Growing and Overwintering Fuchsia, Geranium, Dahlia and Tuberous Begonia
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Fuchsia, geranium, dahlia and tuberous begonia are perennials that will not overwinter outside in Alaska. These plants are native to much warmer climates. Special care and an indoor overwintering site are required to keep these plants from year to year in Alaska. The extra work does have its rewards; each of these plants have large showy flowers.
General growing requirements
Maintaining a vigorous, healthy plant during the growing season is one of the first requirements necessary to ensure that the plant can survive the long period of rest or dormancy. A perennial plant must be able to produce sufficient growth and food reserves if it is to maintain itself and put forth new growth again the following spring. During the growing season, fertilize weekly with a weak complete soluble fertilizer high in phosphorous such as 15-30-15.
These flowering plants may continue to produce an abundance of flowers until frost stops all further growth and activity. In preparation for the approaching season’s end, you should cease fertilizer applications at least two weeks before you anticipate bringing them indoors. Watering should be reduced to a great extent, but not to the point where the root system will die.
Fuchsia (Fuchsia spp.)
There are more than one hundred species of fuchsia, mainly of perennial trees and shrubs. These plants are all members of the plant family Onagraceae, the evening primrose family.
The fuchsia is very adaptable to much of Alaska’s outdoor growing conditions. It prefers a daytime temperature of 60° to 70°F and a nighttime temperature of 50° to 65°F. The cool night temperatures are especially important during the early growth of the plant, when new growth is pinched and flower buds are developing. It also does very well in filtered sunlight or semi-sunny conditions often associated with locations along buildings where hanging baskets are placed for aesthetic appeal.
A continuous blooming hanging basket of fuchsia provides a great amount of beauty to its surroundings.
To simplify information, trade names of products have been used. No endorsement of named products by the University of Alaska Fairbanks Cooperative Extension Service is intended, nor is criticism implied of similar products that are not mentioned.
The proud owner will often want to have this growth and beauty available from the same plant the following season.
Geranium (Pelargonium sp.)
Garden geranium are not really a geranium but a Pelargonium. They originated from South Africa. Geraniums are a favorite plant for gardeners all over the world. Most plants are propagated from stem cuttings, which easily root in water or moist sand. The seeds are difficult to germinate because of a hard seed coat. Scarification or nicking the seed coat greatly speeds germination.
Overwintering fuchsia and geranium
The contained plant can be overwintered in any dark, cool place that is 40°F and frost-free. The soil must not be allowed to dry out.
Bring the plant indoors before the first frost is expected. Pruning the plant back prior to overwintering will reestablish a centrally located area for new growth. This will result in the formation of a full, compact plant when growth resumes. Remove all the green and red stems, leaving the tan hardwood. Remove all the leaves. Water to keep the plant slightly moist but not wet during the winter.
Early next spring, perhaps as early as mid- to late February, new growth should start appearing. When this happens, increase moisture and return it to the growing conditions the plant prefers (increased light and warmer temperatures). When new growth starts, it will often produce single stem branches. If left to continue, this would result in a sparse, leggy plant. Pinching the growing tips early will promote branching, and the result will be a plant that fills and covers the container.
There are various ways to overwinter geranium. One method is to pull plants from the garden and remove as much soil as possible. Hang the plants in a cool location upside down in a plastic bag with holes and wet peat moss. They can also be left in the pot and treated like fuchsia.
Dahlia (Asteraceae)
Dahlia are an important group of tuberous-rooted plants of the sunflower family Asteraceae. The forms used in gardens today originated from Mexico, Guatemala and Central America. The Spanish travelers brought a handful of tubers back to Madrid in the late 18th century. The Swedish botanist Andreas Dahl, named them. In 1826, English plantsmen had hybridized nearly 60 kinds. Today there are over 1,700 recognized varieties.
Dahlia are among plants that have evolved underground tuberous roots to store food and survive through adverse conditions. The first year a dahlia plant is grown from a seed, it will develop a branched tuberous root system that can be easily overwintered in cool storage. The tuberous root can be replanted whole or split, making several plants. Each one of the tuberous roots attached to part of the stem will produce buds, from which new plants can grow. The buds will be formed at stem end or where the old stem was.
Dahlia thrive best in well-drained soil. They like plenty of water after beginning to bloom but, like roses and peonies, seem to resent “wet feet.”
Tuberous begonia (Begonia tuberhybrida)
Begonia originated in the rain forest in South America. The name "begonia" comes from
Michel Begon (1638–1710) an amateur French botanist who first collected them. These
flowers are grown from tuberous roots. New growth buds appear on the base of the old
stem, at the point where it joins the tuberous root. Begonia like cool, moist, lightly
shaded places where the soil is rich and well supplied with humus.
Flower heads have one large double male flower in the center, with two single female flowers at the sides. Flowering is stimulated by long day lengths, common during the summer in Alaska.
Overwintering dahlia and begonia
Tubers must be dug up and stored before a hard frost. After the weather has begun to turn cool and lightly frosted, lift the tubers. Dig the roots with care, being sure not to cut the roots. A spading fork is the best tool because it is less likely to damage roots. Clean the tubers of soil and let them dry in a dark, well-ventilated place. Do not remove the stems and foliage from the tubers; allow them to dry and fall off. After a week or two, the leaves and stems have withered enough to be removed.
The next step is to put the roots in a container with packing material. This insulates the plant against fluctuating temperatures, retains moisture and reduces disease transmission. Store the tubers in dry, clean peat moss, sawdust or vermiculite and place in a root cellar or similar cool, dark, dry place (40°–45°F) until next spring. A minimum-maximum thermometer can help you locate a good spot. The box should be covered to prevent drying and to keep voles from getting in and eating the bulbs.
Planting tubers
By late March some of the tubers should be sprouting. If not, place them in a warm room and keep them moist and let the sprouts appear. Plant the tubers when buds or eyes appear on the tubers in the early spring. Begin the roots indoors seven to eight weeks before the last frost, about April 1 for most Alaska locations.
Plant tubers in a loose mixture, deep enough to cover the sprouting tip. After shoots begin to stretch above the soil prominently, add an additional two inches of soil to cover the tubers. Give as much light as possible and cool growing conditions (55°–65°F) to avoid spindliness.
Hardening off all plants
Plants grown indoors need to be hardened off slowly to adjust them to cooler temperatures, ultraviolet light, and wind. Do this by placing the growing plants outside during the day starting around the second week of May. The first day put the plants out one to two hours and increase by an hour each day until they are ready to be transplanted outside. After the last frost, move the containers outside or plant in the garden.
Tuber propagation
Cut tubers into segments after the eyes begin to develop in early spring. Each section or tuber should have a developing bud. Use a sharp knife to make a clean cut. If you are concerned about disease, dust the bulb with a registered fungicide.
Stem cuttings
Wait until the plant has strong growth in the spring. Cut a stem several inches long and insert into a moist rooting medium, such as sand, peat moss, sterilized soil, perlite or vermiculite. The new plant will be identical to the parent.
Growing from seed
The seed should be started in early February. Growing from seed provides many plants at a minimum of expense. Plant seeds in flats filled with moist seedling media and place in a warm place. After germination, place under growing lights. Seeds may take up to two weeks to germinate.
These perennials can become part of your life for many years with a little extra effort. Knowing that you can overwinter and bring them back next year allows you to look forward to the same beauty again and again.
Meriam Karlsson, Professor of Horticulture, Institute of Agriculture, Natural Resources and Extension. Originally prepared by Wayne Vandre, former Extension Horticulture Specialist.
Revised March 2021