Rhubarb is another great perennial vegetable to include in your edible garden! Plus once you get a couple plants established, they readily multiply, giving you years of bountiful harvest. Though botanically a vegetable, most often we cook it and eat it like a fruit. In fact, in 1947, the United States gave it the legal designation as a “fruit”, to avoid the high tariffs imposed on imported vegetables–as it was far cheaper to bring fruits into the country at the time.
Rhubarb can be planted in early spring, or even late winter in milder seasons. Dig a hole large enough to accommodate 4” of compost and crown, leaving room for 2” of soil above crown roots. Put about 4” of well-rotted manure or well-aged compost into the bottom of the hole. Nestle rhubarb crown into compost and cover with soil. Gently compress the soil around the root and water well. Plant crowns 24-36” apart.
And keep in mind; your rhubarb bed will be in place for at least 5 years without being tilled or worked, so place it in a practical space and don’t skimp on organic material!
Keep the bed well-watered for the first summer while the roots are developing a strong connection with the soil. After the first year, mulch the bed with compost or well-aged manure once a year, in early spring, to keep it vigorous and productive. Keep it well weeded.
Unfortunately, you cannot harvest any stalks the first year, as the newly established crowns need to build up their strength. In subsequent years, harvest by tearing the stalk off, pulling sideways, away from the center of the plant. If you cut them with a knife, the stubs can get decayed and infected. Rhubarb sprouts in early spring, often earlier in our PNW climate. Begin harvesting as soon as the leaves first appear and continue until the stalks get too tough and stringy. Do not take more than half the stalks that come up or you’ll drain the root’s food reserves too much.
The leaves are not edible because they contain huge amounts of oxalic acid. But laid around the plant, the oxalates in the leaf mulch act as an effective weed-killer. It is wise to cut off the plant’s flower stalks as soon as they appear, allowing the plant to put more energy into storing food in its rootsystem.
MAINTAINING THE BED
The crowns will divide steadily. If you want to harvest large, succulent stalks, this competition must be reduced. So, about every 5 years the roots must be dug, divided, and replanted in another spot. Do this in early spring, while the leaves are small, as soon as they begin to appear. First, deeply cut an 8” circle around the roots with a sharp shovel. This severs the surface feeder roots. Then, cut under the crowns 9-12 inches down. Then, levering up with that same shovel, lift the crown, and by hand, gently separate the crowns-there will be many. Do this without damaging the growing points. If the growing point on top of the crown is broken off, the root will die.