A longtime love affair with cannas
Published 5:21 pm Friday, May 10, 2019
Back when I was even more amateurish as a gardener, I took up with cannas. I liked they were easy to grow and the best part back then was one could usually get some red ones free from somebody else’s yard and yellow ones were pretty cheap at the store. Then I added the orange, variegated leaf one plus a dwarf variety.
There are hundreds of varieties of cannas created in different parts of the world and some of them are super colorful. But I eventually got rid of all mine but one family keepsake salmon-colored one from my favorite uncle’s flowerbed. Easy-to-grow and colorful just wouldn’t overcome leaf-roller caterpillars.
The plants survived the worms every spring and summer, but the only thing that made my mangled cannas look decent to me was distance.
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Cannas were among the plants I mentioned last week that grow from rhizomes, not bulbs. They also make seeds and the only way new varieties are created by mankind is by controlled cross-pollination and planting the subsequent seeds.
While canna blooms and their rhizomes might make us think of irises, they are not in the same family.
Cannas are more closely related to banana and ginger. Native to the tropic and near tropic areas of South, Central and North America, cannas can’t survive year round in cold climates. Yet they are very popular in Europe and that’s where a lot of new canna varieties have been bred the last couple hundred years. In cold areas, canna rhizomes are dug up and protected over winter and replanted come spring.
Not here, but in some places cannas are grown as agricultural crops for food. The rhizomes are very concentrated starch sources.
Some folks somewhere cook and eat the tender new leaves. In different areas, the extremely hard seeds of canna are used as jewelry beads and canna plants are fermented into booze.
Back to the bugs: the southeast United States is known to have the world’s worst problems with canna insects. These include aphids and thrips, but the main culprit is the leaf-roller, which is the larvae stage of a certain butterfly species.
The larva chew through rolled up leaves before they unfurl, leaving a straight line of holes in opened leaves. And newer larva bite off bits of leaf and roll themselves in a leaf-web combo for protection.
Left untreated, cannas typically become ratty-looking and gnawed up by their summer bloom time. Since the caterpillar is a Lepidoptera (butterfly or moth) larvae, the organic insecticide Bt works for a control when a spray or dust can get to the larva. But the plant leaves and rolled-up shields are difficult to penetrate. That’s why the few cannas I keep around for old times’ sake are the only plants I treat with a systemic insecticide that moves from the soil by roots to the rest of the plant. I apply imidacloprid granules around the cannas in mid-March, mid-May and late June.
I have pretty canna leaves now.
Terry Rector is a columnist for The Vicksburg Post. His column appears in The Post each Sunday.