Hedera canariensis (Algerian ivy) is a lot like its close relative Hedera helix (English ivy), and has most of the same qualities, both good and bad. The most obvious difference is that it has much larger leaves than H. helix, but there are a few other differences as well.
When you do a search for this plant, most of the sites that come up involve outdoor cultivation. It's apparently pretty low-maintenance, and hardy in a lot of places (there's disagreement about the exact range possible: everybody agrees it will grow in zones 8 and up, and everybody agrees it will die in 5b or below, but anywhere between 6a and 7b is debatable, I guess. Also variegated varieties are said to be less cold-tolerant.), and it's pretty pollution- and salt-tolerant, I guess, as well. Also people usually note that it's from northwest Africa (also Portugal and the Canary Islands -- hence the name -- and that general region).
And then tucked in there somewhere will be a one-sentence acknowledgment that, oh yeah, it can be grown indoors too, which is usually as much information as you get.
I bought one in February 2007, and we actually got along pretty well for quite a while. I was a little worried about it, because of how plants in the Araliaceae are susceptible to spider mites, and I was, at the time, already dealing with a mite-y Hedera helix. But it turned out to be okay, even after the H. helix succumbed (to either the spider mites or to my efforts to rid it of spider mites; it's a toss-up which was the bigger problem), and everything was good for several months.
Then I started working in the greenhouse, in August, and shortly there were a lot more plants coming home with me, and things got a little crazy. Less time spent caring for the plants, or even looking at them, and then the blog started in October and things were even crazier. It wasn't a good time to be one of my plants (unless you were new). And at some point around mid-October, I noticed that the Hedera canariensis was looking a little off, a little dusty, but I looked at it a couple times and didn't see any mites or webbing or anything, so I figured it was probably dry (even though the soil was staying wetter than usual, if anything), watered it, and went on.
So by the time I noticed the actual spider mite infestation, it was too far gone to bother trying to save, which is how I learned the valuable lesson that even if it's subtle, a plant that appears to be going downhill is doing so for a reason, and you ignore the early signals at your own expense. If the leaves are not as glossy, if the stems droop a little more than usual, if the color's half a shade off, if the new growth is coming in a little twisted or discolored, there's something going on. Look into it.
(I also learned the lesson that I don't want to buy any more Hederas, though that one I had already kind of suspected.)
Still. H. canariensis is better than H. helix in a number of respects. They do, despite the fate of my own plant, resist spider mites better, and they also seem to be a little less hysterical if they get a little too dry or too wet. I still like them. I might even let myself get another at some point (as opposed to H. helix, which is strictly off the list, forever).
As far as care information goes, well, I couldn't find any reference sources, so all I've got for you is my personal experience, the growers' guide (which is far more concerned about Hedera helix) and some educated guessing. Some skepticism is advised.1
Light: Indoors, bright indirect light seems to be ideal. My own plant, when I had it, also got some filtered sun once in a while. Solid green varieties might tolerate a bit less light, but I don't recommend it.
Water: Though the plant will tolerate a range of moisture levels, it's important to keep this fairly consistent, and never let the plant get completely dry or it will drop leaves. My six-inch pot seemed to be happiest when I watered as soon as it was dry an inch or two below the surface. It generally recovered from getting drier than that, but leaf tips would brown sometimes.
Humidity: The plant itself will tolerate dry air fairly well, but it has its limits, so don't ask it to handle central heating without a little help. More importantly, low humidity will give aid and comfort to the spider mites, if there are spider mites, and you do not want that.
Temperature: Generally not a consideration indoors; the species will survive temperatures down to 15ºF (-9ºC), though it will defoliate and/or discolor if it gets that cold (see Bunnies! Bunnies! It must be bunnies!2 for discoloration pictures). I couldn't find any guidelines for how low it can go before it discolors, but the growers' guide says not to go below 45ºF (7ºC), to maintain continuous growth, and I would be inclined to draw the line a little warmer than that, like maybe 50ºF (10ºC).
Propagation: One of the few really solidly excellent things about Hedera spp. is how easy they are to propagate. Tip cuttings, like one would use for a lot of plants, will work very well, but at work we've also propagated them, in the middle of winter, from single-leaf cuttings.3 For best results, keep cuttings in a warm, bright spot, with extra humidity if you've got it (e.g. a mini-greenhouse sort of arrangement would be helpful) and don't let them dry out: something should be visible within three or four weeks, if I'm remembering correctly.
