Protecting Tender Bulbs

Cannas, gladiolas, dahlias, tuberous begonias, and in some colder parts of the country, calla lilies, agapanthus and eucomis (or pineapple lily) are examples of summer bloomers that need winter protection if you want them to survive.

Protecting Tender Bulbs by Digging Them Up

Once a bit of cold weather turns the foliage of a tender bulb gold or brown, this is your signal to dig in and uproot the bulb-like root growing underground. Dig a circle around the area where the roots are growing. Then, slide your shovel down under the plant’s roots. The goal is to pop the bulbs, soil, roots, and all out of the ground with one shovel scoop. Then you can use a hose or your hands to remove the soil from around the bulb.

Be sure to cut off any vegetation growing from the top of the bulb. This will leave you with a tuber or potato-like section of root. Store this root section in a cold but not freezing spot such as an unheated basement or garage. Place the tuber or bulb into a paper (not plastic) bag. The bulb should be kept just slightly moist but not wet. Plastic traps too much moisture and can encourage winter rotting or mold growth. Some gardeners pack their dahlias, glad, or begonia bulbs in crates of peat moss or sawdust for winter storage.

Protecting by Keeping the Winter Snow/Rain Out

If you don’t mind a bit of a gamble, you can simply cut the tops off of your tender bulbs. Then, cover the soil with an oilcloth, a tarp, or an upside down plastic pot to keep out the winter moisture. In many parts of the country it is the winter wet that rots the bulbs not the freezing cold that kills them. This method of winter protection only works if the bulbs are planted below the frost depth of your soil. The deeper the bulb is planted, the more likely it will escape frozen soil.

Cannas, begonias, and dahlias planted in containers can be moved to a protected area. These include a covered porch, covered, patio, under a table, or even the eaves of the house. Keeping the soil dry during the winter months may be enough to keep these summer bloomers alive.

Once spring arrives you can move the tender bulbs to a bright window inside the house. You can start them growing in fresh potting soil. If you decide to leave dahlias or cannas in the ground, you can remove the protective waterproof covering once all danger of frost has passed or when you see new shoots emerging from the ground in late spring.