How do I divide rhubarb?
You could split the rhubarb the fall or in the spring as the crowns are coming out. While splitting the plant in the fall may not make for very attractive plants after division, the following year, they will emerge healthy exactly where you want them. The advantage of splitting the plant in the late fall is that the plant and its buds will be unharmed in the spring. Just make sure you plant it immediately at the same depth as the original to protect the root from the effects of freezing and thawing.
On the other hand, many people prefer splitting in the early spring. Mark the largest plants to remember which ones you want to split.
To split perennials (including rhubarb), dig the entire root ball and then make a cut half way with a sharp shovel. Try not to damage the crown. You can further divide the half into quarters (you can also use a bread knife for this). The goal is to have enough storage root per bud (red eye) for next year’s plants. Remember that small buds will create small stems; therefore, some of the plants will still give you small plants next year, but will be more vigorous the year after.