Overwintering tree aeoniums
Aeoniums are beautiful rosette-forming succulents, native mostly to the Canary Islands off the coast of Morocco. They cannot survive winter cold below freezing. Different sources say they’re hardy to 35F/2C, some say more like 25F/-4C.
I’ve been growing them in my garden in Seattle since 2019, and this article will summarize the different ways I’ve overwintered them, with pros and cons mentioned for each. This advice is specifically for those in a maritime climate like the US Pacific Northwest (characterized by rainy winters without a lot of light, lowest lows usually somewhere between zero and 15 degrees) — if you live elsewhere, some of this may be applicable, but you’ll have to read between the lines a bit.
I do not profess to be an aeonium expert. My comments here are based on starting with two rosettes purchased from a nursery in Northern California back in 2019; as of 2025 I have turned those two into perhaps fifty plants. I have had some successes and some failures as well.
Also, this will be describing “tree aeoniums”, aeonium arboreum, as seen in the pictures. I have what I believe to be the straight species, as well as a cultivar called ‘Velour’ that some sources say is aeonium arboreum, and at least one source says is a hybrid of aeonium canariense. Different species with cultivar names such as Kiwi or Sunburst may have slightly different needs (I personally have had less success with them).
I’ll be mentioning 4 basic strategies. From least effort to most (fair warning, I generally get more success with more effort) this includes:
Bring them into your house as a houseplant
Keep them on a covered porch, only bringing them inside when nights are below freezing
Bring them into a dedicated plant setup in your home with plenty of LED lighting
Keep them in a heated greenhouse or cold frame
Aeonium ‘Velour’ is a dark wine red whose center remains green
General aeonium care in zone 8
Before getting into overwintering, here is a quick summary of what to expect from your aeoniums generally, specifically for zone 8 where I live.
People tend to think of succulents as liking baking hot sun and little water. While many do fit that description, aeoniums are a little more moderate in their needs. I wish I could say I’ve been to the Canary Islands to experience their native climate, but it is described as mild year round, with summer highs peaking at 80F/26C and very mild winters, lows around 60F/16C. They are used to dry summers and mildly wet winters. In Seattle or the Pacific Northwest in general, summers match their native climate pretty well, but our winters are colder and much, much wetter. So they will likely enjoy summer here (they’ll want afternoon shade in our hotter microclimates), but need artificial support in the winter.
The other main thing to know is that aeoniums are mostly dormant in the summer, experiencing growth when water is available in fall and winter. In prolonged hot and dry weather, the rosettes can lose quite a few leaves, shrink and curl to preserve moisture. Counterintuitively, with ideal conditions they become lush and huge in the winter. With moderate water in the summer, they’ll continue to resemble their lush winter forms — don’t be afraid to water your aeoniums occasionally in the summer (especially when temps are over 80F/26C, maybe every 10 days to two weeks).
The biggest challenge in growing aeoniums in these parts is having them overwinter successfully. Like many plants that are not native to the Northwest, they resent being wet all winter, and of course our coldest cold snaps are too much for them. So what should you do?
Option 1: Treat your aeonium like a houseplant over winter
By far the lowest amount of effort involves bringing your aeonium inside for the winter. Although you can plant aeoniums in the ground for the summer, by keeping them in pots year round you just move them back and forth between the house and your garden or patio in winter and summer.
However, especially in Seattle, we don’t get a lot of sunlight in the winter, so even in a southern facing window, your aeoniums are likely to sulk. They also like to be moist in winter (remember, that’s when they expect their rainy season) — a heated house with 50% humidity is going to lead to lots of leaf drop in what should be their growing season.
You can certainly go this route; it’s easy and low maintenance. Try misting them daily to increase humidity, give them a drink every month or so when the soil is very dry, and they will likely survive. But we can do better.
