Our Cold Spring And Late Frost Could Make Your Rhubarb Poisonous
In the Northland, rhubarb grows like kudzu does down south - just about everywhere. So it's no surprise that we have come to utilize - and love - this vegetable. (Yes, it is a vegetable in the horticulture world). Generally speaking - most years - the rhubarb crop is such that friends, family, and neighbors are literally giving it away to share the wealth. But our weather this spring should make you look-twice before you consume it.
Rhubarb is one of those plants where not all of it is edible; in fact, the leaves are toxic and poisonous in some instances. The leaves of the rhubarb plant contain oxalate - which reacts with the metals in our body to create massive problems. It's that reason that we only consume the stalk - leaving the leaves for the compost bin, the garbage, or as mulch for the garden.
In a normal year, the removal of the leaf portion of the rhubarb plant makes the stalk safe to eat. However - cold temperatures can cause the oxalic acid to migrate from the leaf down to the stalk, making that portion of the plant also poisonous. Usually, this isn't a problem - as the last of our cold weather (or frost) comes well before the rhubarb plant first shows signs of sprouting above the ground.
Spring 2019 however has been an unusual year. We've seen colder than usual temperatures later than usual. That sets the rhubarb plant up for a toxic problem.
Master Gardners and County Extension Agents recommend checking your rhubarb plant right now for signs of frost damage. It would be visible as brown, black, or "mushy"-looking leaves; the stalks would also appear soft and mushy. If your plant exhibits these signs - don't eat the rhubarb stalks; the frost has forced the oxalic acid down into the stalks.
If your plant has been damaged by the cold weather and frost, all is not lost. The experts suggest cutting the stalks off (much like you would do at the end of the season) and allow new stalks to sprout up from the ground. Those new stalks would be safe to consume as usual.