Why Is My Rhubarb Producing a Tall Flower Stalk?

A rhubarb plant sending up a thick central flower stalk — which can grow to 60cm or more very quickly — has bolted. This is the plant's attempt to set seed rather than continue vegetative growth. It happens most commonly in old, crowded plants that have not been divided for several years, or in response to drought, heat stress, or a period of cold followed by warmth in spring. The flower stalk should always be removed promptly — allowing the plant to flower and seed significantly reduces the energy available for producing harvestable stems.

How to remove the flower stalk

Cut or pull out the flower stalk as close to the base as possible — do not leave a stub that could rot. The entire stalk, including any developing flower head, should be removed and disposed of (not composted if it has gone to seed). The remaining plant can continue to be harvested cautiously — stop harvesting if the plant looks stressed and allow it to recover its leaf canopy for the remainder of the season.

Why old plants bolt more

Rhubarb crowns that have not been divided for five or more years become crowded, with many small buds competing for the same root space. This congestion stresses the plant and makes it more prone to bolting. Dividing the crown every four to five years into two or three pieces and replanting the strongest sections resets this clock and produces a vigorous, non-bolting plant.

Does the plant recover?

Yes — removing the flower stalk before it fully develops usually allows the plant to continue producing harvestable stems for the rest of the season. The plant is not ruined by bolting, but a plant that bolts repeatedly every season is likely overgrown and needs dividing.