In most parts of the U.S., we only get to enjoy geraniums during the warmer months. It’s pretty clear they aren’t exactly fans of the winter chill! If you want your plants to explode with buds and keep blooming “forever,” you really need to get to know their temperature sweet spots.
Geraniums have African roots
Now, let’s clear up a little plant nerd confusion first. There are hardy, native “true” geraniums (Cranesbill), but the colorful window-box favorites we all call geraniums are actually botanically known as *Pelargoniums*. These beauties originally come from South Africa, where it’s hot and dry. Their DNA is hardwired for those sunny climates—and that’s true even for the plants you buy at your local nursery that have never seen a South African sunset.
Geraniums and freezing temperatures don’t mix
You might see some sources claim that geraniums can handle a quick dip down to 23°F (-5°C), but I wouldn’t bet your garden on it. To be safe, treat your plants as if they have zero frost tolerance. It’s much closer to the truth and will save you some heartbreak!
This means that, unfortunately, geraniums generally can’t overwinter outside in colder climates. But don’t toss them out! They don’t have to be one-season wonders. You can easily overwinter them in a basement or garage. You can keep them right in their flower boxes or even store them bare-root without soil. Just wait until the danger of frost has passed in mid-May before bringing them back out for their summer debut.
The perfect “nap” temperature
When your geraniums are resting for the winter, don’t keep them in a warm room. If it’s too toasty, they’ll start growing thin, spindly “leggy” shoots that won’t produce any flowers. The sweet spot is between 40°F and 50°F (5-10°C); at this temp, they’ll stop growing and just chill out. A good rule of thumb: the warmer the room, the more light they need. However, if you started new plants from cuttings over the summer, they prefer it a bit warmer—around 50°F to 60°F—during the winter.
Ideal temperatures for the growing season
As we mentioned, growth pretty much stalls out below 50°F. To get those vibrant leaves and a long blooming season, you need to crank the heat up a bit. Here’s what they love:
- A very sunny and warm location is key.
- South-facing balconies or patios are perfect.
- The more sun a geranium gets, the more flower buds it will produce.
- The “Goldilocks” temperature range for growth is between 60°F and 77°F (15-25°C).
Quick Tip:
If you collected seeds last fall and want to grow your own geraniums this spring, keep them at a steady 68°F to 72°F (20-22°C) for the best germination.
Take it slow with temperature changes
Whenever you move your geraniums to a new spot—especially when bringing them out of winter storage—make sure to acclimate them gradually. A sudden shock to the system isn’t good for any plant!
