Rhubarb

(Rheum rhaponticum, Rheum officinale, Rheum palmatun)

If you are considering growing rhubarb in your garden you are probably thinking of the lovely desserts that you will have when you bake up the luminous, long, red, snappy stems. This is a perfectly understandable ambition but the added bonus for you is that you will be growing a plant that is part of a family that has been part of the medicinal horde of herbalists for millennia.
Rheum rhaponticurn is the garden rhubarb that you will grow. It is related to R. pomatum and R. officinale which have been Favorites of Chinese herbalists for more than 2000 years but it is the root of the plant that they use. Not the stems. In recent times Western herbalism has also embraced rhubarb root as a powerful medicine. While your garden rhubarb (R. rhaponticuni is not as powerful in its medicinal effects as the other rhubarbs, it does still possess them to a lesser degree.
One thing to be aware of with rhubarb is that you should beware of the leaves. While the roots are medicinal and the stems are a food, the leaves can be poisonous due to high levels of oxalic acid, so don’t get carried away and eat the whole thing.
 

Your healing rhubarb
Rhubarb contains vitamin A, vitamin C. calcium, and potassium. It is other substances though that attract all the attention to rhubarb. notably anthraquinones and anthocyanins. The major healing effect that herbalists use rhubarb for is that it is a laxative. It contains substances called anthraquinones that irritate nerve bundles in the colon and as a consequence get things moving. If you want to use your rhubarb root in this way you can make yourself a decoction by chopping up between 20 and 40 grams of the root and covering it in around 750ml of water. Bring it to the boiI and let it simmer until you have reduced the liquid to about 500ml. Strain it offand you have three to four doses of rhubarb tea.
Of course, when it comes to the stem the rich color tells you that your eating rhubarb is loaded with antioxidants. In Fact, analysis has shown that rhubarb contains more than 40 antioxidants including powerful anthocyanins. The question is of course whether these antioxidants survive the cooking process.
In a study published in the journal Food Chemistry this question of how the various cooking methods affect the antioxidant effect of rhubarb was addressed. They found that fast stewing, slow stewing and baking all increased the total polyphenol content and overall antioxidant capacity of rhubarb compared to raw. uncooked rhubarb. The patterns of anthocyanin content and total polyphenol content between the different cooking methods suggests that there is a balancing act going when you cook rhubarb. On the one hand cooking facilitates the release of polyphenol compounds from the rhubarb but at the same time it initiates the breakdown of those released compounds.
Baking and slow stewing were found to offer the best maintenance of color through preservation of anthocyanin and the highest antioxidant capacity. In feet, baking for 20 minutes provided well-cooked rhubarb with the highest antioxidant capacity and the highest anthocyanin content.
Interestingly, whereas baking caused an increase in antioxidant anthocyanins. There was a greater decrease in anthraquinone content the longer cooking time progressed. For antioxidant bang for your buck though, bring on the rhubarb crumble, because baked rhubarb is the hot item on the menu.

A word of caution
Anthraquinones are very effective laxatives but this strong effect may not suit everyone. Pregnant women, people with gastrointestinal complaints, and people taking other laxatives should not use rhubarb root. Pregnant women in particular should avoid rhubarb because anthraquinones can cause contractions of the uterus. You should also not use rhubarb root for long periods since long-term use of anthraquinones can eventually lead to the bowel becoming non-responsive.

Grow Your Rhubarb

When to plant: Best grown from crowns, usually available in winter. Can be grown from seed, but it takes longer to produce edible stalks.

 

Climate: Adaptable but grows best in cool to warm conditions, quality is said to decrease as the temperature rises above 27°C.

Aspect/placement: Likes an open sunny position, but also tolerates some shade and will withstand some frosts.

Specific needs: Rhubarb is a hardy perennial that grows to about 1m by 1m in well-drained soil. Before planting prepare soil with well-rotted manure, compost and blood and bone. Keep plants watered and mulched. Apply well-rotted manure annually for continued leaf growth.
Remove flower stems as they appear. Grows well in a pot. The leaves are poisonous, containing high levels of oxalic acid. These can be added to the compost heap. Rhubarb is a perennial that happily grows in the same spot for about three to four years. Then divide it and replant the crowns.

Harvesting: To harvest, pull the outermost stalks in a downward motion away from the crown (don’t cut the stems because this may cause rotting). Don’t over- harvest. be sure that more than half the stems remain on the plant.