Sometimes the best source of new plants is your own yard! Right now is a good time to divide perennials that have become crowded, and turn them into lots of new plants. Conventional wisdom says to divide perennials in the fall, giving the roots a chance to establish in the warm autumn soil and through winter rain. I've found, however, that because our soil is so dry in the fall, the plants move much more easily this time of year. The soil is softer, and wet enough that I don't have to worry about daily watering of newly transplanted babies.
As I was writing this, my mother-in-law reminded me that many gardeners don't feel confident identifying a perennial in order to divide it. Here's the deal:
Perennials are those plants that live for many years, as compared to annuals that grow, make flowers, and then die all in the same year. Most plants that are bigger than just a little sprout at this time of year are perennials. And if it's something you remember being in that same spot for a few years, it's likely a perennial. (Because it's horticulture, there are of course lots of exceptions: perennials that die back each year, annuals that regrow from seed so easily that it seems as if the same plant is always in the same spot, biennials that die after 2 years, etc, but those aren't important for this post.)
A perennial that wants dividing looks crowded. The stems are starting to bunch tightly together, and it's dense around the base, like the agave pictured below. I think this one is about 7 or 8 years old, and has been getting denser every year. It's a jumble of stems and leaves fighting each other for space.
Dividing agaves, like other large succulents, is physically demanding, but horticulturally easy. Because they'll regrow roots from their stems, like giant cuttings, you can just saw them apart. Usually as you get into pulling the clump apart, you'll find that many of the stems are already sprouting roots into the air, looking for soil. Like all succulents, it's a good idea to let the cuts callus over before planting them, to discourage rotting. I like to leave them out in the sun for a day or two until I can see that the cut has a dry surface over it.
I pulled out and divided just one crowded agave in order to make room for new trees we're planning to plant, and ended up with a TON of new plants, enough to cover the sloping bank in our front yard and still give away about a dozen. (There's also an aloe, the smaller pinker ones in the front, that I divided and planted there too.)
I also divided a huge phormium and planted it in several smaller chunks above the agaves and aloes to hopefully (once they've grown in) block the view of our neighbor's garbage cans.
Dividing a phormium is a different procedure from a succulent. You need to keep the roots attached to the plant! To divide it, first dig around the base to loosen the plant, keeping as much of the root ball intact as you can. Then have a look for where the plant naturally divides itself. Usually there will be multiple stems, or multiple discrete bunches of leaves. You want to separate along those natural divisions. With a smaller plant, you can often tease apart the sections by hand, just by pulling. For larger ones, you can drive your shovel between the sections and force the chunks apart.
The number of new plant chunks you get depends on how crowded the old plant was. My phormium was huge and jammed together, and I ended up with 8 new plantlets. I planted them in several groupings in places where I'm hoping to block views in our front yard with their upright spiky foliage.
With phormiums, and most perennials you'll be dividing, you want to plant them as soon as you can to prevent the roots drying out. With mine, I divided and then planted all in one go. As with all new planting, water them in well, and keep them watered until they're established.
I cut all the top growth off the plants when I transplanted them to take the stress off the roots. This way the roots have a chance to grow a bit more before they have to support the water needs of the plant's leaves. It's remarkable to see how much the transplanted bit has grown since I planted it 10 days ago! The leaves were cut straight across the top, but now the middle leaves have grown a couple inches at least!
This weekend looks to be lovely weather, and a great time to "get stuck in" (as British gardeners say) to some proper heavy-duty moving plants around.
If you're looking for an indoors-y gardening activity this weekend, it's also a good time to work on your garden plan for the upcoming year. What vegetables would you like to grow? Are there annual flowers you'd like to try? Where are sunny spots? The shady ones? Where is wet, and where is dry? You may want to work on the structure of your garden, planning the evergreen shrubs, hedges and trees to frame (or block) views. Before the summer growth fills in, it's a great time to take stock of the garden and calmly plan ahead.
With your plan in hand, it's much easier to grow your annual flowers and veggies from seed because you'll know now what you'll want in a few months! A few hours planning your now could save you hundreds of dollars in plants! Seed starting takes a bit of thinking ahead, but makes a big difference in your garden budget.