Harden Off Houseplants for Their Summer Vacation

When warm days—and especially warmer evenings—finally arrive, our houseplants are more than ready to move outside. It’s easy to tell. They look a little leggy and droopy. And although I said they are ready for a summer vacation, in reality, they’re taking an eight or nine month winter vacation inside. Because plants grow naturally outdoors, of course!

Geranium hardening off outside.
Geraniums are annuals in our climate, but I love how they bloom indoors in sunny windows all winter.

I really only have geraniums (Pelargonium spp.) right now, along with one canna that I keep in a huge container. It’s my ode to the tropics, and although it hasn’t bloomed again, I love it purely for the leaves. This year, I plan to cut it back and divide it, giving a few bulbs to family members who live in a warmer climate. Maybe dividing and cutting it back will force energy into blooming. We’ll see!

tropicanna canna
This Tropicanna canna is from Tessalaar Plants, and would have trouble making it here, plus uses too much water. But I have kept it alive in a container purely for the leaves. The flower is bright orange and gorgeous!

One reason I have few house plants is time, another is water savings, and most of all, it is lack of space and containers. My succulent-collecting husband has taken up most of the sunny space with propagation, and used lots of the containers. But I enjoy his cactus habit!

The main point to remember when bringing all of your houseplants out for the first time after their “winter vacation” is to introduce them slowly to the outdoor climate again. For most houseplants, that means bringing them into a shady, protected area first or leaving them out on a relatively calm but cloudy day. And bring them back in the first few nights if there is any chance that temperatures will approach frost.

aloe vera plants
Aloe vera plants harden off on a partly sunny day in preparation for the summer outside.

The cacti may be able to sit in full sun from the start; in fact, they probably need it. But if it gets blazing hot, bring them in before day’s end, and don’t subject them to cool desert evenings until they’ve at least been outside through dinner hour. If you don’t want to make the indoor/outdoor trek every night, you can cover your most sensitive plants with landscape fabric until they harden off and the nights warm up. The fabric also can help shade them during the hottest part of the day if temperatures shift while your plants are acclimating.

Make sure your plants are healthy and ready for the move outdoors. I cut my geraniums back quite a bit and usually add a little bit of soil or compost to the pot. If they’re in really bad shape, I will repot them. But they tend to bloom better if slightly root bound. Then I give them a good drink and put them in dappled or partial shade the first few days, gradually giving them a little more sun.

geraniums cut back for hardening off
I cut these geraniums back severely and added some compost, because they did not fare as well as my others. They need repotting next year. Note the requisite gardening gloves and phone…

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