A Time For Planting And Re-Planting

This week, we continue with the theme that fall is, indeed, a time for planting but, in these cases, it’s also a time for transplanting and replanting. Plants, from the tallest trees to tiny succulents, have finished their above-ground growing season, and now their attention, or energies, are focused on new and expanded root systems.

First, some broad rules of thumb, then a few specifics for how you can divide and multiply some important perennials.

The first rule applies to trees and shrubs. And while there are quite a few exceptions, once a woody plant starts to drop its foliage, that’s a good time to transplant or plant. This isn’t a rigid rule and, in fact, some trees and shrubs do better when moved in the spring, so do your research before you dig.

As for perennials, the rule is that if it flowers in the summer, move it in the spring. And if it flowers in the spring, move it in the late summer.

And, yes, there are exceptions here as well. Daylilies can be moved just about anytime and they seem to survive. Primulas can be moved once they have stopped flowering, but the best time is early spring or late summer, especially when it’s damp. And, of course, there are those trees, shrubs and perennials that are said to “resent” being moved no matter the season.

When it comes to the bulb-type lilies, as in the Asiatics, trumpets or Orienpet types, you’ll read that they can be planted in the spring or fall. Well … kind of, sort of. If you buy from a vendor that has stored these bulbs over winter in refrigerated storage then you can buy them in the spring and plant them.

My experience over the past four years, however, shows it’s not a great idea. These bulbs, just like our other plants noted above, prefer to get their root systems established in the cool late summer and into the fall. When planted in the spring, they expend their stored resources establishing roots when they should be sending up shoots. As a result, they flower out of sequence, and it can take two more years for them to get back on track.

These bulbs need to be ordered in the summer for October delivery and planting, or seek them out at garden centers later this month and into October.

Tall garden phlox, or Phlox paniculata, can be divided and transplanted in the fall, but not quite yet. Let these late-flowering perennials finish flowering, cut the spent buds so they don’t try to set seed, and wait until the foliage drops.

Once the leaves begin to fall, you can reduce the stems to just an inch or so and easily dig the plant and move it with a rounded garden shovel. Better yet, if the plant is several years old, you can take a spade and, before you dig the phlox, divide the parent plant by pushing the spade straight down into the ground to quarter the crown. Then dig the crown with your rounded shovel and transplant the quarters where you’d like them.

Another method allows you to get dozens of new plants from one phlox crown—but you do half the work this year and the other half next year. As soon as the leaves drop, reduce the stems to about a half inch. Take a sharp, round bulb planter and push it, hard, right into the center of the crown, until the bulb planter gets 6 to 8 inches into the ground. That’s it, for now.

In the spring, you’ll get scores of new shoots emerging, and each one can be dug up and transplanted. Each one will be identical to the parent plant, but it will take another year to flower. But, hey, you just made a couple of dozen new phlox plants from the single one you bought a few years ago. Those are great garden dividends.

I’ve really enjoyed the new Geum Totally Tangerine, and I plant more every year. It starts to flower in late May and, if deadheaded, will continue all summer. These can easily be divided now using a tool like a Hori Hori or a long, sharp knife.

If you look at the plant carefully, you’ll see where the crown can be naturally divided, and the knife is used to separate the divisions and lift them. This kind of work is best done on a cloudy or misty day, as it reduces the stress on the plant, as it will still have most of its foliage left.

In most summers, but not this one, the Oriental poppies would have gone dormant and disappeared. Too bad, because if you could find the plants, it’s easy to dig their roots during summer dormancy and simply cut them into 2-inch sections, and each of these 2-inch sections can be replanted to get a new poppy plant. These sections will be about the thickness of a pencil. Replant them at the same depth that you found them, and make sure they are planted vertically and not horizontally. Also, maintain the same orientation with the thicker portion at the top, thinner at the bottom. You’ll only get some foliage next year from these root divisions, but they will flower nicely the following year.

And then there are the peonies. You can pay from $15 to over $100 for peony roots—but if you’ve got a nice plant or some older plants that need rejuvenation, now is the time. Note, though, that I’m speaking of herbaceous peonies and not tree peonies, which are grafted. This work is done very similarly to the way the irises are dug, divided and transplanted.

With irises, our keyword was “fans”—and how many fans you would get with each division. With peonies, we’re not looking for fans but for eyes. Each division that we want to make should have at least three eyes and possibly four. These “eyes” are bud eyes similar to what you find on seed potatoes or potatoes not treated to sprout or develop eyes. The digging steps are similar to those used for the iris, so if you’re successful at one you’ll easily master the other.

Using a tine or pitchfork, slide the tines under the roots, not through them, and gently leverage them up and out of the ground. The fork should be inserted into the ground straight down several inches from the visible crown, then push the handle backward to force the plant out of the ground.

Once the soil is loose and the roots and the plant are free, you can use your hands to remove the plant from the soil. Shake off any remaining soil and start to look for bud eyes. With a sharp knife, cut the crown so you have at least three eyes with each division. You want at least one three-eye division, as this will flower in a year or two, and two-eye divisions will take two to three years.

Now, remove the foliage using a pruner—but don’t cut too close to the crown. You can leave up to a half inch of stem and use that as a marker. Cut off any rot or damaged root, and allow the divisions to air dry for about an hour.

Next comes the planting. Peony roots planted too deep won’t flower, and too shallow may be damaged from winter heaving. Look at the parent plant and the depth it was planted. Planting should be so the bud eyes are clearly visible but just peeking above the soil. No fertilizer is added, and no mulch should be used. Simply plant, water in and let Mother Nature do the rest.

A biostimulant can be used with the first watering, and then, if we don’t get rain, water the new plants weekly through late November. There’s a chance that three- and four-eye transplants will flower next spring, but most likely it will be the following year.

Divide, multiply and keep growing!