When it comes to excellent landscape Agaves, the Agave “celsii multicolor” is a popular choice. They reach a moderate, manageable size and are extremely attractive in the garden.
They’re also somewhat uncommon, and typically found as small seedlings in 4″ pots if they’re available at all. On top of that, the species name isn’t even Agave celsii (which is why I’ve called it Agave “celsii multicolor”). Speculation online is that they are likely Agave mitis, or perhaps Agave boldinghiana, but I can’t find anything definitive.
In the book Agaves of Continental North America by Gentryi, he has Agave mitis as a synonym of Agave celsii, so I’ll leave it up to you to decide.
For practical purposes, if you’re looking for information on this stunning plant, looking for Agave celsii multicolor is your best bet.
Planting your Agave celsii
While these can do tolerably well as container plants, for best size and growth, you’ll want to plant yours in-ground.
These thrive the best when provide with well draining soil, and do not care for soggy feet. At worst, thoroughly mix up your soil for about 6 – 12″ around the widest part of your plant, and mix in a bit of supplemental lava rock or pumice to ensure the portion closest to the agave’s root base will be more porous than the surrounding soil. Mine have done well in relatively dense, poor soil that is high in decomposed granite, but I mulch around them every winter.
In a pot, a mix of 25 – 50% pumice or similar inorganic medium mixed with a standard succulent soil is your best bet. The more inorganic material you use, the more often you’ll need to water. If you tend to forget about your potted plants, go with more organic material in your pot and these will do fine. They’re super forgiving.
Watering Agave celsii var. multicolor
These are extremely easy going agaves. As younger plants, you’ll want to water a bit more often during the hotter months to allow them to get established.
When the soil around them is dry, that’s when you water – a thorough drench works best. Here in San Diego, I’ll water mine about once a week during the height of summer, although in a pinch I can stretch it to every two weeks.
One way you can tell that they are in need of water is that the leaves will start to curl together, with the outer edges curving in enough that in extremely thirsty plants, they’ll touch. I usually prefer not to let mine get quite so thirsty, as I think they look best with nice open leaves and robust growth.
In pots, watering is more dependent on your weather and plant. While in-ground plants can go quite a long time, even in summer, with little to no water, a potted plant will rapidly crisp up and die if left without water too long. Your potted agaves should be watered when they’ve been dry for at least a day or two, or even a little longer. By ensuring they get dry all the way through their root ball, you minimize the chance of rot.
In winter when the temperatures drop below 50 at night, you’ll want to cut back on watering almost entirely. In-ground plants can be left almost entirely alone to cope with winter rains, while potted plants should get a light watering only a handful of times over the course of the coldest months. If you’re giving them a bit of supplemental water, be sure that there’s no chance of temperatures below 32F in the week after. While Agave celsii var. multicolor can survive a light frost, its roots should be entirely dry for it to handle the weather best.
Lighting for your Agave
Agaves are a type of plant that really, really should be grown almost entirely outdoors. In colder climates, a heated greenhouse would do the trick during the colder times of year, but these really need nearly full sun for best growth and appearance.
If you have large, south facing windows and have otherwise done well with similar desert plants, you could feasibly try growing these indoors by said windows…but I’m not sure you’d really want agaves inside.
Agave celsii var. multicolor is extremely mild in terms of leaf spines, but the tips are wicked sharp and hurt like an absolute bitch if you get stabbed by one. I’ve been known to accidentally jab a leaf tip into a leg when weeding, and I need to use tweezers to pull out the embedded spine edge.
If you have small children, dogs, or love your spouse, I suggest keeping these outdoors, preferably somewhere that people don’t often have to squeeze by them.
And light. At least 3/4 of their day should be in full sun.
Life cycle of Agave celsii var. multicolor
As with all agaves, this species is monocarpic, meaning that they only bloom once and then are done. The bloom can last a month or more, and often has hundreds of flowers that draw a wide variety of pollinators from miles around.
Interestingly, what I’ve heard of this particular cultivar (which is not found in nature) is that it has a quite short lifespan for an agave. From seedling to blooming plant, the lifespan is supposedly only about 5 to 8 years. I purchased mine as seedlings (maybe 6 – 8 months old?) in winter of 2018, making them around 4 years old. They’re quite large and have not pupped at all, so I’m not sure what to expect.
According to Gentryi in his book Agaves, true Agave celsii form large clumps of plants slightly smaller and with somewhat more slender leaves than my multicolor specimens. He also references clumps at the Huntington Botanical Gardens that are over 40 years old, which naturally is quite a bit longer lived than this cultivar is purported to be.
When they do eventually bloom, these can be expected to produce large bloom stalks and a prolific number of bulbils on the bloom stalk.
If you do not have these in-ground, expect growth to be extremely slow. Mine did not begin to exhibit consistent growth until planted in ground.
They can tolerate a light frost, even hail, but they will show signs of frost bite or other frost damage. Both of my plants had severe scarring after our hail storm in early 2021.
Mature size should be somewhere around 3′ across and 3′ feet tall.
Try not to use a leaf blower directly around them; the dust blowing at high speeds will lightly sandpaper off a layer or three of the leaves, making them a bit less attractive.
You don’t really need to fertilize these, particularly not if you are mulching them in winter like I do. The slow breakdown of the mulch over the year is more than enough additional organic material for them to thrive.