Hostas are the backbone of the shade garden and you just can't have too many. There are so many choices. So you say you already have the “green one” and “the variegated one”. You need to look more closely and you will see that there are different colors of green - chartreuse, medium-green, almost black-green, or blue-green. Leaf shape can vary from heart shaped, oval, to lance shaped, the borders can be wavy or smooth, and the surface may be crinkled, shiny, satiny, or a combination. Leaf size ranges from as small as a thumbnail to as large as a turkey platter. Plant height and width ranges from just a few inches to three or four feet tall or wide. And that's just green. Multiply that by as many forms of variegation as you can imagine, and you begin to get the idea. There are so many Hosta varieties - hundreds - from which to choose and more new ones available each year that it's hard to know when to stop. The problem is the price. Purchasing new varieties can put a pinch on your wallet, and even varieties that have been out several years may still be expensive. So, how do you get more Hostas and stay within your budget? Easy answer. Buy them when they go on sale in the fall - when they look ratty and ugly and the uninformed shun them. You know they're only going into dormancy and will be beautiful again come Spring! Another way, and absolutely free, is to divide those you already have.
Hostas that are planted properly in well prepared soil will last for many years and do not require dividing. However, if your Hostas have outgrown their location, if you want to move them somewhere else in your garden, if you want to share with a friend, or if you just want more of a good thing, go ahead and divide them. Many gardeners divide their Hostas in the Spring, and there's nothing wrong with that, but Hostas that are divided then may get off to a slow start if the roots are broken off or damaged. Autumn may actually be a better time to divide them in the MidSouth since the plants will not have to deal with the stresses of our summer heat and the roots will have time to establish before freezing temperatures send the plants into winter dormancy. They will get off to a running start in the spring.
Before digging up established plants or removing new ones from their pots, first prepare their new location. Choose a shady to partially-sunny site for your bed. Morning sun is much better than afternoon sun especially in the South. Hostas grow best in moist, but well-drained soil, so prepare it by working peat moss, well-aged compost, composted manure, leaf mold, or finely-shredded bark soil ammendment, or a combination of these deep into the soil. Dig the holes wide enough for the roots to spread out naturally.
If your Hosta is container-grown, the roots may have encircled the pot, so before planting, shake off the soil and carefully spread out the roots or the roots may continue to grow round and round and not down and out as they should. (Add the planting medium from the container to the new hole.) If you are dividing a plant growing in the garden, dig up a generous sized clump, shake or wash off the soil from the roots, and brush or wash the soil off the crown exposing the growing “eyes”. You should be able to tease apart the plant to make more divisions, but you may have to use clippers or a sharp knife, a shovel, or even two garden forks back-go-back to pry apart the clump. Don't be timid; Hostas are hard to kill - trust me on that. Each division should have at least one “eye”, but if your clump is large, you should have plenty and more than one is better. Discard any roots that have broken off since Hostas will not regenerate from root cuttings, but if you find yourself left with an “eye” or two minus roots, pot them up or plant them and see what happens. If any crown tissue is present, new roots will develop.
Hostas that are planted too deeply are prone to crown rot. The crown of the plant should be located at the soil surface at the same level it was originally growing and the roots should spread out evenly. Build a mound of soil in the center of the hole and place the Hosta on the mound “like a hat” or imagine your Hosta is a Jellyfish with the crown and leaves the body and the roots its tentacles. To insure the plant is at the proper depth, lay your shovel or other straight object across the top of the hole. The crown should not be below the surface. If the plant is too deep, remove it from the hole and add a bit more soil to the mound before covering the roots with soil. Do not let newly-divided Hostas dry out for the first two weeks. If you've planted in the fall, don't worry. Any leaves that suffer will die back to the ground at the first frost anyway.
Mulch or no mulch? No mulch - at least over the winter. Hostas are native to colder regions than ours and need cold winter temperatures to look their best. Mulch also harbors slug and snail eggs, Hosta's worst pest. Even in the summer, mulch also provides cover for Voles - Hosta's other worst pest. Voles burrow under the mulch, and munch on Hosta roots. Slugs will make the Hosta leaves unattractive but won't kill them. Voles will. If you really want to kill a Hosta, providing shelter for Voles is one guaranteed way. If you must mulch, at least don't pile the mulch up around the plant. Leave the Hostas in the center of a “doughnut”.
Now pat yourself on the back and wait for Spring!