Bring tender perennial potted plants into shelter for winter.
Just like perennial plants, some garden questions come up year after year. How to keep geraniums, fuchsias and dahlias from dying over winter is one of them.
“Some plants are what we call tender perennials and are living outside their hardiness zone,” said Brooke Edmunds, horticulturist for Oregon State University’s Extension Service. “In most places in Oregon, that includes geraniums and fuchsias. If we get a cold snap, they’ll have problems and most likely die.”
To keep that from happening, bring potted plants into shelter for winter, she said. But keep in mind each plant needs different conditions.
Geraniums — more accurately pelargoniums — continue to grow throughout the cold season, albeit slowly. Fuchsias go dormant in cool weather so need less fuss. Dahlias, which are tubers, need even less attention and can be dug up and stored like potatoes.
For geraniums, Edmunds advises moving them into a bright spot in the house or greenhouse where the temperature doesn’t get above 70 degrees. They won’t tolerate too much moisture on the roots, so leave off watering until they dry out almost completely, about once a month. Fertilizer isn’t necessary. To get geraniums to fit in the space you have available for storage, pruning is OK. Don’t, however, get too severe. Be sure to leave some leaves and green stems. Be aware they won’t be very attractive as they take a winter break.
The hardiness of fuchsias depends on the cultivar. Many can survive in western Oregon in a protected spot, Edmunds said. Those bought in hanging baskets are usually more tender. If you still have the label, check that for information. Or, if you’re not too attached, an experiment might be in order. Leave the plant out this year, see what happens and keep a record. If it dies, switch to a hardier variety next year that will survive outside.
To keep fuchsias safe from too-cold temperatures, move hanging baskets or pots into a cool spot between 40 to 50 degrees. A cold frame or cool greenhouse will work, and, since fuchsias don’t need as much light as geraniums, a garage or shed will accommodate them. A cool room in the house is fine, too. They’ll want more water than geraniums, so check often to make sure the soil is moist, but not soggy. Pruning isn’t necessary, but will allow plants to be stored closer together. Don’t over prune and cut off all the green wood, however.
“Lots of people treat fuchsias and geraniums like annuals and don’t go through the trouble of bringing them inside,” Edmunds said. “But if you want to baby them a bit, they’ll come back to life in spring.”
Many people dig up dahlias in fall, more because of rot than cold, Edmunds said. Before digging, cut plant down to soil level. Be sure to use the shovel carefully as nicks and scratches will cause them to dry out faster. Wait until spring to separate tubers. Store clumps of dahlia tubers in a dry, dim spot in a cardboard box with plenty of air circulation. Check periodically and remove any tubers showing rot.
In spring, fuchsias and geraniums should be trimmed back, fertilized and moved back outside. Plant dahlia tubers when all threat of frost is over and soil has warmed up to about 60 degrees (use a soil thermometer available at garden stores to check), usually from mid-April through May.