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Dahlias are perennial plants but they aren't winter hardy in our area. They need to be carefully dug up and stored safely indoors if you want to enjoy their blooms for more than one year.

Courtesy Meredith Seaver

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Late spring after the last frost is the time to plant dahlias, but fall is the time to dig and protect them so that they can bloom again next year.

Courtesy Meredith Seaver

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Dahlia plants and blossoms come in many sizes, shapes and colors, but they all need special attention in the fall if you want them to grow again next winter.

 

Courtesy Meredith Seaver

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Dahlias are a popular flower garden plant. They'll bloom from summer through the first frost. If you want them to bloom from year to year, you'll need to dig them up and protect them from our cold winter temperatures each fall.

Courtesy Meredith Seaver

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Question: I usually don’t dig up my dahlias until after a light frost blackens the leaves. This week, we had that hard freeze.

My plants looked great one day, and the next day, the tops were completely dead, and the soil seemed a little frozen when I dug up the tubers. Should I still try to store them for next year? How can I tell if they are still good?

Answer: I have the same dilemma with my own dahlias. You have nothing to lose by trying, and the dahlia tubers could be fine, but a careful examination will help you decide what to do.

The tubers should be firm and light brown in color. Sunken, dark, soft or watery-looking spots are signs of frost damage or disease.

Ideally, you’d dig the tubers after the leaves have been blackened by a light frost but before a hard freeze. Many parts of Utah County had a hard freeze this past week. A hard freeze can damage the tubers in the ground, depending on just how low the overnight temperature drops and how many hours the low temperature lasts. A thick layer of mulch can provide a few degrees of protection.

Saving your favorite dahlia’s tubers is pretty simple — dig, clean, divide and store — if you’ll follow a few basic steps.

Only save tubers from plants that were healthy during the growing season.

Start by cutting back the tops of the plants, leaving about two inches stem. If you have more than one variety, now is the time to put a label with each plant so that you can keep track of the varieties.

Dig down, carefully, all the way around your plant leaving about 12 inches between your spading fork and the main stalk, then angle under the dahlia and carefully lift the clump of tubers. Handle the clump carefully because the neck where the tubers are attached will be fragile at first.

Gently shake off loose soil. You can rinse off the clump to remove any remaining soil, but it’s important to let the clumps dry completely afterward. Many gardeners simply store the clumps of tubers without rinsing away the soil. Either way, handle the clump carefully to avoid damaging the skin of the tubers.

You can divide the tubers before you store them or wait until spring. If your dahlia only has a few small tubers, you can keep the clump the way it is. If your dahlia was very vigorous and you have a large clump of nice, plump tubers, you should divide the clump. Use a clean, sharp knife for the job. Each tuber needs to have a piece of the neck and some “eyes” (buds) or it won’t grow.

To store the tubers, you can spread them out in boxes or crates, put them in paper bags, and wrap them in newspaper or anything else that provides a little air circulation and keeps the tubers from touching each other. Keep them in a cool, dark place with good air circulation where moisture won’t condense on them, and they’ll be protected from freezing.

Check the tubers every month or so until planting time next spring, and discard any that show signs of decay.

Question: I shut down my sprinkler system last week. Now that I’m not watering any more, is there anything I should still be doing for my lawn for the next few weeks?

Answer: Our lawns will continue to grow for a few more weeks, so it’s important to continue mowing until it seems like growth has stopped.

Lawns should be mowed at about 3 inches to 3.5 inches tall during the summer, but set your mower height at about 2 inches for your last mowing of the season. This will reduce the risk of fungal diseases, like snow mold, in your lawn.

Keep the leaves that drop onto your lawn cleaned up. You can do this by raking, by mowing with a bagging mower, or if you don’t have very many leaves, you can take care of them by mowing frequently with a mulching mower.

Early in November, once the lawn has stopped growing and you’ve done your last mowing, you can do a fall application of nitrogen — about one pound of actual nitrogen for every 1000 square feet of lawn. The grass plants will store the nitrogen and use it to green up more quickly next spring.