Cannas – Let’s Plant MoreMaster Gardener Scoop – September 1, 2016

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Cannas – Let's Plant More

By Leora McTall,

Master Gardener

Cannas have not been seen a lot here in our Irvington garden. There's one good reason – they must be stored inside for the winter. And that's a bummer. But, their bold, bright, tropical look cannot be rivaled by most hardy perennials. So things are about to change!

It all began in Springfield at our American Iris Society meeting two years ago. Members bring all kinds of plants, not just iris, for the auction which resulted in a small variegated, large leafed, un-named variety of canna coming home to Irvington.

The first year here the new canna just sat around looking pitiful. This year, after dividing it into five rhizomes and planting them in the planters on the deck, they stole the show! Two have grown to four feet with silky orange flowers. The other three plants are not quite that tall, but looking good just the same. So they just needed more room to thrive and full sun.

Now the research began because most plants here have a label, and friend Deb from Springfield did not know what variety canna she was donating to the auction. With striped leaves of dark green, light green and white, and flowers of orange, a good guess would be "Pretoria,” a/k/a "Bengal Tiger.”

As previously lamented, cannas need to be stored for the winter. What a hassle. Although last year when storing the six inch pot of canna rhizomes, it was just set in the garage as is and watered very little during the winter. Now after increasing in the larger planters, there are five masses of rhizomes. When the leaves become blackened with frost, stalks will be cut off then stored in slightly moist peat (or loose soil) and kept in the garage over winter. They must not freeze.

Our USDA hardiness zone six growing area is sometimes listed as safe for leaving cannas outside in the ground during the winter. It seems we are right on the edge, so keep in mind that you could possibly lose the plants if we have a very cold winter. If the plants are in a pot, they should be taken in. Another choice would be to treat cannas as annuals, and just let them go.

According to the University of Illinois, while in winter storage if rhizomes become anxious and start sprouting about March, break them apart and plant in containers until the danger of frost is past. Then plant them directly in the garden or in larger pots outside.

University of Illinois also states that "cannas may be grown in standing water if rhizomes are started in pots and submerged in water." So what a "wow" addition to a water garden!

The most exciting part of this story is next spring there will be many cannas to plant, all from this one small start, so the plan is to plant them throughout the garden and on the deck too. If there aren't as many as expected, maybe more will be purchased. Check out several sources before investing in cannas. They can be very pricey, or if you want the common but beautiful, tall, red blooming, green-leafed variety, they can sometimes be purchased for a song – even at a yard sale.

Mark your calendars for Saturday, September 24, 8:00 – 12:00, and come to the Master Gardener Plant Swap at the Nashville Library grounds during the Fall Fest. Bring a plant, take home a plant, and if you don't have a plant to swap, many are available for a small donation.

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Large-leafed variegated "Bengal Tiger" canna shown here on writer's deck with red salvia (for hummingbirds) and "Diamond Frost" Euphorbia.  Earlier silky orange flowers topped the stately canna leaves.  These canna rhizomes have multiplied over the summer and will need to be stored inside for the winter.