How to Overwinter Geraniums: 5 Pro Tips

Geraniums, easy care and long-lasting, bring color all summer and into fall. As we approach cooler weather in fall and even the first frost, we can decide whether to overwinter geraniums or retire them to the compost pile after a hard freeze.

Geranium classifications in the Pelargonium genus include common garden geraniums, ivy-leaved geraniums, and scented geraniums. They all feature distinct leaves with interesting shapes and patterns. 

Common garden geraniums, or zonal geraniums, have large bloom clusters in saturated colors on stiff stems. Ivy-leaf geraniums trail with lobed leaves, while scented geraniums bear notable fragrances in lemon, rose, and cinnamon, among others.

To preserve special selections for the next growing season, it’s worth giving overwintering a try. With three ways to protect the tender specimens, the process is easy.

Overwintering Geraniums

Tender geraniums are mostly native to southern Africa and perennialize in frost-free zones 9-12. For most of us, they’re annuals (though they may survive in lower zones with heavy mulch).

Pelargoniums differ from true geraniums of the Geranium genus. Hardy geraniums, or cranesbill, are tough perennials with billowy foliage and delicate flowers in rich colors. They include native woodland species and cold-hardy performers.

To overwinter geraniums, plan to protect them before the first hard freeze and when nighttime temperatures drop below 45°F (7°C). They overwinter indoors, store as bare root specimens, and are propagated as cuttings.

Prepare and Prune

Stop fertilizing the tender perennials by October as the plant enters dormancy. To prepare geraniums for overwintering, cut back stems by one-third to one-half to reduce the leafy upper growth. This allows the plant to focus on root development.

To overwinter geraniums in the ground, dig them up and either gently loosen and shake excess soil from the roots, or place them in a fitting container. To treat them as houseplants, a container with well-draining soil works well. For bare root, keep them mostly soil-free to proceed with storing.

Bring Them Indoors

An easy way to overwinter geraniums is to bring them inside when the weather cools. Simply give them a trim, water well, and bring the pots indoors. 

To soften the transition from outdoors, meeting their proper light and temperature, and watering requirements are the key factors. Geraniums grow well as houseplants in a bright spot and with average temperatures.

Lighting

Situate the new houseplants in a sunny spot or near a bright window. East-facing windows capture the morning sun, or a south or west-facing position offers the most light on short winter days. Place pots slightly away from the south or west light or filtered with a curtain if the afternoon rays prove too intense.

With lighting changes, plants may become leggy and paler green. Pinch back long or thin stems to just above a healthy leaf node to encourage a bushy form. Leaf color and vigor return during the active growing season.

Temperatures

Geraniums overwintering indoors benefit from cool temperatures between 60 and 65°F (16-18°C). Place pots in a cool room or near a window to lower the temperature.

Keep them away from heated or cooled drafts. Heating and air vents, open windows, space heaters, and fireplaces cause sweeping fluctuations of dry air.

Watering

With naturally slowing growth, Pelargonium needs little watering in the cool season. Roots aren’t absorbing moisture or nutrients as readily as during the growing season. Water only when the soil feels dry to the touch, likely once a month. The pot will feel lighter in addition to dry surface soil.

Check soil moisture every few weeks so roots don’t dry out completely. Overwatering results in roots sitting for prolonged periods in soggy situations, and fungal problems like root rot can develop.

Use tepid or lukewarm water at each session to promote humidity and avoid shocking the roots. Water deeply until it flows from the pot’s drainage holes. Empty trays or saucers after pots have time to drain to avoid letting pots sit in water for extended periods.

Take Cuttings

Fall cuttings are a good option for housing smaller specimens over the winter. And, they offer a jump start on new selections for moving to the garden in spring (or growing year-round as a houseplant).

It’s best to take geranium cuttings in late spring or early summer before flowering, but it’s possible to take them anytime, even later in the season. New, healthy, soft growth is best.

Plan to root the cuttings in water or potting soil, growing them out in pots before transitioning them outdoors in warming conditions.

Pelargonium propagate easily from cuttings. To take stem cuttings:

• Cut a three-to-four-inch piece of stem from a healthy branch, preferably unflowering or with flowers removed.
• Remove leaves from the bottom ⅔ of the cutting, leaving at least two intact. Keep the cuttings moist until ready to pot.
• Optionally, dip the lower portion of the stem in rooting hormone, coating generously. Tap off any excess rooting powder.
• Plant the cutting in at least two inches of moist, well-draining potting mix, coarse sand, vermiculite, or perlite, or in a shallow glass jar with water.
• Place the pot in a bright, warm location, avoiding direct sunlight
• Water as needed to maintain evenly moist soil.
• After about six to eight weeks, when the cutting resists a gentle tug, roots are in place and ready to be repotted.
• Bump the cuttings up to four-inch pots, keeping them indoors in a bright spot, like a sunny windowsill, and moving them outside in mild conditions. Pinch back leggy or spindly tips to promote a bushing habit. New plants will be tender.

Storing Bare Root

An unheated, dry space like a root cellar, basement, shed, greenhouse, or garage is another excellent option to overwinter geraniums. To store them in a protected shelter, plan to house them as bare-root specimens.

Carefully shake most of the soil loose from the roots, whether lifting from pots or in the ground. Removing geraniums from their soil and storing them bare root may be the most challenging method. Take cuttings if the selections are special to cover your bases.

Hang the pruned plants upside down, or place one or two in a cardboard box or paper bag kept open for ventilation. Aim to keep the temperature range between 45 and 55°F (7-13°C) for the best overwintering in a dormant state.

During the season, soak the roots two or three times for an hour or two at a time. Then, return them to hanging, bagged, or boxed storage. Leaves will likely dry, shrivel, and drop, though stems should remain firm and solid.

Ready for Spring

To move the flowering annuals out in the spring, do so gradually to get them acclimated to life outside again. After the final frost, move them to a partially shaded spot for several hours a day, returning them inside in the evenings for up to a week.

Once outside for the season, be mindful of lingering chilly nights that accompany warming days. Bring them in on cool nights.