Why Does My Homegrown Rhubarb Taste Very Bitter or Sharp?

Rhubarb is naturally tart — that sharpness is part of its character and what makes it so good in crumbles, jams and pies with added sugar. But rhubarb that is unpleasantly bitter or astringent, beyond simply being tart, has usually been harvested at the wrong time of year or is coming from a plant under stress. The flavour profile of rhubarb changes significantly across the season and in response to growing conditions.

Late-season harvesting

Rhubarb stalks harvested in July and August are noticeably more bitter and stringy than stalks pulled in April, May or early June. The oxalic acid content of the stalks increases as the season progresses. The standard rule — stop harvesting by the end of June — exists precisely because late-season stalks are significantly less pleasant to eat. If your rhubarb tastes unacceptably bitter, check when in the season you are harvesting and restrict harvesting to the spring window.

Stressed plants produce sharper stalks

Rhubarb under drought stress, or in poor, depleted soil, tends to produce stalks with a higher relative acid content and less pleasant flavour. A well-fed, generously-mulched plant that is watered during dry spells typically produces noticeably sweeter, more balanced stalks than the same variety struggling in dry or infertile conditions.

Forcing for sweeter flavour

Forced rhubarb — produced under a large pot or forcing jar in late winter, before the plant naturally emerges — is reliably the sweetest and most tender rhubarb of the year. Excluding light causes the stalks to produce less chlorophyll and fewer bitter compounds, and the forced growth is earlier and more delicate. Many growers who find open-grown rhubarb too sharp find forced stems much more enjoyable.