You know that old saying that “friends don’t let friends grow annuals”? I now ignore that sentiment. Some of the best plants in my garden are annuals, and they are more than worth the effort of growing them every year. Annuals add bold color to my containers and beds, fill in spaces beautifully, and bloom for longer than any coneflower (Echinacea spp. and cvs., Zones 3–9) or phlox (Phlox spp. and cvs., Zones 3–9), so they bridge the flowering gaps between my perennials’ bloom times. But over the last few years as I’ve strolled the ever-more-homogenized aisles of the garden centers in my area, I’ve found myself bored silly, and in sticker shock. I always buy a few standard sweet potato vines (Ipomoea batatas cvs., annual), calibrachoas (Calibrachoa cvs., annual), and coleus (Plectranthus scutellarioides cvs., Zones 10–11), of course, but if I want something a little different, I grow it from seed.
Use Annuals Outside the Garden |
Growing annuals from seed neither difficult nor expensive. (See tips for growing annuals from seed here). Lots of annuals prefer to be sown directly into garden beds after the last spring frost, but even those that like to be sown indoors a little earlier are not a hassle. In general, annuals germinate faster and more readily than perennials, and they grow quickly without a lot of fuss. The following are the annuals I slip in to jazz things up a bit, to add some happy surprises and contrast. Whether unusual cultivars of an already-beloved variety or something completely different, they’re all destined to become your new annual favorites.
‘Cardinal’ Thai basil serves up visually yummy flowers in addition to edible leaves
Name: Ocimum basilicum ‘Cardinal’
Size: 2 feet tall and wide
Conditions: Full sun to light shade; moist, rich, well-drained soil
Native Range: Africa, Asia
I first fell in love with this plant at the Shelburne Museum in Vermont when I stumbled upon it in the display gardens. Who cares that it’s basil? The flowers are the main attraction. This lush large-leaved Thai basil variety is grown mostly for the wine-red, 2- to 3-inch-wide, tightly packed flower heads that appear among its bright green leaves. They’re spectacular in the garden and as cut flowers. But ‘Cardinal’ is not just ornamental; its leaves are also aromatic and delicious, enjoyed best just before the plant blooms. More dense and upright than other basils, ‘Cardinal’ also stays neat and tidy for longer. Use it in a mixed border, as an edible ornamental accent to your vegetable garden, or in large mixed containers for some extra spice.
▸ Sowing: To get the fullest plants the fastest, start basil seeds indoors 6 to 8 weeks before transplanting seedlings out into the garden after all threat of frost has passed. They should germinate in 5 to 10 days and grow quite quickly. Transplant to 18 inches apart in the garden.
Love-in-a-puff vine forms wonderfully decorative balloon-like seedpods
Name: Cardiospermum halicacabum* see invasive alert below
Size: 10 feet tall and 1 foot wide
Conditions: Full sun; moist, well-drained soil
Native Range: Mexico
Love-in-a-puff vine is the cutest, most romantic little plant. The fine, medium-green foliage scrambles delicately up any nearby trellis or string. Its tiny white flowers mature into pale green, 1-inch balloon-like lanterns (top) that gradually dry to the color of straw and contain two to three black spherical seeds, each emblazoned with an ecru heart (above right). Get it? Subtle, yes, but charming as all get out. This understated vine can easily get lost in a lush garden, so I grow it in a container with a tripod. In Zones 8–10 it can rampantly reseed, so steer clear of growing it in those regions.
▸ Sowing: Direct-sow after the threat of frost has passed, or sow indoors 8 to 10 weeks earlier. Seeds usually germinate in 7 to 20 days. Nicking the seeds with a file or nail clipper and/or soaking them in water for 24 hours before sowing speeds things along. Transplant or thin seedlings to about 6 inches apart.
