Myths About Growing Rhubarb in Scotland

“Rhubarb stems become dangerously toxic later in the season as oxalic acid builds up”

Oxalic acid build-up through the season happens mostly in the leaves, which aren't eaten, and the amount present in the stems is insufficient to have a toxic effect.

Our read Rhubarb's genuinely poisonous leaves are well known, and it's an easy step from there to assume the same risk creeps into the stems as summer goes on. The answer is that it doesn't, at least not to a level that matters.

What to do: Eat rhubarb stems as normal through the season without special caution about a build-up of oxalic acid, and continue composting the leaves rather than worrying about their oxalic acid content, which breaks down as they decompose.

“You can harvest rhubarb normally in its first year after planting”

Take no stems in the first year, only a few in the second, and wait until the third year to harvest normally, so the plant has time to get properly established.

Our read A new plant that's clearly growing well looks ready to use, especially on a crop that's otherwise easy and forgiving. Rhubarb's patience pays off two years later with a plant that can support a full harvest instead of one weakened before it really got going.

What to do: Leave a newly planted crown alone in its first year, take only a light picking in the second, and treat the third year as when normal harvesting genuinely begins.

“Cutting rhubarb stalks with a knife is the best way to harvest them”

Hold the stalk at the base and twist gently to ease it free, avoiding cutting, since a cut leaves a stump that's prone to rotting.

Our read A knife feels like the tidier, more controlled way to harvest almost anything in the garden, which makes it a reasonable-looking default here too. Rhubarb's stem base is the exception, where the clean cut a knife gives is exactly what invites rot in afterwards.

What to do: Twist and pull each stalk free from the base rather than cutting it, saving a knife only for trimming the inedible leaf off once the stalk is already out.

“A rhubarb crown that's been forced this year can just be forced again next year”

The same plant shouldn't be forced in consecutive years; it needs to recover and grow normally instead. The alternative pot-forcing method goes further: crowns forced that way are significantly weakened and usually discarded after harvest entirely.

Our read Forcing looks like a technique rather than a cost, so it's easy to assume a plant can simply be forced again whenever an early crop is wanted. The tender, forced stems are grown by drawing on reserves the plant needs time to rebuild, not a repeatable trick with no consequence.

What to do: Force a plant one year, then let it grow and recover normally the next, rather than forcing the same crown in consecutive years. If you use the lift-and-pot method specifically, plan to replace that crown afterwards rather than expecting it to recover.

“Rhubarb flowering stems are harmless to leave alone, since they're not stems you eat anyway”

Flowering stems should be removed at the base as soon as they appear, since leaving them weakens the whole plant.

Our read A flowering stem isn't a harvestable stalk, so it's easy to assume it's simply neutral, neither helping nor hurting. It draws on the same energy reserve the plant's productive stems depend on, which makes ignoring it a real cost rather than a harmless one.

What to do: Cut out flowering stems at the base as soon as you spot them, rather than leaving them to run their course.

“Rhubarb leaves are too poisonous to put in the compost bin”

The oxalic acid in rhubarb leaves that makes them unsafe to eat breaks down during composting rather than persisting in the finished compost, so it's safe to add them to a normal garden compost heap.

What to do: Compost rhubarb leaves along with other garden waste as normal. The one exception is a worm bin — oxalic acid can harm composting worms, so keep rhubarb leaves out of vermicompost specifically.