Q. We love rhubarb, but many years ago our huge patch died and we were told there was a disease in the soil. Since then I have tried many times to start new crowns in other spots. The roots go in a deep rich hole and the shoots come up beautiful, but the leaves start to go brown and brittle when they are about 5 inches in size. Soon the plant withers and dies—but amazingly, comes back the next spring. Can you help? I'm dreaming of rhubarb pie and jam!
- ---Bob in Springfield, Ohio
Rhubarb can be planted Spring or Fall. Unless you're sharing someone else's root divisions, the plant will arrive in the form of a crown with eye-like shoots on top. Dig a deep hole—about the size of a bushel basket—and then mostly fill it back up with rich organic matter—compost, well-aged manure—and some sand or soil-free mix if your soil is heavy. Place the crown in the center of this richness, so that the buds are a few inches below the soil line, cover with more manure and compost and then mulch overtop with compost, manure, shredded leaves or straw.
Rhubarb grows best in climates with lots of rain, and has what's known as a 'chilling requirement'; it needs a certain number of nights in the 40's and below to produce well. In naturally cold climates, plant rhubarb in full sun. If you're trying to get it to do well in the South or Hot West, make sure it gets afternoon shade and lots of water.
Although good drainage is essential, rhubarb requires a lot of water. New plantings must be kept moist if rain is scarce; and even established plants need to be watered at least an inch a week anytime it doesn't rain during the growing season.
Most sources say not to harvest any stalks the first year and to only harvest lightly the second year—otherwise the crown will peter out prematurely. When harvesting, try and twist the stalks away from the plant rather than cut them. And, of course, remove and discard every tiny bit of the poisonous leaves.
To produce their best, the plants will need to be dug up and divided every five years or so—ideally in very early Spring, before the new growth begins.
Most sources also agree that rhubarb suffers few to no pest or disease problems. So my diagnostic guesses for the failure in Ohio are: poorly draining soil, lack of watering attention during dry times, lack of sun and/or not enough food. Rhubarb is a HEAVY feeder that wants to be top dressed with lots of compost and aged manure every season.
And it's no surprise that 'dead plants' came back in Ohio. Although you can stress it, rhubarb is hard to kill in cool climes. In fact, it likes to grow so much that real enthusiasts can sometimes harvest a patch all summer long (not just in Spring) by providing shade in hot times, lots of food and water, and harvesting the stalks promptly.
Q. Do you think I'm too far south for rhubarb to do well? My "USDA Zone" is supposed to be 7, but sometimes I see it listed as 8. (I must be just on the line.)
- ---Delma in Coastal NC
- ---The Rev. Tom; St. Paul Lutheran Church; Crawford, TX
Q. My Rhubarb, two years old and growing beautifully, has just developed what look like flowers forming on the top. Should I cut them off to let all the energy go into the fruit stalks (of which I have about 7)?
- ---Tony, just outside Philadelphia on the Main Line.
Q. Hi Mike! Love your show and thought you might like this short video on growing rhubarb indoors here in the UK. Enjoy!
- ---Marc in London