Gardener’s Diary: What to do with canna lilies and dahlias

Gardener’s Diary: What to do with canna lilies and dahlias

Some of the plants that did so well this summer need to come in for winter.

A Gardener’s Diary

By Jocelyne Sewell

Some of the plants that did so well this summer need to come in for winter. What to do with canna lilies and dahlias for winter. Taken from The Encyclopedia of Organic Gardening:

“Cannas are perennials but will not survive our winters. The roots should be planted as soon as the soil has thoroughly warmed up in the spring. A good shovelful of compost should be mixed in the soil around each root. The roots may be started inside early in April. Use good soil in the pots with some compost mixed in. After warm weather comes, transplant them to the garden. With correct culture, each root division will have grown into a large clump by fall. On the morning you find the leaves frosted, cut off the stalks just above the soil line before the sun shines on them and turns them black. This improves the keeping quality of the roots. Lift each clump carefully, allowing some soil to adhere to it. One of the best methods of storing is to put the soil-covered clumps in boxes and cover with dry sand. A temperature of about 60F (15C) is best for storage. Cannas will rot at a low storage temperature and dry at a high one. The roots should be examined several times during the winter and the spoiled ones removed. Adjust the temperature if necessary. When planting time comes again, remove all dirt from the roots and divide them into sections with two or three points, or “eyes.” Each of these will grow into a stalk.”

Good tuber storage for dahlias starts with good plant care while the dahlias are still growing. If the plants are dug before they have a chance to go dormant in the ground the tubers are soft and will shrivel or rot easier. Allow your plants to sit in the ground for at least two weeks after they freeze or are cut down. I understand that this can be hard to do in some parts of the country. By doing these things we only lose around 1% of our tubers.

You do not need to divide your clumps before storing them but we advise it. If rot starts in the stem of a stored clump there is a chance of losing the whole clump. After dividing and marking the tubers, the cuts need to dry before storage. We store our tubers in plastic tubs, we use the shoe box size most often. We use plastic to avoid fungal growth. In the past, we used cardboard and had issues with fungus growing on it.

We have used peat moss and wood shavings in the past. With wood shavings, we had some fungus problems. We liked the peat moss but the tubers were stained dark and it became hard to find the eyes. We now use vermiculite it does not stain the tubers or promote fungal growth. Start by putting a layer of vermiculite in the bottom of the box then add the tubers and then add more vermiculite.

Put the lid on the box to help it retain moisture and store the tubers in a cool spot about 40F to 50F (5 to 10C). The lids should not make an airtight seal. Do not store your tubers in an area that freezes. When tubers freeze they turn to mush.

Check on the tubers every four to six weeks. If they are too wet leave the lid off until most of the moisture evaporates. If the tubers are starting to shrivel, mist them with water and replace the lid.

For more information call 250-558-4556 or email