Hostas can be divided either by taking a slice out of the base of the plant or by digging up the entire root clump and slicing it into pieces.
If you only need one little piece of the roots to start a little hosta plant, use a sharp spade to take a triangular “pizza slice” out of the circular base of the hosta. If you’d like to split the whole plant up into divisions, dig the entire clump up. Then slice it in half with a spade or shovel and garden fork. You can keep slicing the halves in half again as long as each piece has a single bud stem.
How to divide hostas
Hostas are one of the easiest perennial plants to divide. These low-maintenance ornamentals are a favorite of most gardeners due to their glorious leaves and minimal care requirements. They are tolerant of being divided up into pieces, and division can be done during most times of the year, provided the soil isn’t frozen.
There are two popular methods of dividing hostas:
- Taking a slice out of an established plant without digging it up
- Digging up a whole plant’s root ball and slicing it into pieces
There are also special methods of dividing hostas, such as the “Ross method,” in which the base of each shoot is sliced down the center while the hosta is still in the ground.
The most common season for dividing hosta plants is in early spring or right after they leaf out in spring, but they are also often divided in midsummer when it is clear how large the foliage is aboveground.
Fall and winter division is possible but can lead to damage to the crown and roots if freezing temperatures affect air pockets in the soil. If dividing plants in autumn, try to do it in early fall, well before freezing temperatures arrive.
How to divide a hosta by taking out one small piece
The easiest way to divide a large established hosta is to leave the plant in the ground and remove a small piece. This piece can then be replanted to form a new hosta plant. The little hosta clump will take several years to reach maturity in normal growing conditions.
This method of division is often called “pizza slicing” because it involves removing a triangular wedge from the base of the plant, similar to how pizza is cut. This is easiest with large plants that would be heavy to extract whole.
To do this, water your hosta the day before you plan on performing the division. This will help to reduce stress on the plant. Next, use a sharp spade to cut into the soil around the base of the plant, angling the blade from the edge of the plant into the center. Make a second cut to complete the “pizza slice” and pry it up out of the rest of the root system.
Replant the piece in its new location or pot it up in a container. Water both the piece and the original plant thoroughly. Then, refill the hole left in the original plant with rich organic soil or compost. Replace the mulch around the original plant and mulch the soil around the new plant.
How to divide a whole hosta up into pieces
Hostas are often divided by digging the entire plant up and slicing the roots into pieces. This can be combined with transplanting your hosta, or you can simply replant one of the pieces in the original location to grow another mother plant (although this will take a few years).
To divide a hosta in this way, first water the plant the day before you plan to dig it up. This will help to reduce stress on the roots. Next, use a sharp spade or shovel to dig around the perimeter of the plant, being careful not to damage the roots. Try to dig at least as wide as the foliage grows, as the roots generally extend past the aboveground leaves.
If you’re dividing in early spring, try to recall how large the leaf spread is and dig wider than that. If dividing in summer, mark the perimeter width of the leaves on the soil and then cut the leaves back to the base before digging up the root ball.
Use the shovel to pry up the soil under the roots of the hosta. Try to include as many roots as possible. Once the entire root clump is freed from the ground, slice the plant into divisions. Mini hostas and small hostas can be divided using a clean, sharp knife, while medium and large hostas generally require a garden fork and/or a shovel (often placed back to back to split apart the central crown).
Start by dividing the clump in half. Then split each half in half so you have quarters. Try to split the pieces so that each piece has part of the center (imagine slicing a pizza into four large quadrants). You can keep slicing up the bits if you need more plants. Smaller pieces take longer to grow to mature size, but they will eventually reach the size of the mother plant. Each division should have at least one growth bud in the center.
Replant the pieces of the split hosta immediately in their new location or pot them up. You can give them away as free plants or donate them to a local plant sale if you like. Water both the pieces and the original plant thoroughly. Mulch around the new plants to help protect their roots.
How to divide hostas using the Ross method
The Ross method is a special method of dividing hostas. This method involves leaving the plant in the ground and slicing through each of the stems to cause the plant to put on many active growth buds belowground. The Ross method is most commonly used by plant nursery staff on hosta varieties that grow quite slowly and by hosta collectors propagating rare cultivars.
Start by pulling back the mulch away from the base of the plant. Then, carefully pull out the soil from around the base of the hosta so that its crown and the top of the roots are visible. Gently wash the base of the plant with water to get a good look at the base of the stems.
Use a clean sharp knife and go stem by stem. Start by carefully poking the knife vertically into the middle of one of the shoots, right above where the shoot meets the roots. Then, slice the knife straight downwards through the crown and into the soil below. Take the knife back up to the base of the same shoot and stick it into the middle of the shoot at a right angle (imagine making an X pattern inside the stem). Then, pull the knife down into the soil again. Repeat this process with each stem.
The plant may have some dead leaves after this method of division as you are slicing into the base of each leaf fan. Try to give the plant more moisture after splitting it, especially if the plant is being grown in a sunny spot, to increase its growth rate.
Hosta care after division
After dividing your hostas, water the plants thoroughly. You can also add a balanced fertilizer to the soil at this time. Be sure to follow the package directions for application rates.
Mulch around the plants to help protect their roots and retain moisture in the soil. Check on your plants regularly and water as needed during the growing season. Once the plants have become established, they will need less water.