Dividing Hostas

First of all, you probably do not need to divide your hostas.  Unlike many perennials that benefit from regular division, hostas can go many years without it and, in most cases, the older they get the better they look.  If your plant is 10-20 years old and the center of the crown does not produce new shoots, then it may be time to divide.  Other than that, the only reason I can think of for regular division is to make more plants, and there is a price to pay for that.

Hostas go through a juvenile period which, from the seedling stage, can last four to five years and even longer.  As they mature, there is a fairly dramatic change in appearance - leaves get bigger, variegated margins get wider, puckering and other leaf textures get more pronounced - just about everything we like about hostas gets better with age.  Unfortunately, when you divide the plants, they revert to the juvenile stage and the process starts over.  That's the price you are going to pay for dividing your plants.  You may not have to wait four or five years, especially if you do not divide too severely, but if you were to divide your plants every two or three years, you would probably never see the fully mature character of the plant.   

So, let's say that you have this gorgeous hosta in your yard and your neighbor/friend/mother-in-law, after gushing about how beautiful it is, says, "Can I have a piece of it?"  Obviously the best answer is "Not on your life!  Go buy your own." (You might even provide them with our web address.)  But if you are too nice to say what you really think, or if this weasel is not going to take "No" for an answer, and if you've never divided a hosta before and you're scared to death you're going to kill your plant, here's how you do it.

There is some question as to the best time to divide.  Traditionally, I think most people considered spring the best time, but lately Bob Solberg, one of our better known hosta gurus has been advocating dividing in the summer.  Bob knows a lot about hostas, so he is probably right, but I've always preferred the spring and I'm kind of set in my ways.  Actually, because of the number of plants we grow here, we divide from March through August and the plants always seem to do just fine, but my preference is to divide as soon as the spears are visible.  

Unlike most perennials, hostas do not grow roots throughout the season.  There is a cycle of growth that starts with a flush of leaves in the early spring, followed by root growth, followed by flowering and seed production.  Some types go through this cycle twice a year, maybe even three times in the South, others only once.  I prefer to divide early in the spring because the plants will put on a spurt of root growth shortly after I cut them.  My guess is, that if you do not divide down to small pieces, it probably doesn't matter.  Who knows.

If you just want to take a small piece from a large plant, or cut it into large chunks, you can take a sharp spade and just push it straight down through the plant.  Just try to aim so that you are sure to get some roots along with the foliage.

This plant does not need to be divided, but we're going to do it anyway.   If you start with a bigger plant, you can either cut pieces off the edge of the clump or slice right down the middle, depending on your objective.  If you just want to take a few small divisions and leave the main plant mostly intact, take a piece off the edge and work with that.  If you are going to divide the whole clump all the way down to small divisions, I would cut it like a pie until I get manageable pieces.
The eyes, or shoots, and the roots grow from the rhizome.  Occasionally the rhizome will be soft and you can just pull the eyes apart.  More often, you will have to cut it apart. Make your cut through the rhizome between the eyes, dividing it and the root mass as evenly as possible.  This plant has four eyes, so we want to cut it half through the connecting tissue, leaving two eyes on each half.
Once you've made your first cut and exposed the connecting tissue, it's pretty easy to see where you should cut again to insure that each piece has a share of the rhizome and the roots.
Nothing to it. Both of these pieces have plenty of roots to survive. You should probably dust the cut surfaces with a fungicide. Even if you get pieces with little or no root, as long as it has some of the rhizome attached, you can treat it like a cutting and it will probably produce roots and survive.    Easy as pie.