ADAM’S NEEDLE
Native to the Mid-Atlantic and Southeast (and naturalized to the north and west of these regions), Adam’s needle, or Yucca filamentosa, grows as a rosette of upright, swordlike leaves. The species name refers to the curly threads at the leaf margins. This evergreen perennial’s spiky silhouette can help break up a border of soft shapes and fine foliage, and the leaves’ “mouth feel” makes deer and rabbits very unlikely to partake of them. Several cultivars have been developed for color or a neater habit.
Variegated options include ‘Color Guard’, which can reach four feet tall and bears a gold stripe down the center of each leaf. In the warmest months, the hue turns a creamier shade but remains undeniably yellow. ‘Golden Sword’ is similar in looks but smaller, growing two to three feet tall and with less stiff foliage. (Both these cultivars are sometimes sold as Y. flaccida. There is a history of debate as to whether the two species are distinct or flaccida is a variety of filamentosa.)
For a Y. filamentosa without gold markings, but still offering a little extra, ‘Excaliber’ stands out. This plant remains shorter than two feet. Its foliage is a bluish gray-green color that nicely sets off the many curly white filaments along its edges.
Adam’s needles are simple to grow. They prefer full sun but can take some shade. They need good drainage but otherwise put up with a range of soils. Highly drought tolerant, they form taproots that can make them hard to move (or remove), so choose their spot well. Bell-like flowers appear at the top of tall stems on mature plants (which live on after blooming, unlike the somewhat similar-looking agaves). These yuccas are hardy in Zones 6 through 10 and can survive a Zone 5 winter with protection.
Plants with silver or gray leaves are obvious choices for foliar interest in the sun garden, not just for their color but also their durability. Like everything in the plant world, silver foliage didn’t come about just to dazzle gardeners. In most cases the silvery look actually comes from adaptations to harsh conditions. Some silver plants have a waxy or filmy silver coating on their leaves to reflect strong sun. Other silver plants bear a thicker substance that helps to deal with drought; this silver fuzz catches rainfall, moistening the plant’s cells and then shedding the water toward the roots.
A particularly bright silver can be found in Artemisia ‘Silver Mound’. With its dense covering of very narrow leaves and rounded shape, it resembles a pompom. This low-growing perennial prefers heat and dry, poor soil. It performs best in Zones 3 through 7.
For a more subdued silver, there’s giant, or licorice mint, hyssop (Agastache rupestris), an upright perennial native to the mountains of the Southwest. Its threadlike leaves are colored grayish green, contrasting well with its own pinky-orange summer flowers. Hardy in Zones 5 though 8, it needs sharply drained soil and moderate moisture, though it can take drought.
Yarrows (Achillea millefolium) are often grown for their colorful, lacy blooms, but their foliage should be appreciated for its fernlike texture and gray undertones. The Sassy Summer’series, including red-flowered ‘Sassy Summer Sangria’ and yellowblooming ‘Sassy Summer Silver’, have a pronounced blue-silver tint to their leaves. Yarrows are drought-tolerant once established and low feeders, with a winter hardiness of Zones 3 through 8.
Chartreuse-hued foliage glows in the sun and combines well with all other colors of flower and leaf. Although not all lemon- or lime-green plants can take full sun, there are options that thrive in such a setting.
Lemony Lace elderberry (Sambucus racemosa ‘SMNSRD4’), a deciduous shrub growing three to six feet tall and wide, produces its lightest, brightest foliage in all-day sun (though it will succeed in part shade and benefits from such in the South). Leaves emerge with a reddish cast in the spring and take on deeper yellow tones in the fall. They offer intriguing texture thanks to their deeply cut edges. Horizontal branches create layers of leafy fringe. This plant appreciates regular watering and thrives in Zones 3 through 8.
Another sun-loving lime-green option is found in the ornamental oregano Origanum ‘Gilt Trip’. Reminiscent of a compact catmint (of which there are also chartreuse options), it has small, rounded leaves that line sprawling stems. Its loose, billowy habit makes it a good filler among tighter perennials. Bee-friendly purple blooms are a bonus to the leaves from midsummer onward. It prefers moderate water and poor to average soil. Its hardiness is Zones 4 through 9.
The genus Euphorbia is represented by species that vary wildly in appearance and use—the holiday staple poinsettia belongs to Euphorbia, as does the container go-to Diamond Frost. And there are hardy, shrubby euphorbias that make good foliage plants for the sunny garden.
Euphorbia ×martinii ‘Ascot Rainbow’ grows as a 20-inch clump of vertical stems lined with long, narrow leaves, colored sage green with a gold edge. Cool weather brings a reddish blush to the newest foliage. Some upright spurges benefit from cutting back after they bloom (a show of unique, brightly bracted flowers), but ‘Ascot Rainbow’ continues to look good without this treatment. Hardy in Zones 5 through 9, it needs excellent drainage and tolerates drought once established.
‘Glacier Blue’, often listed as a cultivar of E. characias, looks similar to ‘Ascot Rainbow’ except its foliage shows up blue rimmed in white. This evergreen perennial also stays a bit smaller, at 15 to 18 inches tall. It follows the same care regimen as ‘Ascot Rainbow’, too, although it’s not as hardy, with a rating to Zones 7 through 9.
Note: All euphorbias contain a sap that can irritate the skin, so wear gloves when working with them.
It can be difficult to come up with largeleaved plants for full sun. Shade lovers produce larger foliage as a strategy to capture as much light as possible; in the sun there’s no need for such an adaptation. Tender cannas and bananas can fit the bill, though, with impressive foliage that makes the extra steps to winter them worthwhile.
Cannas are grown for their luscious flowers as well as their leaves, which stand upright and can be found in a range of colors—sometimes several on one plant. Cannova Bronze Scarlet takes half its name from its leaf color, a handsome purple-brown, and half from its brilliant red blooms. Other standout cannas for foliage use include the Tropicannas—the original, with red, green and purple stripes; the lemon-and-lime Tropicanna Gold; and the midnighttoned Tropicanna Black. Cannas enjoy copious water and will thrive in poor drainage. In regions colder than Zone 7b, their rhizomes need to be lifted and stored indoors for winter.
Ornamental bananas (Ensete and Musa) also provide large leaves for the sunny garden. The red Abyssinian banana (Ensete maurelii) has propellorlike leaves in bronze-tinged green, with more sun bringing out more color. It’s hardy only to Zone 8 and warmer, and it may resist regrowing if dug for the winter. Keeping it in a large container that can be moved under cover solves this Northern problem.
There is a large-leaved sun-dwelling plant that’s actually perfectly hardy in most zones: hardy hibiscus, which combines traits of several North American species, including Hibiscus coccineus and H. moscheutos. Although the big, bright, tropical-looking flowers are a main draw on these plants, many cultivars have been developed to play up the appeal of the maple-like leaves.
‘Edge of Night’ is one example, with extremely dark leaves that set off its candy-pink flowers. This cultivar also boasts a smaller stature than older sorts, remaining under four feet tall. ‘Summer Carnival’ makes a splash through its variegated foliage, with pink and white markings at the edges of each leaf.
Garden varieties of hardy hibiscus descend from species that naturally occur in swampy areas, so these bulky perennials are not drought tolerant. They grow best in soil that drains well but remains consistently moist, and they will need watering in extended dry spells. They are slow to get started in the spring, delaying growth until even the latter part of June in Zone 4. Once they wake, they grow quickly. Most cultivars are hardy in Zones 4 through 9.