Velvety petals spread to a stunning 8 inches across on this dark burgundy Chinese hibiscus (Hibiscus rosa-sinensis) variety. The flower centers are nearly black, adding to the rich feel of this bloomer. Plants grow upward to 18 inches and then branch to create a spreading plant that looks good in a hanging basket or on an elevated stand so it can drape down.
‘Cobalt Dreams’ Delphinium
The flower spikes on ‘Cobalt Dreams’ stretch an impressive two feet, adding 2-foot towers of blue to plantings. This delphinium is part of the New Millennium Series, which tolerates heat and humidity, along with cold (hardy to Zone 3). Keep delphiniums looking their best by staking the hollow stems.
Also known as Egyptian lotus (Nelumbo nucifera), this beautiful pond plant actually hails from Asia and northern Australia. The striking flowers open in vivid rose shades, fading to pink. Blooms spread 8 to 12 inches across and release a distinct perfume. It’s hardy in Zones 4 to 10, as long as tubers don’t freeze solid in winter. In shallow ponds, relocate lotus pots to a non-freezing location for winter.
‘Casablanca’ Oriental Lily
Inject cooling white into your summer garden with the 10-inch-wide blossoms of ‘Casablanca’ Oriental lily. This perennial bulb produces stems 4 to 6 feet tall and offers a strong floral fragrance that fills the entire garden. Plant them near outdoor seating areas to savor the luxurious scent. Bulbs are hardy in Zones 4 to 9 and multiply freely from year to year.
Mammoth Russian Sunflower
It’s tough to top the oversize blooms of mammoth sunflowers. The Russian variety opens flowers to 14 inches across on towering stems 9 to 12 feet tall. This is the sunflower to grow to harvest seeds for eating. Sow seeds in spring for end-of-summer harvest.
A type of orchid cactus, the night-blooming cereus opens intensely fragrant flowers in the evening that fade with morning’s light. The pure white blossoms open to 7 inches across. The secret to savoring a heavy summer flowering season is winter growing conditions. Provide cool nights paired with soil that’s kept on the dry side.
‘Mrs. Edwards Whitaker’ Water Lily
One of the classic blue tropical water lilies, ‘Mrs. Edwards Whitaker’ is an heirloom variety dating to 1917. The sun coaxes flowers to open 10 inches or more across, revealing lavender blue petals that age to white. The center of the blossom offers bright gold stamens tipped in lavender. This fragrant water lily opens earlier in the day and remains open into early evening, longer than other tropical water lilies.
Ornamental onions fill the garden with fun spherical blossoms. ‘Globemaster’ opens its 10-inch- violet-purple orbs from late spring to early summer. The flowers stand atop 2- to 3-foot stems, like giant lollipops in the garden. They’re a favorite of bees and other pollinators. Bulbs are hardy in Zones 3 to 8.
‘Shimadaijin’ Tree Peony
Tree peonies open fragrant flowers measuring up to 9 inches across on plants that grow 4 to 5 feet tall. Colors include white, pink, yellow, red and magenta purple, like this beauty (Paeonia suffruticosa ‘Shimadaijin’). A mature tree peony can open more than 100 blooms in a growing season.
‘Indian Summer’ Rudbeckia
This classic summer flower brings the beauty of black-eyed Susan blooms to a larger-than-life size of 6 to 9 inches. The blossoms perch atop sturdy stems that are perfect for picking and spotlighting in vases. Plants are a short-lived perennial, sometimes returning from the root in Zones 3 to 9 and often self-sowing. This is a 1995 All-America Selections winner, which means it’s a strong performer in all parts of the country.
A panicle type hydrangea (Hydrangea paniculata), ‘Limelight’ is a shrub that gives and gives. The flower clusters vary from 8 to 12 inches long and open chartreuse, then fade to pink shades. The color lingers well into fall. A tough plant, ‘Limelight’ is hardy in Zones 3 to 8. Panicle hydrangea trains well into a tree form.
For pure summer flower power, it’s tough to beat dinnerplate dahlias. These over-sized blooms open to 8 or 9 inches across in a rainbow of colors. This pretty pairing features red ‘Alex Mingus’ and yellow and red ‘Lady Darlene’. Dahlias are hardy in Zone 9 to 11. In colder zones dig tubers and store over winter.
There’s a group of clematis known as large flowered types. ‘Fireworks’ falls into this group, opening blooms an eye-popping 6 to 8 inches across. Flowers open late spring to early summer and again in fall, showcasing lavender-blue petals with a bright magenta stripe. This perennial vine is hardy in Zones 4 to 10.
‘Primal Scream’ Daylily
Meet a daylily that commands attention with its color and size. Dazzling tangerine orange blossoms measure a whopping 7.5 to 8.5 inches across. The big flowers stand atop tall 34-inch stems. This daylily is a tetraploid, meaning it has four times the normal chromosomes--which can yield things like giant flowers. Look to other tetraploid daylilies for oversize blooms. Plants are hardy in Zones 3 to 9.
‘California Giant’ Zinnia
For really big zinnias, look to older varieties, like this heirloom variety introduced in 1919. ‘California Giant Mix’ Zinnia elegans features a blend of colors, including pink, white, purple, orange and yellow. The flowers open 5 to 6 inches across on stems up to 4 feet tall. This is the perfect zinnia for bouquets and also a hummingbird and pollinator favorite.