How to Transplant Herbaceous Perennial Plants - Part 2

In my last article, I provided an overview of transplanting herbaceous and woody perennials, along with suggestions for the best season and weather in which to move plants. In a nutshell: transplant early in the spring, after thaw and once the plant is showing very small emerging leaves. If possible, wait until after rain, and work on a windless, cloudy day just before another rainstorm.

As I noted, waiting for that perfect transplanting day can prove remarkably fruitless, as most of us garden when we can fit it into our schedules, so don’t be deterred from transplanting at all by the quest for perfection. As is always the case when dealing with living things, however, understand the risks of moving plants in inauspicious conditions and be pragmatic about the expected result.

One thing we haven’t discussed yet is why you want to transplant. For the most part, you will want to move plants because they have either outgrown their present position in your garden, or you have decided they would be better off elsewhere because they are too tall, too short, too bushy, too scraggly, too similar to nearby plants, too dissimilar to nearby plants or in some other way “too” something. This happens. In the case I’m going to go through, step by step, the clump of false sunflower (Heliopsis helianthoides) I moved fell into several of the above categories: it turned out to be a taller plant than I’d anticipated, and the flowers were so much like those of another tall plant in the same garden patch (Helenium autumnale) that I felt it would be better located elsewhere. All of this happened because — as so often happens among gardeners — I received the plant from a friend who mistakenly thought she was giving me a pot of another plant because she dug up the gift so early in spring it wasn’t clear which plant was which.

If you are fortunate enough to have friends who garden, the same thing may well happen to you, or you may become the bestower of mislabeled plants. One way or another, I had the crazy thing in my garden, it did incredibly well, but it had to be moved.

Step one in the process is deciding where the plant will be moved. Clear that area of leaves, mulch and other debris and dig a hole of the size you think you will need for the transplant, putting the soil in a wheelbarrow.

Now go back to the plant, clean away everything on top of it, as well, and dig all the way around the clump a few inches past its edge, levering upward with the blade of the shovel along the sides of the clump as you go. The goal here is to prune the plant’s horizontal roots slightly, removing only the small ones from the edges of the clump. Should you at this point encounter thick, tough roots, you need to pause and figure out if they belong to the plant you wish to move, or to one of its neighbors. Should they belong to the soon-to-be-moved clump, you will need to extend the diameter of your root pruning or consider a partial bare-root transplant, which is more typical of the way woody perennials need to be treated. Their heavier root mass almost always requires that the roots be pruned more than with herbaceous plants, and often cutting out a root ball large enough to accommodate even well-pruned roots is impractical due to it’s size.

At this point you also need to decide if you will be transplanting the entire plant, or dividing it into two or more clumps. We’ll go into detail on this choose in the next article.

Copyright © Roberta Lee 2012. All rights reserved.

(I am an artist and the author of the Suburban Sprawl series of novels as well as two nonfiction books. Find out more about my work at RobertaLeeArt.com.)