I recently acquired this little 3-inch 'Desert Diamond' agave pup (a strain of Agave potatorum), which I'm keeping as a houseplant for the foreseeable future. It's living with my other two succulents (an aloe and a Christmas cactus) in a warm sunny window, getting the same care, and it's growing (slowly) and looks healthy. I know it's a pretty small and compact type of agave, not supposed to get much bigger than a dinner plate. But just how long could it take to get that size? Can anyone give me a clue as to the average growth rate? As in, how much will it increase in diameter per year?

Agaves tend to be fairly slow if not in their habitat.Potatorum varies in size, but will stay compact. Since you live inland and arround my geographical latitude, im guessing you have to overwinter it....... So in a nutshell, get a more coarse soil, repot, dont water for half a month, and water weekly with a tiny ammount, less often in winter.

The sports of "Kichijokan" (of which "Desert Diamond" is one) tend to be excellent container plants.

Happy Crown Agave (Agave 'Kichijokan')
Agave 'Desert Diamond'
Happy Crown Agave (Agave 'Kissho Kan')

It will grow differently in a container compared to how it grows in the ground (smaller, slower, less prolifically). And the variegated versions of this plant grow slower than the non-variegated form. I doubt anyone will be able to tell you the increase in diameter per year, though. With small agaves that don't have too many leaves (like the one in your picture) you might expect a new leaf a month when they're going strong. Later on, close to full size, it might be more than that. Your plant might reach near its full potential (limited) size after 5-10 years under optimum care, roughly.

The size of the rosette is not something to aim for, necessarily. For example if you provide insufficient light indoors, the leaves may end up getting stretched, and the plant might look bigger overall as a result. But etiolation is not great for the health of the plant and it's something to avoid. Light is always going to be an issue with indoor agaves. To minimize this, keep your plant right in front of your sunny window and make sure it "sees" the sun for hours a day year round. This is particularly important during the shorter, darker days of late fall and early winter, when you should check the situation to make sure the sun is still hitting your plant.

You cannot provide too much light indoors.

skopjecollection said:So in a nutshell, get a more coarse soil, repot, dont water for half a month, and water weekly with a tiny ammount, less often in winter.

It might help to move your plant to a mix with more pumice/perlite/gravel in it, like regular potting soil with an equal volume of rock mixed in. And you should wait to water after repotting for a week, but 2 weeks is overkill. When it comes to watering your indoor succulent "less" than an outdoor plant, that does not mean less water but less often. It means watering to completion (generally, maybe not in the darkest, coldest days of winter) but doing it less often. Not watering your plant to saturation does not do you any good unless you're particularly worried about cold and dark conditions. Cold, dark, and wet is like a lethal trifecta for agaves.

Water well, until water comes out the holes in the bottom of the pot, and then wait until the soil is dry or almost dry at depth before watering again. The actual interval will vary with the weather and the seasons but it will tend to be longer in winter (maybe every 2-3 weeks) than it would be in summer (maybe once a week). Having more rock mixed into the soil will help the soil dry out faster and keep you from overwatering, which may lead to rot complications.

Baja_Costero said:
keep your plant right in front of your sunny window and make sure it "sees" the sun for hours a day year round. This is particularly important during the shorter, darker days of late fall and early winter, when you should check the situation to make sure the sun is still hitting your plant.

Well, it *is* right up against my south-facing window, which is the best light I've got. During the summer months the sun does not hit that window directly, so the plants get a full day of bright but indirect light; in winter it will get a few hours of full direct sun each day. So far, that has been satisfactory for the other two succulents (both have grown like crazy the last few months), so it should be good enough for the agave. I've had it about a month and it's unfurled one new leaf, so your growth estimate is right on so far.

Baja_Costero said:It might help to move your plant to a mix with more pumice/perlite/gravel in it, like regular potting soil with an equal volume of rock mixed in... When it comes to watering your indoor succulent... it means watering to completion (generally) but doing it less often.

It's currently planted in Miracle-Gro's succulent potting mix, same as the other two plants. I do saturate the other two when I water, but because the agave is in a relatively large pot for its size, I'm watering more sparingly for now; if I watered enough to saturate the soil, I'm pretty sure it wouldn't dry out quickly enough.

My bag of Miracle Go cactus mix looks a bit... more ""perlitely," I wonder if you got an odd batch? For my Agaves, I add about 50% perlite to the mix.

Yeah, I would think the mix should be about 50% inorganic, whatever the source. If the bagged MG mix doesn't look "perlitey" enough then I would add some more. Though I prefer pumice, but whatever works for you, given what you have available. Then you can water to saturation without being overly concerned about the soil staying wet for too long. Having a reasonably rocky mix makes care easier.

romalu said:Well, it *is* right up against my south-facing window, which is the best light I've got. During the summer months the sun does not hit that window directly, so the plants get a full day of bright but indirect light; in winter it will get a few hours of full direct sun each day.

That sounds ideal. I have experienced the same thing with one of my southerly facing windows where the sun cuts out at the start of summer. No big deal really. I can tell the difference, but it's over soon enough and all that southerly light in winter is magical for my indoor succulents.

There are other varieties that make good house plants. I just purchased Agave Isthmensis 'Shoji Rajin' Variegata sold as Agave potatorum variegata at Mountain Crest Gardens on line cheaply. It is a Japanese cultivar that stalls small. There's also Agave Schidigera shira ito oh no ohi that doesn't pup and stalls small also purchased at Mountain Crest. These are rare and don't know how long they will be offered. On Ebay they sell for 10 times more.
I find them easier to grow than most of my other plants. Just don't over water. By holding back on the water, they grow more slowly and best during cold low light winters. I have lost some only to over watering.
I do grow some of the large ones as well. A lot of trouble bringing them in every winter in my zone 6 area.