Utah State University Extension provides informal education outreach to residents throughout the state. This question-and-answer column is designed to give you research-based information whether your gardening interest is producing fresh food, creating a landscape area or anything in between.
Question: I planted some pretty dahlias this year and I’ve heard I can save them for next year. How do I do that?
Answer: There are a few steps to follow if you want to save your dahlias and other summer blooming bulbs.
Once your dahlias have been nipped by frost, but before a hard freeze, cut the plants back to about four inches tall. Then carefully use your shovel to cut down into the soil all the way around the plant at about six to eight inches out from the stems of the plant. Once you’ve loosened the plant, use your shovel to gently pry underneath the root ball to lift the clump of tuberous roots.
Gently brush away the soil on the tuberous roots, being careful not to damage the skin. At this point, you can separate the clump into individual tuberous roots. Examine the clump of tubers carefully and look for eyes, or buds, at the top of the clump where the stem is attached. Some gardeners prefer to wait until spring to divide the clumps because the eyes may be more visible at that time.
Each tuber must have an eye. Any tubers that break away without an eye won’t grow when planted next year. Discard any material that is damaged or decaying.
Let the tuberous roots air dry for up to a day or two, but not for so long that they begin to shrivel, then store them in loosely covered pots, boxes or breathable bags of barely damp peat moss, vermiculite or perlite. The individual pieces shouldn’t touch each other. Don’t let the tuberous roots dry out. Store your containers in a dark, cool (45°-55°) location and check at least monthly to make sure the material around the tubers isn’t too dry or too moist. Spritz lightly with water if too dry, or open and ventilate if soil is too moist. Remove any tuberous roots that have begun to decay.
The process is similar for other summer blooming bulbs. Canna rhizomes should be cut back after a killing frost and then stored as described above.
Gladiolas should be cut back before a hard frost. Brush loose soil off the corms and let them air cure for a week or two in a warm location with good air circulation. One of the corms will look older than the others. Remove and discard it and store the large, younger corms in a mesh bag in a dark, cold, well-ventilated area.
Tuberous begonias should be dug before a hard frost, brushed off and stored in dry peat moss in a dark, cold location where they won’t freeze.
In the spring, you can plant your dahlias, cannas and begonias in pots to give them a head start before it’s time to transplant outdoors after the danger of frost has passed. Gladiolas should be planted directly into the garden in late spring once there is no danger of frost.
Question: I’d like to have something pretty on my front porch this fall and winter. I’ve had some potted plants there this summer, but they’re dead now.
Answer: This is the time of year when summer container gardens are losing their good looks, but you don’t have to give up on having something nice on your front porch. With the right plants and the right containers, you can still have something attractive by your door.
If you know you’ll be keeping your container garden throughout the winter, plan to use a container that will tolerate freezing weather. Most hypertufa, wood, plastic and concrete containers will do well in winter conditions.
There are several plants that will do well in autumn container gardens. Small evergreen trees and shrubs, either upright or spreading, look nice in porch containers. You can add color with mums, cabbage, kale, gourds and winter squash.
In our cold autumn weather, your plants won’t need much in the way of fertilizer, but you’ll still need to give your container garden regular care. Check the soil moisture weekly and water when the top couple of inches are dry.
Once winter weather sets in, you can replace any fading plants with holiday ornaments, dried berries, pinecones and other colorful objects. Containers on porches sometimes have enough protection to prevent the soil from freezing, so you’ll need to continue to check the soil moisture throughout the winter.
You can plant any perennials from your winter containers out into your landscape in the springtime when you’re ready for something fresh and new on your porch.