To divide a Hosta, start with a clump that is at least three years old, which
is the perfect size for division. As a rule, the larger and more dense the clump, the less divisions that are possible. On fast growing Hosta, three or four year old plants produce the largest and best
divisions, while slower growing plants or old mature clumps that are eight or more years old, produce the most dense clumps
and are the hardest to divide. These large clumps require a spade and consequently
more destruction of crowns and roots of individual plants as well as a longer period to recover from transplant shock.
The best tools to remove the clumps from the ground are spading forks that have
flat blades or spades. Dig around the clump, starting six inches from the edge
of the crown. Once you have cut a circle around the clump, pry it lose and pop
it out of the ground. On very large clumps in heavy, rocky, or clay soils,
it can be a chore.
Begin dividing the clumps by washing the roots in a bucket of water or with
a hose end sprayer. You will be able to clean the dirt off the crown and the
roots. Do not worry about damaging the roots with the jet of water - they are
tough and can take the abuse. Then turn the clump onto its side and clean again. Do this a number of times. It also helps
to pull the roots up and off to the sides as if to loosen the entire clump as you wash the soil away. Pull each cluster of roots apart. The more dirt you get off
the clump, the easier it is to pull the divisions apart to see where to make the cuts.
Try to keep as many leaves and as many roots as possible on your new divisions so that the plant will grow fast and
become strong for next year.
The next step, after cleaning the dirt off of the roots, is to pull any easily
removable stems or "eyes" from the crown. After you have removed the easy
divisions, wash the clump again repeat the process. Then try to pull the clump
in half. To separate a single plant from the crown, use a back and forth pulling
motion, working the stem back and forth until it comes loose or breaks from the crown.
Keep pulling the different sections in half until you get to the number of stems you want. Sometimes it is easier to work on the plant in the bucket because the water keeps washing the soil away
and provides a lubricant to allow the roots to be pulled out of the clump. If
you separate the clump into nice well rooted single stem divisions, each one will produce a nice plant with one to four stems
next year, all with very large leaves.
If you cannot break the clump apart, a sharp knife will have to be used. Remember, since you want to keep as many roots and leaves as possible, make your cuts
through the crown, but not into the roots. Spread the roots out so that you can
locate a place to make your cut. Start cutting the crown in half by placing the
knife in the center of the crown. Make the cut about half way through the crown
and then see if you can pull it apart by hand using the same back and forth pulling motion.
If you can't pull it apart then make the cut deeper. Once you start making
your divisions you may need to wash more soil off the roots. In most cases, the
reason you divide your Hosta is to increase the number of plants. This process
allows you to divide down to single stems.
Once you have your divisions, the next step is planting them. Do not let the roots dry out at all. If you cannot plant them right away, place some moist soil or peat
moss on the roots and put them in dense shade. If your roots dry a little bit
before you get a chance to replant – soak them in a bucket of water for a while.
Do not leave the plants in water for more than a day because the roots will begin to rot.
For divisions that you have produced by pulling them apart and which have a
nice balanced root distribution – plant your divisions about ½ inch deep. Spread
the roots out and cover the stems until you cannot see any of the white stems or crowns at the base of the stems. Water them
in well so that there are no large air pockets in the soil. If you had to use
a knife and cut up the crown – plant the divisions around 1 – 1½ inches deep and water well. Do not step on the soil around the plants – this will compact the soil.
Hostas can be divided any time of the year, but August is best, because at this
time of the year plants are actively growing new roots. If you divide in the
spring before the eyes have completely expanded, expect to have smaller plants and shorter leaves. The same results will occur if you have to use a knife and cut the crowns. Hostas that
had been divided early and put into pots will be somewhat poorly rooted by fall, but ones that had been put into the ground
will be very well rooted. Those that are potted from August on will be just the
opposite. Hostas in pots will be very well rooted and the ones planted
in the ground will be comparatively poorly rooted.
Next you must add water, water, and more water.
It is the water that minimizes transplant shock and encourages new root development.
If you can keep from severely cutting of the crowns, you can expect good results with a nicely balanced clump. If you divide in late spring after the leaves are out most of the way, many times
you will end up with clumps that look floppy for the rest of the season or until new leaves grow if you choose to cut off
the old leaves.
After some practice and using the advice offered above, you can produce nice
plants that do not even look like they have been divided.