Q. How can I keep my geraniums over the winter? They’re especially gorgeous this year and I’d like to preserve them for next summer.
A. I’ve overwintered geraniums a couple of different ways.
Most years, I cut our geraniums back to a height of two to four inches and repot anywhere from six to a dozen plants close together in large, clay pots in early to mid-October, at left. I then set them in our dining room window where they receive bright morning light, but then only very limited light reflected off of our neighbor's home in the afternoon, below at right.
Since we don’t use the dining room often, the temperature stays around 50°F (or possibly a little cooler) at night and doesn’t go much above 60°F, if that, during the day. I water the plants only when the soil surface feels almost dry to the touch and I don't apply any fertilizer.
By mid-winter most of the plants will have pushed out new growth and sometimes by early spring, a few will even have a couple of flowers!
To encourage additional growth, I've sometimes set the pots outside on sunny, warm days in March and April to soak up as much sunlight as possible. And then, as the chance of frost passes in May, they go out on our front steps for the remainder of the summer.
Meanwhile, a number of years ago I used several geraniums for a demonstration on "Garden Journeys.” After the show I brought them home and set them in our cool (45°F-55°F), damp basement with every intention of cutting them back, repotting them and setting them in our dining room window for the winter.
Well, winter passed - as did much of the spring - before my wife asked if the dead-looking geraniums in the basement where, in fact, dead! Sensing the wrath I might face if I admitted to killing more plants, I suggested that, despite their appearance, traces of life may still exist within the plants, at left.
Taking matters into her own hands, Beth cut the plants back, repotted them and set them outside where they’d receive direct sun all day long. Within a couple of weeks, small green shoots miraculously appeared up and down the stubby stems of the geraniums that I'd neglected for months. And, by mid-summer, the plants where blooming like crazy!
Interpreting these experiences, I would say the key to keeping geraniums from one year to the next involves several things.
If you want to keep your plants growing over the winter months cool temperatures at night (45°F-55°F) are very important. It's also important to keep your plants just a little on the dry side - and do not fertilize them until April. And, the more bright light you can give them during the day, the better.
If, on the other hand, you simply want to get them through the winter, you'll want to store them in stone-lined basement/root cellar-like conditions (dark, 35°F to 45°F and damp) until bringing them out to resume growth in late March or early April.