Overwintering geraniums preserves these tender perennials for the next year. Grown as an annual across much of the US, their brilliant blooms appear to float above the foliage and bright add color to gardens and decks from spring until fall. Favored for their attractive foliage and their ability to withstand the bright summer sun, geraniums adorn porches, window boxes and hanging baskets and range in color from white and pink to brilliant red.
Many gardeners prefer to bring their geranium inside for the winter to preserve their beauty for another year. Overwintering them is easy, as these remarkable plants have the ability to survive for months without soil and only occasional water.
Digging up Geraniums
Dig up geraniums in the fall before they are killed by frost. Shake the plants to remove excess soil from the roots. Your geraniums will be stored bare root and do not require soil.
Hang Geraniums to Overwinter Them
Overwinter your geranium plants by hanging them upside down in a cool, dark area for the winter. Some prefer to place the plants in paper bags, but this is not necessary. An unheated room or attic works well as a storage area, as long as temperatures remain above freezing. An ideal temperature for winter storage of geraniums is between 45 and 50 degrees Fahrenheit, according to Cindy Haynes of The University of Illinois Extension.
Soak the Roots of Overwintering Geraniums
Remove the geraniums and soak the roots in lukewarm water for 1 to 2 hours once every 2 months to keep stems from shriveling. Leaves typically dry and fall off the plant, but as long as the stems are firm and pliable, the plant will survive. Check your overwintering geranium plants once a month for shriveling.
Prepare Soil and Planters for Overwintering Geraniums
Prepare planters or pots for replanting your overwintered geraniums by filling with a mixture of equal parts peat moss and all-purpose potting soil. Peat moss provides organic matter, increase aeration and promotes drainage.
Plant Overwintered Geraniums in Individual Pots
Plant your overwintered geraniums in individual pots in March. Cut off any dead or shriveled stems at this time. Don’t worry if the stem is short, as long as the roots and a portion of the stem is alive the plant will regrow. Water thoroughly until water runs free through the drainage holes.
Place the plants on a sunny windowsill. A southern or western window provides the best light for geraniums. New growth appears within a few weeks.
Apply water-soluble fertilizer when new growth appears. Repeat every two to three weeks, or water weekly with a weakened solution mixed to 1/4 strength. Water when soil is dry to the touch one inch below the surface of the soil.
Return Overwintered Geraniums to the Garden
Replant your geraniums in the garden or move planters outside in late spring once the danger of frost has passed in your area.
By overwintering your geraniums, your plants will grow larger and produce showier blooms each year. Get into the habit of overwintering geraniums inside each year and you will soon be the envy of your neighbors.
University of Illinois Extension: Overwintering Geraniums
Iowa State University Extension: How to Overwinter Geraniums