Overwintering annuals is possible with these tips (2024)

Every autumn, gardeners gaze at some of their beautiful annuals and wish there was some way to save them. Then, every spring, they wish they didn’t have to spend money on the same plants they just discarded the previous fall. Some annuals can be over-wintered to make a Phoenix-like recovery the next season.

Some caveats apply. They will look awful for most of the winter, constantly dropping leaves and getting leggy. Some plants need a lot of light, and some don’t. The procedure changes depending on the annual, with some not working at all.

Saving vines is easy and requires little space. Take 8-inch cuttings of herbaceous vines like Tradescantia, strip off the leaves on the bottom two thirds, and root them in water. Change the water about once a month. In spring, when new growth is actively growing on the tips, do it again, discarding the old vine and rooting the new tips. Plant this new growth once they have rooted. Woody vines can be dug up and potted, treating them as houseplants for the winter. After several years, when the base is too large and woody, start over by rooting some cuttings in water as previously explained.

Large container-grown annuals like geranium, diamond frost euphorbia, and Mandevilla can be saved in two ways. If you have an area of the house that gets a lot of light, like a sunroom, or south-facing room with big windows, you can keep them alive as houseplants. They will be messy, slowly dropping leaves, and have under-sized blooms until the longer days in March. Cut back on the water and do not fertilize until they begin to put out new growth. When that happens, prune them back by a half or more for the new growing season.

The second way keeps them out of the house and requires less maintenance. You can put them in a garage or shed that gets cold but doesn’t freeze, ever. They will over-winter as live but semi-dormant plants. Keep the soil just moist, not letting the potting medium shrink and pull away from the pot edges. In the spring, when other indoor plants are starting to grow, prune them back to 4 to 6 inches. The Mandevilla can remain longer. Start giving them more light until it is safe to move them outside.

After 3 or 4 years, the potting mix of the large annuals will become hard and compacted. In the spring, remove the plant from its container and decide what to do. Either shake off the old soil if you can and repot it using a slightly larger pot and new potting mix or prune the roots and repot it in the same pot with fresh mix.