One cool fall afternoon I pulled two plants from the window box. One was a lavender ivy geranium, the other a trailing red Balcon-type. I carried both to a bright, cool spare room before the first frost hit. That move is the whole answer. Overwintering ivy geranium is just this: get the plant under shelter before frost. Then you pick one of two proven ways. You can grow it on as a houseplant, or let it go dormant in storage.
The reason you have to do any of this is simple. Ivy geranium is hardy only in zones 9 or 10 through 11. A real winter freeze kills it outright. Anywhere colder than that, your plant is a tender perennial you have to rescue each fall. Keeping an ivy geranium indoors winter long is your most reliable way to save a variety you love. I always bring my best two or three plants in and let the rest go.
The houseplant route keeps your plant awake and growing through the cold months. Set it in your brightest, coolest window, ideally one facing south or west. Aim for a room around 55 to 65°F (13 to 18°C). Too much heat makes the stems stretch thin and weak. Water only when the top inch of soil feels dry. Indoors that might be once every week or two. Your plant rests in low light, so it needs far less water than it drank outside all summer. Skip the fertilizer until spring, when you see fresh new growth start.
The dormant route stores the plant cool, dark, and almost dry. Cut the stems back hard, down to about a third of their size, then lift the whole plant from its pot. Shake off the loose soil. Set the plant in a paper bag or a box near 45 to 50°F (7 to 10°C). An unheated basement or garage that never freezes works well. Check it once a month. If the stems feel like they are shriveling, mist the roots or give a small splash of water. You want just enough to keep them from drying to a crisp, not enough to wake them up or rot them.
Watch for trouble on the indoor plants. Whitefly loves the warm dry air of a heated home and will swarm the undersides of leaves. Check those undersides every week or so. Rinse the plant in the sink or spray it down at the first sign of the tiny white flecks. A weak insecticidal soap helps if a colony takes hold. Catching them early saves you a real headache by midwinter, when a bad outbreak can spread to your other indoor plants fast.
Take ivy geranium cuttings in late summer as cheap insurance against losing the parent plant. When you are overwintering ivy geranium plants, this is the easy part. Snip a few healthy stem tips about four inches long, strip the lower leaves, and push them into damp perlite. They root in two to three weeks on your warm windowsill. You get fresh young plants even if the stored parent does not pull through. I keep a tray of these going every year, and the rooted tips have bailed me out more than once.
Move the plant back outside only after your last spring frost has passed. Ease it into the light over a week or so, starting in shade and adding sun a bit at a time, or the leaves will scorch. Prune off any thin, pale growth from its time inside. Give it a first dose of fertilizer once it settles. With that gradual handoff, your saved plant fills out fast and trails over the box again by early summer.
Read the full article: Ivy Geranium Care: Grow Trailing Blooms