Option 2: Keep your aeonium outside but out of the rain
Keeping your pot outside for the winter lets an aeonium experience a nice level of humidity, as long as it’s out of direct rain. They would like as much light as you can provide still, so a covered porch or carport can work really well (NOT a dim shed with just a few small windows). The level of light outside, even under a cover of some sort, is generally a lot higher than your sunniest window sill inside. They will need water if their soil gets very dry, likely no more than once a month.
The extra burden with this option is that you have to move them inside whenever temps will be below freezing. If you only have one or two pots, this may not be a big deal. If there is prolonged cold and they spend weeks inside, you are basically just treating them like a houseplant, and are back to the drawbacks of option 1. The biggest risk of this option is how easy it is to forget about them for just a single night. There’s nothing like waking up in the morning and remembering (too late) that you forgot to bring your tender plants inside on a cold night, and now you have squishy mush where there used to be a beautiful rosette (ask me how I know!).
Option 3: Artificial lighting for your aeonium
If you are a serious plant geek, you may already have some sort of plant station set up in your house, either for growing seedlings or babying plants that want a lot of light. If so, that station would be great for your aeoniums over winter. It doesn’t solve the humidity problem, but increased light really helps. Mist them frequently, and water them thoroughly when the soil is dry, once a month or so.
If you don’t have a plant or seedling station, it’s not hard to set up. I’m not going to go into total detail here (that’s another post, perhaps), but I’ll comment on what I use.
This is my seedling station in my basement
I have a wire shelving setup in my basement (pictured above), it’s 4 feet wide by two feet deep, and six feet tall (here is an example on costco.com). I have four shelves. To create lighting for each shelf, you can attach LED shoplights to the shelf above, using something as simple as zip ties or velcro straps to attach the fixtures. Buy lights that can be daisy-chained together, and you can pretty quickly wire up three or four lights for every shelf in series that are all powered by a single on/off switch. You don’t need to buy super powerful “grow lights”, cheap shop lights work just fine. Here’s an example link on amazon.com.
Keep the lights really close to the plants (unless you did buy fancy grow lights, then you need to research how close they should be). With indoor lights, the falloff in brightness for each inch away from the fixture is enormous — the lights should only be a few inches above your plants. The nice thing about the wire shelving setups is that it’s relatively easy to adjust shelving height for the size of your plants.
Indoor plant lighting solves one of the two limiting factors for having happy aeoniums over winter, which is lack of light. However, they still would really rather be outside, I know because the difference is night and day if you can keep them outside. To achieve that, you’re going to need a greenhouse or a cold frame. Read on!
Option 4: Use a heated greenhouse or cold frame
Wouldn’t it be nice if we all had space and budget for a greenhouse? With plenty of light, coverage from rain, and the ability to be frost free with artificial heating, using a greenhouse is a pretty luxurious way to overwinter aeoniums (as well as pelargoniums and any number of tender plants).
I do not have a greenhouse. Though I can technically afford one, I am hesitant to give up the space in my garden. I also do not love the idea of using electricity to heat one. Folks who are new to greenhouses may think “aren’t they naturally much warmer than the outside ambient temperature?” Yes, during the day, they are, assuming they collect some sunlight (which is no guarantee in the Northwest). But at night, without some serious passive heat engineering, the temperature in a greenhouse pretty quickly gets to be exactly the same as outside, especially when it’s truly cold.
If you do have a greenhouse, and keep it frost free, keeping aeoniums there is easily the best solution.
Given that I do not have a greenhouse, I started using cold frames for my tender plants. (If you’re thinking, “what’s a cold frame?”, here’s a quick Wikipedia entry to give you the basics). Cold frames have a couple of advantages over a greenhouse:
They’re way cheaper and easy to set up
They’re easy to move if you find a better place for it later (or move altogether, or decide you hate overwintering plants and want to sell it!)
Because of the vastly smaller airspace, they’re easier to make frost free
I bought a Juwel-branded cold frame through costco.com. It has twin wall polycarbonate sides and lids, which means it has inherent insulation resembling double pane windows. However, when it’s freezing outside, it’s going to be freezing in the cold frame, so you still have to add some heat.
