Canna Tropicanna®—Featuring the original Tropicanna canna with striped foliage and orange blooms, then Tropicanna Gold with green and yellow striped leaves and a yellow and orange flower, and at right, Tropicanna Black with dark foliage and a red bloom.
Cannas are spectacular summer bulbs. Paddle-shape leaves wrap in ruffles around stems, tapering to refined buds. The buds open into eye-catching flowers of red, orange, yellow, and pink from late spring or early summer to first frost. When most flowers can’t take the heat of late July and early August, cannas thrive.
Cannas are commonly referred to as “bulbs,” although they are not true bulbs. They multiply beneath the soil from a rhizome, an underground stem.
Canna leaves are often heavily veined, adding even more beauty, especially when backlit by the sun.
Canna is among the most colorful summer bulbs, as flamboyant as their tropical American ancestry. Learn how to plant, grow, and care for the cannas in your garden!
Cannas can be both focal points and stylish accents. Use them to bring structure as a tall border or to add depth to narrow spaces. Center them in large patio pots and surround them with bright annuals. Cannas bring a tropical touch to water features and they thrive in boggy areas. Indoors, display them in large containers near brightly light windows.
Canna blooms are flashy and flamboyant and stand tall on their stems. They would be magnificent even if they never bloomed. However, they keep pumping out colorful flowers from late spring or early summer to frost.
Mix cannas with grasses, lantana, zinnias, snapdragons, elephant ears, salvia, periwinkles and more.
Cannas will tolerate partial shade, but require at least 4 hours of direct sun. They need fertile, moist soil. Before planting, loosen the soil to a depth of 12 to 13 inches, then mix in 2 to 4 inches of compost.
When to Plant Cannas
Cannas cannot tolerate cold temperatures. Plant outdoors in late spring or early summer. Soil must be 60ºF or warmer. In short-season areas, start cannas in pots indoors or in a greenhouse to transplant outdoors at the right time.
Some people ask how to determine soil temps: Check online for state extension websites that publish this information for your state. Or, dig a small hole two inches deep and insert an old-fashioned mercury thermometer into your soil. Or, buy a soil thermometer at local nursery or hardware store.
How to Plant Cannas
Dig a hole 2 to 3 inches deep and set the rhizome in it, with the “eyes” (bumps or nodes, which are growth sprouts) pointed up.
Cover with 1 to 2 inches of soil, Tamp firmly.
Space rhizomes 1 to 4 feet apart.
If possible, position plants out of strong wind. Their large, soft leaves are vulnerable to damage.
Water thoroughly, then withhold water for as long as 3 weeks, and watch for signs of growth.
When planting new rhizomes, or those dug up and stored to winter over, make sure that each divided piece has at least one eye. From it, new leaves will grow.
Blooms should appear in 10 to 12 weeks..
Canna ‘Tropicanna’® planted among sedum ‘Autumn Joy’ makes for a stunning display in late summer.
Turn-of-the-century gardeners so loved cannas that they grew them from seed, but this isn’t easy; better to leave propagation to experts and plant canna rhizomes instead.
If you grow from seed, be aware that the germination rate is low and the seeds need to be filed or given an acid bath to break down their hard coat.
During the hottest weeks of the summer, give the plants a good soaking drink of water every other day.
If rainfall is less than 1 inch per week, water. Provide a good soaking every other day during the hottest weeks of summer. Water freely in dry spells.
Once sprouted, water at least once a week by slowly soaking the area around the roots.
Maintain a thin layer of mulch to help retain moisture.
Stake tall varieties, if necessary.
Where the soil is fertile, fertilizer is optional.
If desired, apply a 5-10-5 or 10-10-10 fertilizer in spring and twice during the growing season.
Fish emulsion fertilizer, a little higher in nitrogen, is a beneficial organic alternative. Higher nitrogen fertilizers tend to increase canna height. Rose or tomato food products are also suitable.
As flowers fade, deadhead to promote continued flowering.
After it has been deadheaded several times and with flowers no longer forthcoming, cut the flower stem back to the foliage.
Full foliage color develops when days are warmer (59ºF or more). .
Digging and Storing Cannas for Winter
Bring cannas grown in pots into a garage or basement for winter. Keep them dry. When spring’s nighttime temperatures are consistently above 50ºF, typically after the tulips have bloomed in northern areas, you can move them outdoors. Only then move them outside for the summer.
In northern areas that experience harsh winter conditions, it is necessary to dig up (lift) in-ground cannas in the fall and bring them inside for the winter.
Generally, this means Zone 6 or colder, although Zone 7 may also occasionally experience canna-killing winter temperatures. In Zone 7, it’s a bit of a toss up. Add a layer of straw or leaf mulch to protect your cannas, or dig them up to be safe.
In Zones 8 and warmer, cannas can be left in the ground year-round.
After the first fall frost kills the foliage but before a hard freeze occurs, cut in-ground plants back to 4 inches. It is not essential for canna foliage to be frosted prior to digging, but this is recommended.
Plunge a shovel or garden fork into the soil about 1 foot away from the stem, to avoid damaging the rhizome.
With your hands, gently loosen the soil and lift out the clump. Shake off the dirt and cut off the foliage.
Divide clumps into 3 to 5 rhizomes, each with eyes.
Cure the rhizomes in the sun or in a garage or closet for a few days to toughen them up and help them to resist rot.
Wrap each rhizome in newspaper or a paper bag, along with a small about of dry growing medium, such as peat moss, to absorb moisture and prevent rot. Rhizomes should not touch each other.
Store cannas over the winter in a dry place where the temperature will not drop below 40º. Often this is an attic or basement.
Check the rhizomes a couple of times over the winter to make sure that they don’t dry out. Mist with a bit of water, as needed.
If you find rot, trip it away or discard the entire rhizome. It is common that not all rhizomes will survive in winter.
When replanting, make sure that each divided piece has at least one node, which is where new leaves will grow from in following seasons. Then plant 4 to 5 inches deep and 1 to 4 feet apart. They will bloom in 10 to 12 weeks.
See Harvest/Storage (below) for more instructions.
For a tall canna, the Canna Tropicanna® is a popular choice. Growing to a height of 48 to 72 inches, ‘Tropicanna’® boasts gorgeous tangerine, iris-like blooms and exotic bronze foliage. Plant in the back of your garden bed or in large containers for a dramatic statement on your porch or patio. Don’t worry about deer; they tend to stay away from easy-to-grow cannas.
A medium-size gem is the rich, deep pink ‘Los Angeles’, which has a large floret and opens out so that you can see the face. The plant grows from 42 to 60 inches tall, blooming from June to August.
Image: Credit: Mick49/Shutterstock
As well as the medium- to tall-size canna, you can find smaller “dwarf” sizes and dramatic “giant” sizes!
Dwarf cannas stay under 3 to 4 feet tall and are easy to fit into our downsized modern gardens. The ‘Picasso’ is a real attention-getter with bright yellow flowers and deep red leopard-like spots; it blooms from July to frost. The ‘Wyoming’ has dark burgundy stems and lush orange flowers that brings life to a quiet bed from mid-summer until frost.
Interested in a giant canna? One of the most popular is the ‘Musifolia’ which grows up to 8 feet. Its leaves are the size of a banana plant and creates dramatic statement and very tropical background!
Cut canna flower stems for indoor arrangement. The flowers carry their tropical appeal in the vase. The flowers die in a day or two. However, the foliage continues to make a beautiful backdrop to many bouquets.