Pests: Hedera species are very susceptible to spider mites, if slightly less so than H. helix.
Feeding: Hedera is somewhat sensitive to fertilizer build-up, so the growers' guide says to be sure to flush the soil often and avoid getting fertilizer directly on the leaves. Otherwise, feed as for any plant.
Grooming: Mostly limited to the removal of the occasional dead leaf. Vines that grow too long may be cut back; new growth will emerge from near the cut. It may help the plant's appearance to plant cuttings in the pot to keep the plant looking full, though I don't find this to be a huge issue with the plants at work, and when I tried to stick cuttings in with the parent plant at home, they usually didn't take; cuttings seem to need their own space. Plants can also be grown as climbers, though this seems not to be done indoors very often; not sure why.
There aren't as many cultivars of H. canariensis as there are of H. helix, but there still are quite a few. 'Gloire de Marengo,' the gray and white one pictured above, is one of the more common ones, and one also sees quite a bit of the plain green. We were offered a variety called 'Neon' at work, and bought some, and were extremely disappointed: the only special thing about 'Neon' is that new growth comes in bright yellow and then quickly turns green. I suppose this is slightly more interesting than a plant that's all-green, all the time, but not by much.4 As with H. helix, variegation patterns are said not to be incredibly stable, and sometimes plants will switch to other patterns, or revert to all-green (the latter is especially common if the plants are being grown without enough light), though I can't say I've seen this personally.
I suppose calling this one "Ghost" is a little bit of a stretch, though it does meet the one mandatory spook requirement, being dead. At least my own plant is. It also has one more ghosty thing going for it, which is that it haunts places: outdoors, it's got tendencies (like H. helix) toward being an invasive, noxious weed, and it's apparently difficult to eradicate from a given spot once it's become established there. The same easy propagatability that is so desirable indoors is a liability outdoors. As far as I could find, there are no major problems with this species yet, though it is reported to be invasive in small areas in California (the San Francisco Bay area, specifically), and it's on the noxious weeds lists for Oregon and Washington. Florida and Hawaii, who normally get all the good invasives, weren't mentioned in anything I looked at, which is very unusual: my intuition says that it's not that Hedera canariensis couldn't be invasive in those states, it's just that there are so many other invasive species there that it has a tough time building a base of operations. Though my intuition is not incredibly reliable.
They're also slightly hostile to the living, as ghosts sometimes are: like Hedera helix yet again, plants are poisonous, and in extremely good conditions, plants may flower and produce small, shiny black berries, which are also poisonous. Some people experience skin irritation after contact with the sap. I've never had any firsthand (or even secondhand) experience with this, but everybody says it so I figure it must be worth passing along.
So, all in all, how does it rate? Should you get one? Ennh. I don't consider it a plant that everybody needs to have, for sure. If you feel like you really need a plant that looks sort of like English ivy, this one is the best I've found so far: Hedera helix is a less attractive plant (in my opinion) even when healthy, and it's very often not healthy, and the only other option I have any personal experience with is Senecio macroglossus, which didn't blow me away with its great communication skills.5 Hedera canariensis is at least better than those two, I think.
Photo credits: all my own pictures, mostly not my own plants.
1 Really, some skepticism is always advised. Just, more so than usual in this case.
2 Oddly, "Bunnies! . . ." is one of my more popular posts, at least as assessed by the number of Picks it received at Blotanical. I know it isn't my best work, so I have to assume that the number of Picks is related to something other than the quality of the post. I just haven't been able to crack exactly what that critical something is, except to be fairly sure that there's a pro-outdoor-plant bias. Which is not surprising to me (anymore).
3 Which is to say, a piece of stem including a leaf and the node it's attached to: If the node is under the soil, the piece will root and sprout a new growing tip in about eight out of ten cases, even if you don't know what you're doing and aren't trying particularly hard.
4 (Though we did sell out of them, so I guess that's something. Considering how many very cool things we get in that nobody wants to buy -- er, nobody except me and WCW, that is -- I do have to grudgingly acknowledge that it's the Tradescantia zebrina, Codiaeum variegatum, Ficus elastica, Crassula ovata, Spathiphyllum spp. and Dracaena marginata that pay the bills. Hedera canariensis does, if nothing else, pay its own way. So I'll give it that much respect.)
5 Though I have to give it props for being a lot more pest-resistant. I never really got to the point where I could water it the way it wanted, but I didn't have bug problems.