‘Midnight Candy’ night phlox produces starry white blooms with an intoxicating scent
Name: Zaluzianskya capensis ‘Midnight Candy’
Size: 12 inches tall and wide
Conditions: Full sun; moist, well-drained soil
Native Range: Southern Africa
Night phlox is what dreams are made of. As the sun goes down, tiny burgundy buds begin to open until they reveal masses of starry white blooms that glow
in the moonlight. But it’s their fragrance that really rules the night. Sweet and intoxicating, it floats on the breeze, making one think of honey and freshly baked vanilla cake. The scent intensifies with the darkness until, near midnight, you’ll be swooning. I like to sow the tiny seeds of this little annual directly into a low, wide ceramic pot, in scant clusters 3 to 4 inches apart. I keep the pot in the shade until the seeds germinate and get established, then move it to my patio table so that I can enjoy the blooms and their heavenly scent as I sit with friends and family on warm summer evenings.
▸ Sowing: Sow night phlox indoors 3 to 4 weeks before transplanting
outdoors, or direct-sow in the garden after the last spring frost date. Seeds germinate within 7 to 10 days and transplant easily. Plant or thin seedlings
to 12 inches apart in the ground, closer in pots.
‘Harlequin’ French marigold prevents a summer lull with pinwheels of color
Name: Tagetes patula ‘Harlequin’
Size: 2 to 3 feet tall and wide
Conditions: Full sun; fertile, well-drained soil
Native Range: Mexico
If you think of marigolds only as bedding plants in six-packs with
ridiculously bright, beefy blooms, you have to try this one to see what marigolds used to be—and still can be. A gorgeous hot-colored bed filler, this 19th-century heirloom is an unusually tall and airy, bushy marigold. It sports fine, aromatic foliage and vivid, dainty, 1-inch gold-and-maroon-striped pinwheel flowers interspersed with solid maroon and solid gold flowers. At up to 3 feet tall, it combines with other plants gorgeously. Its long stems make it great for bouquets too. ‘Harlequin’ starts to really hit its stride at the height of summer’s heat, when other flowers tend to wilt. Add it to your sunniest, hottest beds for fresh summer greenery and a dash of beguiling hot colors.
▸ Sowing: Marigolds can be started either indoors or outdoors, depending on your preference. The seeds germinate quickly, usually within 3 to 5 days. Starting them indoors gives them a head start, but direct-sown seedlings will quickly catch up. Indoors, sow seeds 4 weeks before the last spring frost date. Outdoors, direct-sow about 1/4-inch deep after the last frost date. Thin or transplant to about 12 inches apart.
‘Mahogany Splendor’ hibiscus is a killer foliage plant in mixed borders and containers
Name: Hibiscus acetosella ‘Mahogany Splendor’
Size: 8 feet tall and 5 feet wide
Conditions: Full sun; moist, rich, well-drained soil
Native Range: Africa
If there were ever a plant that was the absolute biggest bang for your buck when growing from seed, it would have to be ‘Mahogany Splendor’ hibiscus. In one season it shoots up to 6 or even 8 feet tall. Grown not for its flowers but for its spectacular foliage, ‘Mahogany Splendor’ has maple-like leaves that are a dark burgundy-red-purple, which, surprisingly, goes with everything. This mass of dramatic foliage creates stunning contrast in borders and is a superstar in large-scale container plantings, where it sings when combined with colorful, sun-loving coleus and a multitude of vivid flowers. In a container, stems might need to be trimmed once in a while to keep its size in check, but those trimmings are a wonderful filler in large-scale bouquets. Once you grow this all-purpose stunner (a perennial in Zones 9–11), you’ll never go another season without it.
▸ Sowing: For the biggest, happiest plants, start seeds indoors under lights, at least 6 to 8 weeks before transplanting them out after the last frost. Sow the seeds in small pots or individual cell packs. They will germinate within 3 to 5 days and grow rapidly. As they grow, transplant them into larger pots, and fertilize at half strength weekly. Once the seedlings are about 6 inches tall, pinch back the tips of the growing stems
to encourage branching for fuller plants later. By the time they’re ready for planting out into the garden, they may be in 6-inch pots and be quite large.
