This week we are going to stray into Horticultural math, specifically, multiplication by division. (Addition by subtraction we will leave for another time.) By this, we mean making new plants by dividing old ones. Often, plants will benefit from dividing every few years or so. It allows for them to have room to develop, will often bloom more, and you get lots of free plants, so it’s win-win for all. This can be a bit daunting if you haven’t done it before, so we will attempt to de-mystify it a bit!
What is dividing? Dividing a perennial means digging it up and separating it into several parts. Each part must have a bit of both root and shoot to be successful.
What can I divide? You can divide most perennials. Perennials with a taproot, such as Baptisia (False Indigo) and Poppies don’t like it very much, and so they are better left alone. And anything woody (with a solid, barky frame that doesn’t die down in winter) has to be propagated another way. But the majority of plants in your garden can be divided successfully.
When should I divide? Most plants can be divided at any time, but a good rule of thumb is to divide fall blooming plants in the spring, and spring blooming plants in the fall. This gives the plants time to recover from the experience and produce flowers at their normal time. Don’t be discouraged if a newly divided plant wilts and looks sad for a week or so after being divided. They like to pout and make you feel guilty, but they will thank you later, trust us.
How do I divide? This is both an easy and a difficult question to answer. The easy answer is that as long as you have a bit of a root and a shoot in your division, you can divide any way you like. A soil knife is a great tool for this. The complicated answer is that different types of plants will appreciate being divided in different ways. Plants like Coreopsis (Tickseed) and Daylilies will appreciate being gently pulled apart, if possible. Irises rhizomes may or may not need to be cut; gently wiggle them around and see if they break up on their own. If not, feel free to cut, as long as there is both root and shoot on each piece. Hostas may need to be cut with a knife, or pried apart with a shovel. (Or two.) It all depends on the Hosta. Some are very densely packed and will need brute force. Others you can pull apart with your bare hands. The thing to remember is that the gentlest approach possible will give you the best results, but that plants want to survive, and are usually forgiving. Just make sure they get plenty of water after planting the divisions, and don’t fertilize them for a few weeks, until they are established. Before dividing, cut back the foliage to 6 inches or so. You want the plants to be able to use their leaves to get energy from the sun, so don’t cut it all off, but the plant will establish quicker with a little less above the soil level to worry about.
It never hurts to Google the plant that you are wanting to divide before diving in, in case there are any idiosyncrasies, but don’t be afraid to try. There are some good how-to videos out there, too. So go out there and pry, tease, hack, and coax to your heart’s content, and enjoy your free plants! Isn’t math fun??!
For more information,click here for a great article.