What I do is run a single strand of incandescent holiday lights (with C9 bulbs, here’s a link to an example set on 1000Bulbs) inside the base of the cold frame. For bonus points, you can buy a pack of stakes to line them up neatly and keep them in place. Even with just a dozen or so lights on, this raises the ambient temperature inside the cold frame by ten or so degrees on cold nights, and is a negligible hit to my energy bill. In a mild winter, this could be all you need. If you want to know what the temperature is inside the cold frame (or your greenhouse), any thermometer will do, but a remote sensor will let you keep tabs on the temperature while you’re warm inside in your jim-jams. Here’s a link to the one I use available on amazon.
If we get a blast of 10F/-12C, a few light bulbs are not quite enough. In truly cold weather, I have had good success by maxing out the lights, covering my cold frame with a fleece blanket (like you would use inside on a bed, not a garden fleece), and then covering the whole thing with a tarp. The blanket adds a big measure of insulation, and the tarp protects the blanket from getting wet and losing its insulating power. The plants won’t mind being in the dark for a few days.
Speaking of being in the dark, using string lights does mean that your aeoniums are going to be mildly lit most of the winter. They don’t seem to care. I think the volume of light is pretty low, though it does turn the cold frame into a gently glowing feature out in the garden, see below!
Here’s one of my cold frames aglow with holiday lights
I generally overwinter some aeoniums in the house, some in my seedling station, and as many as I can out in my three cold frames. The difference is stark — the ones in the cold frame grow significantly, they look lush, and are an utter joy to unpack in the spring. The ones kept indoors stay alive, they just look a little sad and shriveled by comparison. Below are a few pictures of the aeoniums (and a few assorted echeveria and sedums) overwintering in cold frames.
What do you do if your aeoniums have gotten very tall?
Tree aeoniums growing strongly may get to be 12 to 18 inches tall in Seattle, with a few branches each bearing rosettes. In my own experience, if they get any bigger than that, the stems tend to be unable to support the rosettes, and they break. This is not a catastrophic break, as you can re-root the broken stem, as described below.
If your aeonium is too large to bring into the house, or too big for your seedling station or cold frame, you can opt to cut some or all the rosettes off and “restart” them in the fall as you’re bringing them inside. This will result eventually in having several new (but smaller) plants. Like many succulents, aeoniums root easily from a cutting. I find that cutting them in October allows them to establish roots over the winter when they’re ready to grow, and you’ll have plants ready to deal with the heat of summer next season. You cut the stems just an inch or two below the rosettes, and then pop the rosette into soil with the stem serving as an anchor that will eventually root. Most sources advise you to wait several days after cutting to let the stems callous over (to prevent rotting or disease), but I find this is unnecessary.
Parting thoughts and notes
If you made it this far, thanks for reading! I think sheltering a few otherwise tender plants helps make your garden feel more interesting come summer, so I don’t mind fussing with a cold frame setup. However, it’s not for everyone. You can totally just go the houseplant route, and good luck. A cold frame can be used in the summer for seedlings and propagating cuttings, too, I’ll do a separate post on that eventually.
In my climate, I wind up getting the aeoniums into protection around November 1st (our first frost is typically mid-November), and they come back out in late April. So they are going to spend nearly six full months in whatever overwintering scheme you’ve got, and do all of their growth in that time. In the summer, they more or less stay as they look coming out of protection, so baby them as much as you can to maximize how good they look in summer.
You can try planting aeoniums out in the garden during the summer, which is a fun way to feature them (as opposed to just staging them in their pots). Amend the soil with plenty of sand and pumice, and feel free to water occasionally (but not daily or anything). If keeping them in pots, a good potting mix is standard potting soil with the addition of a generous amount of pumice (succulent mix may actually drain too quickly for aeoniums).
Happy planting!