‘Frosted Explosion’ switchgrass shines with striking texture in beds and bouquets
Name: Panicum elegans ‘Frosted Explosion’
Size: 24 to 36 inches tall and 18 inches wide
Conditions: Full sun; moist, well-drained soil
Native Range: United States
‘Frosted Explosion’ looks like fireworks in the garden. In late summer its mounds of medium green blades are topped with sturdy stalks of long-lasting, sturdy, buff- to pink-tipped blooms that resemble fiber-optic sparklers. It adds wonderfully fine, airy texture and long-lasting excitement to garden beds, but it’s an absolute dream in bouquets. Incredibly easy to grow, this ornamental grass is very productive and dries
well too. Hand a few flowering stems to the kids for a safe alternative to dancing with real sparklers on a hot summer night.
▸ Sowing: This switchgrass can be direct-sown after all threat of frost has passed, but for bigger plants, start seeds indoors in small pots 4 to 6 weeks before the last frost. Either way, sow seeds in small clusters, pressing them into the soil and covering them only lightly. They should germinate in 7 to 10 days. Transplant to 18 inches apart.
‘Purple Emperor’ nasturtium is a twist on the norm with its deep wine-red flowers
Name: Tropaeolum majus ‘Purple Emperor’, syn. T. majus ‘Summer Gown’
Size: 18 to 24 inches tall and wide
Conditions: Full sun; lean, well-drained soil
Native Range: Central and South America
In a sea of orange, yellow, red, peach, and salmon nasturtium blooms, ‘Purple Emperor’ is truly unique. Its delicate flowers open a deep wine-red (inset) and then age, in the most beautiful of ways, to rose, then to warm purple, and finally to pale lilac. It’s a fascinating transformation, one you’ll watch closely day after day and week after week. While many nasturtiums are compact and dense, creating a solid block of foliage and flowers, ‘Purple Emperor’ grows a little more loosely, so it mingles well with other annuals and perennials. As with all nasturtiums, every part of ‘Purple Emperor’ is edible. Hold off on fertilizing these plants, as they flower most profusely in lean soil. In rich soil you’ll get lush foliage but few flowers.
▸ Sowing: While nasturtiums can be started early indoors, they are happier from the start when direct-sown after the last spring frost date. Sow the jumbo, wrinkled seeds
1 inch deep, and keep the soil uniformly moist until the seedlings emerge, up to 10 days later. Thin the seedlings to 8 to 12 inches apart.
SunFill™ Purple sunflower is ornamental from bud to bloom
Name: Helianthus annuus ‘SunFill Purple’
Size: 6 feet tall and 11/2 feet wide
Conditions: Full sun; moist, well-drained soil
Native Range: North America
SunFill™ Purple sunflower has created quite the buzz with floral arrangers. Gorgeous early on, it flaunts a full, spiky ruff of large, dusky purple–tipped, gray-green tepals around a deep, dark center (right). It’s that look for which this sunflower is becoming -famous, but the later not-often-photographed stages of the flower are also fascinating. This is when its lemon-yellow petal tips begin to peek out before emerging as short, tubular golden petals surrounding a mahogany center (left). It’s said that Mormons scattered sunflower seeds along their journey to Utah so that others could follow their sunny path months later.
▸ Sowing: Direct-sow sunflowers every 3 weeks after the last spring frost date for continual blooms throughout summer. Seeds usually germinate within 10 days, even sooner in warmer weather, if the soil is kept evenly moist. Thin seedlings to about 1 foot apart.
*This plant is considered invasive in Texas.
Michelle Gervais is the horticulturist, editor, photographer, and resident seed-sowing fanatic at John Scheepers Kitchen Garden Seeds in Bantam, Connecticut. She is also the author of Design-Your-Garden Toolkit: Visualize the Perfect Plant Combinations for Your Yard.
Sources
• John Scheepers Kitchen Garden Seeds, Bantam, CT; 860-567-6086; kitchengardenseeds.com
• Johnny’s Selected Seeds, Fairfield, ME; 877-564-6697; johnnyseeds.com
• Select Seeds, Union, CT; 800-684-0395; selectseeds.com
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