By Marty Ross
Summer bulbs come from places where frosts occur rarely, if ever. But they’re right at home in the Midwest, where summers are bright and hot. Although these bulbs don’t survive winter in our climate, they put on a terrific show for a season. Now is the time to plant them.
Cannas, caladiums, dahlias, and gloriosa lilies aren’t true bulbs. Technically they’re tubers, like potatoes. Cannas are sometimes called tuberous rhizomes. To grow these magnificent summer bulbs successfully, all you need to do is plant them where they thrive. They do fine in pots.
CALADIUMS aren’t grown for their flowers but for their fancy foliage. Each tuber produces dozens of flashy, large, shield-shape leaves. Take a close look at the tuber and you see small growth eyes. This is the top of the tuber. Plant in shade.
The colorful label on the caladiums I found at Lowe’s this spring has a ruler on the back, so it’s easy to make sure you plant your tubers correctly. You should plant them 1 to 3 inches deep, firmly in the soil, with the eyes up. Caladiums are spectacular in pots, and you can crowd them together, with three to five tubers in each pot.
Caladiums’ leaves are almost always variegated. You see flashes of green—but white, pink, red, and even purple are typical. Usually the colors emphasize the veins in the leaves, or dramatically outline their edges. Go ahead, mix and match: They all look great together.
DAHLIAS flourish in sunny gardens when the weather gets hot. They grow from bizarre-looking tubers, like sausages tied together to a central stem. They produce many blooms from summer through fall. Handle the tubers gently, so they don’t break apart.
Plant dahlias with their crowns about an inch below the surface of the soil. If you see pale stems growing from the cluster of tubers, bury them when you plant.
Check the label when you plant to see how tall you can expect your dahlias to grow. Some are quite tall. If your dahlias are tall varieties, put a sturdy stake in the soil at planting time. If you wait until the plants grow tall, you could damage the tubers when you drive in a stake.
GLORIOSA LILIES live up to their name. Their ruffled, recurved petals are bright red, with wavy edges of lemon yellow. These flowers need full sun, and bloom from midsummer to late summer. They’re climbers, which is great for small-space gardeners. The vines get to be 3 to 6 feet tall over the course of the season.
The pale tubers of gloriosa lilies look a little like fingerling potatoes. They really have no tops or bottoms.
Plant gloriosa lily tubers horizontally, just a few inches deep, in a spot that receives full sun. Firm the soil gently over them, and water well. The first tendrils shoot up in no time. Gloriosa lilies bloom best when nights are cool, so their flower production may be best in late summer through fall.
CANNAS are spectacular, grown as much for their luxurious, almost tropical foliage as for their showy flowers. They’re great hummingbird attractors too. Many grow 4 to 6 feet tall, but some are under 3 feet. Usually the tubers have growing shoots when you buy them. Plant the tubers about 2 inches deep, with the green shoots upright. Cannas are sturdy plants and should not need staking.
When frost comes, tender summer bulbs are finished for the season. You can dig them up and store them over the winter if you like—or better yet, just start with healthy new bulbs next year. By that time you’ll be eager to experiment with something new.