again. When flowers appear in midsummer, remove the fading blooms to encourage a new flush of blossoms in early fall.