Before the rush of planting the tender annuals in late May, we can use the time to look to the care of any perennials that need dividing and transplanting now. This includes all the late summer and fall flowering ones. Spring and early summer bloomers will be done in late August and early September.
One other category that can be transplanted now are some of the early-flowering bulbs that are best transplanted "in the green." That means after the flowering is over and while the leaves are growing on, snowdrops, daffodils and winter aconites can be successfully transplanted.
These groups are best done this way if the clumps are getting overgrown and are not flowering as well as before, or just because there's another place that would be brightened by their presence.
This is also a good way to have more of your favourite bulbs spread throughout the garden.
Right now is a good time to do the snowdrops and winter aconites because they finished blooming by the end of March or so.
The technique is easy enough to do; it just takes a little care. First add some compost to the new area and have it well turned into the top 20 cm. Have some liquid transplant fertilizer mixed -- no more than half-strength -- on hand. This is the fertilizer with the high middle number (something like 15-30-15 is what I use).
Now, take a flat-edged spade and drive it straight down around the clump about 8 cm away from the leaves. Make sure you go down deeply because, at this time of year, we need the roots that are growing from the bulbs, too; they are vital. These are live growing plants we are dealing with, not the dormant bulbs of fall planting.
It is fine to take just part of a clump and leave the rest in place. Fill in the hole with some nice compost to give the remaining part of the clump a boost. Keep as much soil as possible around the root ball. This will lessen transplant shock. Pop it into the new hole which should be at least twice as wide as the ball but only just as deep.
With the plant in the hole, fill it up with the liquid fertilizer (use water if there's no fertilizer available at the moment), then push the soil in around the plant as the liquid begins to drain away.
This does two things. It gets the moisture down to the roots where it's needed and, as the liquid drains away, it pulls the soil in around the roots driving out air pockets.
Come late May, a nice spreading annual can be placed nearby to cover the fading foliage and add colour for the rest of the season.
For perennials, the transplanting routine is much the same. Done this way, there's rarely any failures, provided the transplant is in good condition. It's usually asters and garden phlox that need attention every two or three years to maintain their vigour. It's easy to tell because the centre of the clump dies out while there is new growth around the outside.
Most directions call for levering the whole clump out, then cutting away the good stuff into as many sections as needed and composting the rest. This is fine but you may not feel the whole thing has to come up just yet, especially with phlox.
If the clump hasn't reached the stage of a completely dead centre then thin out the thin, spindly shoots leaving the sturdy ones to grow on. Top dress and mulch around it, and it will do fine for the season. Sometimes a clump of phlox can be kept going this way for quite a while.
Chrysanthemums can be handled this way as well if time is tight in the garden.
The asters don't lend themselves to this treatment. They have to be dug up separated into nice-sized pieces, then replanted. Chop the old bits up into smaller pieces for compost.
Once the transplanting and other work is done in a section, give the whole area a nice mulch of compost mixed with manure for the rest of the growing season.
My choice is sheep manure because the cow manure often has viable weed seeds in it that can cause trouble later. The sheep's digestive system destroys the weed seeds' viability as they pass through.
Isn't it lovely the things you learn in a gardening column?
