Why stop harvesting rhubarb in midsummer?

Ceasing harvest of rhubarb by midsummer will ensure that the plant survives. By late summer, rhubarb is storing energy in its crown to produce stalks the following year. If rhubarb is overharvested, it has to expend its energy to regrow, using up its reserves, sort of akin to using its battery up for the winter. I had a neighbor in Vermont who lost a 7-year-old plant for this very reason; they were simply taking too much off each year.

After harvesting, rhubarb's foliage continues working double time to recover carbohydrates. A study conducted by a Michigan State University researcher found that plants needed 90 or more frost-free days to replenish their carbohydrate stores. July 1 is the cutoff date for northern gardens to get that 90-day frost-free period, while my Alaska-based clients told me July 15 is sufficient. Growers from the southern US should stop earlier to account for longer growing seasons.

Thin stalks indicate overharvest. At a Minnesota farm, through continuous picking until Labor Day, the stalk diameter decreased over three years, to the point of thirty percent picking. It took mainly two years of no harvest to significantly recover. Patience pays. Allowing plants to go dormant with full foliage provides a winter kill cushion around the crowns.

Care in the fall will be the basis for growth the following year. I top-dress with composted manure in late October and let the earthworms incorporate it by spring. Avoid applying nitrogen fertilizers after mid-July; even spot treatments will spur new tender growth that frost will kill. I recall a Maine gardener who tried to feed in September and suffered complete crown rot on the plants.

Read the full article: How to Grow Rhubarb: Expert Tips for Success