Forcing Rhubarb: This Growing Technique Will Give You Sweeter Rhubarb
This technique is well-known across the pond, but may be less familiar to gardeners in the US. Learn what forcing rhubarb means, and how it changes one of our favorite spring crops.
Rhubarb is usually known for its extremely sour flavor that’s best tempered with a generous amount of sugar and other fruits (check out these recipes for some inspo). But there’s actually a way to grow rhubarb that produces stalks so sweet you don’t need any sugar at all! Forcing rhubarb is the growing technique that makes this happen, and it also gives growers an early crop.
What Is Forced Rhubarb?
Have you ever brought a plant bulb from a cold garage to grow it inside, like a daffodil or crocus? That technique is known as forcing. A dormant plant is exposed to cold or even frost, and then brought to an ideal climate to start growing. With rhubarb, forcing goes one step further by also blocking all light from the plant in order to get rapid growth.
Why Should You Grow Rhubarb in the Dark?
Growing rhubarb in the dark, and we mean total darkness, accomplishes two things. First, the rhubarb stalks grow faster than usual as the plant searches for light to make chlorophyll. Second, the sweet glucose produced in the rhubarb that would normally be used to grow the plant’s huge leaves is instead stored in the stalks. This means that the stalks of forced rhubarb are sweeter instead of sour.
During forcing, the rhubarb plants will be on the alert for even the tiniest bit of sunlight so that it can begin its natural growing process. Even the beam from a flashlight would be enough to break the forcing! For this reason, rhubarb farmers have been known to pick forced rhubarb by candlelight so as not to disrupt the plants.
Where Is Forced Rhubarb Grown?
Growing rhubarb this way has a long history in England, where the climate much of the year is ideal for the plant. At one time, England produced enough rhubarb to meet the demand across Europe and abroad. The Yorkshire Rhubarb Triangle is a nine square-mile area that’s famous for its early, forced rhubarb. The plants are grown in long forcing sheds and harvested by hand by candlelight.
This is how to harvest rhubarb from your garden.
How to Grow Forced Rhubarb
Choose young rhubarb plants, about one or two years old. In early spring, when a few leaves have just started to emerge from the ground, cover the plant with a large pot. You can even look for special rhubarb forcers: large, terra cotta, bell-shaped containers specially made for the task. Block any holes or gaps in the pot so that no light can get in, and place a layer of straw around the outside of the pot to insulate it. Allow the plant to grow in darkness for about eight weeks before harvesting. After harvesting, the forced plants should be given a season or two to recover before forcing again.