Rhubarb is a perennial vegetable that has a long history of cultivation and use. It is native to the cold climates of the Himalayas and Siberia. It appears in written recipes in England in the late 1700s, and since then has been grown in many countries across the world. Despite being a vegetable, it is commonly mistaken for a fruit, as the majority of recipes that use rhubarb are puddings and desserts. It is also a healthy addition to your diet, being full of fiber, calcium and potassium, as well as lots of vitamins and minerals. With its distinctive thick red stems and large leafy tops – which can grow a meter or more tall – rhubarb also makes an aesthetic addition to the permaculture garden. It favors a cooler climate and does best with a cold temperature while it overwinters in the ground. Areas with high humidity and very high temperatures during the summer months are not as suited to growing rhubarb, but permaculturists in such locations who wish to grow the vegetable can employ a number of planting techniques to moderate the microclimate to ensure a good crop.
Rhubarb plants like to be in full sun, but with cooler air temperatures. If you have high summer temperatures, you could grow the rhubarb in partial shade, but it is likely to form thinner stems than if the temperatures were lower. Consider planting at the leaf line of an apple tree, as the rhubarb’s deep roots are beneficial to the tree, and the flavor of both species is enhanced by their proximity. Other good companion plants for rhubarb are the alliums, such as onions and garlic – and brassicas, like cabbage and cauliflower.
Rhubarb needs a soil that is well drained, and nutrient-rich to a deep level. Prepare the soil before planting by adding lots of organic material. Composted animal manure is particularly beneficial for robust rhubarb growth. This should also help keep the ground draining at an optimum, particularly if you have sandy soil that allows percolation to happen too rapidly. If you have very clay soil, you may want to consider planting your rhubarb in raised beds to improve drainage.
You can plant rhubarb as seeds. However, you will need to cultivate the seedlings in in pots in a greenhouse or indoors during the winter, before planting them out in a suitable location when the weather warms up in the spring. The seeds have a papery casing, so soak in water for a few hours before planting into well-composted potting soil.
The most common method of planting rhubarb, however, is as crowns. These are the divided parts of a mature plant’s roots. Source from an organic supplier or ask neighboring gardeners if they have some to give you – they are likely to be varieties that have done well in climate conditions similar to those on your plot. Plant the crowns just under the surface and allow between 80 and 100 centimeters between individual plants, so they will grow large, leafy stems, and not compete with one another too much for soil nutrients and moisture. Plant in the summer, water well, and mulch with straw or grass clippings.
In the spring, add well-rotted manure or liquid manure to encourage strong stalk growth. Keep well watered, particularly during the hot summer months, as if the plant dries out the stems will not develop their characteristic juiciness. Water thoroughly less frequently rather than lightly and often (although not so thoroughly that the soil becomes waterlogged), and avoid watering overhead onto the leaves to prevent rot.
If you planted seeds, you are likely to have your first crop available after three years. If you planted crowns, you may be able to take a crop in the first year, but more often than not it is better to wait until the second year, when the plants are well established and the crop is likely to be more abundant. A good rule of thumb is only to harvest stems that are at least one inch across. This avoids harvesting immature plants during the first year or two. Harvestable stems will be a deep red colour and should come reasonably easily away from the crown if gently pulled. It is best to twist and snap the stalks rather than cut them to avoid damaging the crown. Do not harvest all the stalks from a single plant, as you need to leave some to set for growth the following year.
Because of its fibrous nature, rhubarb is usually cooked before eating it. It can be eaten raw, but is extremely tart so will need to be used in a dish that adds a sweet component to offset the acidity. Only the stalks are edible; the leaves and roots contain toxins that can cause digestive problems in humans if eaten either raw or cooked, particularly in large quantities. It is for this reason as well that you should avoid feeding the leaves to your livestock, be they pigs, chickens, ducks or rabbits. The leaves can go on the compost pile, as the toxins they contain – oxalic acid and soluble oxalates – are not easily absorbed by plant roots. However, you still should not let your livestock forage on garden beds that contains compost containing rhubarb leaves.
In the kitchen, rhubarb is usually used as you would a fruit, ideal for use in pies and crumbles that have a longer cooking time to allow the stalks to become soft and palatable, or sliced very finely raw into a salad or dessert. In terms of flavor, it combines well with ginger and apple.
Fresh, unwashed raw rhubarb stalks can be kept in the refrigerator in a plastic bag, and avoid cooking them in aluminum, copper or iron pans, as the high levels of acidity reacts with those materials and causes the rhubarb to turn brown. You can freeze rhubarb for later use. Cut into chunks and blanch in boiling water for a minute before plunging into cold water to stop the cooking process. Rain well and freeze in sealable containers.