Canna lilies are delightful flowers, and few species of flower can rival the burst of color they lend to summer gardens. But if they have overgrown your garden or otherwise outlived their welcome, eventually you may find it's time to get rid of them. Since canna lilies grow from an underground rhizome, killing them is not as easy as cutting back the foliage. It may disappear for the rest of this season, but it will be back next year, as vigorous as ever. To permanently get rid of canna lilies, you must literally get to the root of the matter.
Water the soil thoroughly the evening before you dig. This will loosen and soften the soil, making the canna bulbs much easier to dig up.
Cut the canna lilies' foliage back before you dig. This beauty's leaves can get quite large and you'll have an easier time of it if they're out of your way.
Use a spade to dig around the canna, a few inches away from its base. Once the soil is loose enough, remove the bulb by pulling it out by the foliage stub you left behind.
Use your spade to dig around the hole that used to house the canna bulb in a circle that is 1 foot or so in diameter. There may be some bulblets or bulb pieces in the soil next to the parent bulb. Remove these pieces or they will grow new canna bulbs next season.