The underground portion of the hosta plant is called the crown. It is the point of growth for hostas and all leaves and flower stems originate from buds on the crown. The roots extend out of the bottom of the crown.

Larger hostas have a thickened crown that may become quite large as the plant matures. To obtain a division capable of developing into a new plant, there needs to be enough so that a piece may be removed that contains some of the crown, some roots and either a leaf (during the growing season) or buds (during the dormant part of the year). Many of the larger hostas tend to multiply slowly and may not produce a lot of buds each year.

Smaller hostas may have a thinner, intertwined root system. Often these start with the original division and then grow by  rhizomes out to the sides in all directions. Again, as long as you can separate them so that you end up with a piece of crown, stems or buds and roots, you have a division. Cultivars such as ‘Golden Tiara’ multiply quickly and may be divided almost yearly if you need more plants to spread around your landscape.

Hostas may generally be divided “when the shovel is sharp” but this depends on post-division care. If you keep them adequately watered, they will survive division most any time. However, the cool days of the spring and the fall are the best for assured success.

Be sure to use sharp tool when you make divisions. Ragged cuts tend to stay open longer and may lead to rot problems. Although you will often hear the advice to dip the cut crowns in a fungicide, there are millions of hosta divisions made each year without this step. It would be more important if you have an existing problem with root rot in your garden. Generally, it is not needed.