Hostas have become a popular landscape plant in recent years, favored for the plant's interesting foliage, and its ability to thrive in low light conditions. Hostas will grow for many years, and shouldn't be divided if it isn't necessary, or until the hosta is at least five years old. When the middle of the hosta plant dies down, leaving an unattractive bare area in the center of an otherwise healthy plant, the hosta can be rejuvenated by division.
Choose a spot for the newly-divided hosta ahead of time so that the hosta can be planted quickly. Hosta will do best with a few hours of morning sun, but should be planted where it won't be exposed to hot afternoon sunlight.
Use a tiller or a shovel to cultivate the soil to a depth of at least 15 inches. Mix 5 to 6 inches of organic mulch such as compost, peat moss or well-rotted manure into the soil.
Dig up the hosta plant, using a shovel or a garden fork. Lift the hosta carefully from the soil, and rinse the excess soil from the roots with a garden hose. Rinsing the roots will allow you to see the natural divisions in the clump.
Divide the hosta at the plant's natural divisions. Discard the old, unproductive center of the hosta plant, along with any areas that look weak. Cut the hosta into divisions, using a sharp knife or a shovel blade that has been cleaned with a solution of one part household bleach to 10 parts water. The bleach solution is necessary to prevent bacteria from being transmitted to the newly-divided hostas.
Dig a hole for each newly-divided hosta. The hole should be the depth of the hosta's root system, but three times as wide. Add a handful of time-release granular fertilizer to the bottom of the hole, and scratch the fertilizer into the soil with the tip of your shovel. Read the directions on the fertilizer package for exact specifications.
Plant the hosta in the hole, being careful not to plant the hosta too deeply. Plant it at the same soil depth that it was prior to being divided.
Water the hosta immediately after planting. Continue to keep the soil evenly moist for three to four months. After that time, give the hosta about an inch of water every week. Water deeply so that the plant will develop a healthy root system.