Big Perennials for Big Impact

Perennial hibiscus may look like a tender tropical plant, but it's hardy enough to withstand winters to Zone 5. This giant plant bears 12-inch-wide flowers in stunning shades of red, pink, and white on stems that reach 7 feet or more tall. It's slow to emerge in spring, but once it does it grows quickly.

Name: Hibiscus moscheutos selections

Zones: 5-10

Grow a colorful and fragrant living screen with Oriental lilies. These hardy beauties grow 4-6 feet tall (or more) and produce huge flowers in red, pink, and white. The flowers are great for bouquets. Oriental lilies need full sun and moist, well-drained soil that's rich in organic matter.

Name: Lilium selections

Zones: 4-8

Attract butterflies to your garden with Joe Pye weed. It's a tough-as-nails perennial that will easily grow 7 feet tall. In late summer, the plant produces waves of nectar-rich pink flowers that butterflies love. Joe Pye weed thrives in moist, rich soil.

Name: Eupatorium purpureum

Zones: 3-9

Make stunning cut-flower arrangements with delphiniums. This summer-garden classic bears spikes of intensely colored blossoms in shades of blue, purple, white, and pink. The biggest varieties can reach 6 feet tall, though there are dwarf selections. Cut down spent blossoms to coax another flush of blooms.

Name: Delphinium selections

Zones: 3-7

Heat- and drought-resistant, easy-care 'Herbstonne' black-eyed Susan will add a burst of yellow to the back of the border. This perennial soars to 6 feet tall and bears bright blooms from midsummer to early fall.

Name: Rudbeckia 'Herbstonne'

Zones: 3-9

Lend old-fashioned charm to your perennial border with hollyhock. Known for its tall spires of colorful blooms, hollyhock is the perfect back-of-the-border plant. Old-fashioned selections can easily grow more than 6 feet tall in a spot with full sun and moist, well-drained soil.

Here's a hint: If you live in a windy area, you may need to stake hollyhocks to keep them standing upright.

Name: Alcea selections

Zones: 3-9

End your garden on a high note with boltonia. This underused North American native plant looks like a 6-foot-tall aster. It puts on a big fall show when covered in starry white or pink flowers.

Name: Boltonia asteroides

Zones: 4-9

Create color and interest in hard-to-landscape shady spots with goatsbeard. This 4- to 6-foot-tall plant looks like a giant astilbe with its finely divided foliage and early-summer plumes of creamy-white flowers.

Name: Aruncus dioicus

Zones: 3-7

Wow your friends with this amazing bulb. In summer, it bears spikes of up to 20 big white flowers with maroon stripes and a rich scent. The plant itself can easily reach 10-12 feet tall and thrives in moist, well-drained soil in partial shade.

Name: Cardiocrinum giganteum

Zones: 7-9

Give your garden a festive appearance with queen of the prairie's fluffy, cotton-candylike heads of fragrant pink flowers. This easy-growing wildflower has toothed, dark-green foliage that's a great accent to the blooms -- and a striking backdrop for other perennials.

Name: Filipendula rubra

Zones: 3-9

If you're looking for a perennial that you can grow like a hedge, giant knotweed may be the plant for you. This plant forms a thick clump to 6 feet tall and 10 feet wide. It bears airy white plumes atop its stems throughout the summer. And, happily, this knotweed doesn't seed aggressively like many of its relatives do.

Name: Persicaria polymorpha

Zones: 4-9

Plume poppy is the perfect perennial if you have a lot of space and want to make a big statement. It shoots up to 7 feet tall and bears airy clusters of flowers over big, tropical-looking leaves. One note: It's a fast spreader and needs lots of room to romp.

Name: Macleaya cordata

Zones: 4-9

Give your garden a touch of the exotic with gunnera. Everything about this perennial seems prehistoric, from its 6-foot-wide leaves to its weird flowers and spiny stems. Get an established specimen going in your garden and it might seem like a dinosaur could be hiding behind the 8-foot-tall mound.

Name: Gunnera manicata

Zones: 7-10

Add garden drama with cannas. Their big leaves and brilliantly colored blooms in shades of yellow, orange, red, and pink will instantly lend your garden a tropical feel. Dwarf cannas may only grow 3 feet tall; others soar to 8 feet or more.

Test Garden Tip: Make more garden magic by selecting varieties that have variegated foliage.

Name: Canna selections

Zones: 8-11; in colder areas you can dig and store the tubers in a frost-free place for the winter.

Standing tall over the prairies of North America -- or your garden -- cup plant bears golden daisies on sturdy 8-foot-tall stems from midsummer to early fall. Wondering where its name comes from? The upper leaves attach and clasp the stem, creating a "cup" that holds water for birds and other critters.

Name: Silphium perfoliatum

Zones: 4-9

Add an airy, delicate look to your landscape with graceful miscanthus. Its arching foliage and feathery summer plumes make it a great late-season privacy screen (it can reach 8 feet tall or more) or a soft backdrop for your favorite perennials.

Name: Miscanthus sinensis

Zones: 4-9

Here's a hint: Check the plant tag or description if you want a big variety; there are many dwarf selections bred for smaller gardens.

Bonus plant! While it's technically a perennial in the tropics, most folks grow castor bean as a fast-growing annual. This heat-loving plant can reach more than 15 feet tall in a single season. Be wary, though -- all parts of the castor bean plant are very poisonous.

Name: Ricinus communis

Zone: 10