While the flower or seed stalks should not be used, the leaf stalks are edible. However, the flower stalks should be promptly pulled and discarded. If allowed to develop, the flower stalks reduce plant vigor and next year's production. Dig and divide large, old rhubarb plants in early spring or late summer.
In respect to this, why do rhubarb go to seed?
For a rhubarb plant, that maturity comes a few years after it is planted. The older a rhubarb plant is, the more the rhubarb goes to seed. Heat – Rhubarb plants grow best in cooler temperatures. If you have an unusually warm spring, this can cause a rhubarb to start flowering.
Rhubarb: Sweet and Savory. Rhubarb, the naturally sour stalky vegetable, has a growing season that coincides fortuitously with that of the California strawberry season. That means that 9 times out of 10, you'll see rhubarb combined with strawberries and a heap of sugar, then made into dessert.
Rhubarb is a perennial plant that has stalks similar to celery. Rhubarb is a vegetable, but it is often prepared or combined with fruit for desserts. Rhubarb can be eaten raw, but because of its tart flavor, it is more often cooked and sweetened with sugar.
The year after planting, it's a good idea to fertilize your rhubarb plants in early spring, before the plant begins to sprout significantly. Use an all purpose fertilizer - a 10-10-10 formula works well. Compost or well rotted manure also works well as a fertilizer.
Allow rhubarb to establish for one year before taking your first harvest. Select three of the largest stalks, waiting for the leaves to fully open before pulling from May to August. Stalks are harvested by gently twisting the stems and pulling from the base of the plant.
Rhubarb tolerates very cold (-20 F) very well. Collect the last few stalks after the first hard frost and throw them on the compost pile. Then spread a layer (2-3") or compost (or leaves or hay) to prevent winter winds from drying out your roots. You don't need to do much.
To be honest, rhubarb is “ripe” all spring and summer. But for the health of the plant, there are certain times that you should make your rhubarb harvest. The best time when to harvest rhubarb is when the stalks of the leaves reach at least 10 inches long.
The part that we consume is the petiole or the leaf stalk. Rhubarb leaves should never be eaten since they contain a toxic substance called oxalic acid. All rhubarb leaf stalks/petioles that have been exposed to freezing temperatures should be removed and discarded. The re-growth is safe to eat.
Green rhubarb will always be green. The only sure way to get red stems on your rhubarb is by purchasing dormant crowns of a good quality, properly named, red stemmed variety. It's not that green stems aren't edible. Because crowns are produced by dividing rhubarb plants, they can be a bit hard to come by.
- Wash the stalks and cut off the ends at the base and near the leaves.
- Cut rhubarb stalks into small pieces.
- Place the rhubarb pieces and sugar into a heavy-based saucepan.
- Cover the saucepan.
- Remove from the heat and allow to cool.
- Strain off excess liquid if using in a recipe.
Rhubarb can also be planted in the fall after dormancy has set in. Dig large bushel basket-size holes. Space rhubarb plants about 4 feet apart and plant the roots 1 to 2 inches below the surface of the soil. Be sure to mix compost, rotted manure, or anything high in organic matter in the soil.
So yes, green rhubarb is safe to eat, with the same caveats as apply to any rhubarb. Especially, don't eat the leaves. In On Food and Cooking (2004 edition), Harold McGee indicates that rhubarb tends to be about 1.5-2.0% acid by weight (mostly oxalic acid), which makes it quite tart.
Rhubarb leaves contain poisonous substances, including oxalic acid, which is a nephrotoxic and corrosive acid that is present in many plants. Humans have been poisoned after ingesting the leaves, a particular problem during World War I when the leaves were mistakenly recommended as a food source in Britain.
Since rhubarb is grown for the stems, most gardeners choose to remove the flowers as soon as they appear so the plant can focus its energy on leaf growth. Rhubarb flowers can simply be cut from the plant as soon as you see it appear. If your rhubarb produces a flower, this does not affect the stems and leaves.
The easiest way to store rhubarb so you can enjoy it when it's out of season is to freeze it: cut stalks into 1-inch pieces; lay them flat on a parchment-lined baking pan. Freeze until firm, a few hours. Use frozen rhubarb the same way as fresh—in sauces, pies, and crumbles.
Yes, composting rhubarb leaves is perfectly safe. Although the leaves contain significant oxalic acid, the acid is broken down and diluted fairly quickly during the decomposition process. So go ahead and add rhubarb leaves to the compost pile, just as you would any other yard debris.
Rhubarb prefers to grow in full sun but it will tolerate light shade. A growing rhubarb plant is fairly tolerant of acidic soil and it will grow in soils with a pH as low as 5.0, but it is happiest in soils with a pH between 6.0 and 6.8.