Nothing signifies a poor winter and a fluctuating spring like rhubarb flowers. These triffid like stalks erupt from the ground in a swelling bud the size of a baby. They quickly send up a thick and fleshy shoot, which when cut is hollow, and teeming with water. Many new to gardening see these glorious flowers arcing up and take it as granted that this is what rhubarb does. All vegetable plants produce flowers, but what happens to those vegetables after they set seed?
They die. Now, if you're in the USA you will be saying that rhubarb is a fruit and certainly in the States since 1947 it has been classed as fruit because of regulations and duties. Yet the simple fact is that rhubarb is one of those odd vegetables that we harvest as a fruit. This wasn't always the case and the first recorded use of this plant was in 2700BC as a purge for people with gut, lung and liver problems. Senna Pods have nothing on rhubarb. If for any reason you come across anyone who has taken a tincture of rhubarb root - and we'd seriously advise against making your own - then it is not simply a case of stand back, it is more a case of run away and take cover. Marco Polo valued it so much that he went searching for it China and it's value was equivalent to Chinese silk in the fifteenth century. Rhubarb is named after the Greek rha and barbarum; rha refers to the plant and to the River Volga where the plant could be found growing for miles along the river course. Barbarum refers to a kind of plaster over raw wounds. For centuries, this plant that we cover in custard was more likely to be used to cover you. Also, Polo didn't value the stalks, it was the roots of the rhubarb plant that were being used to save lives and clean out guts. It wasn't until a happy accident in 1817 at the Chelsea Physic Garden when workmen digging in winter accidentally covered rhubarb crowns with soil. The following spring they removed the soil to find the first forced rhubarb, these stalks had a superior taste and quality, from there on in this vegetable used for it's medicinal qualities became a culinary revolution. However, rhubarb is one of those marmite plants and there are some on our Facebook Page who loathe it's taste but this is a complex plant, and it's uses are many from cordials to chutneys, from crumbles to schnapps, from poultices to herbal medicine. If you don't like the taste of rhubarb then all we ask is that you consider it as a foliage plant for difficult areas in the garden, as it is a difficult plant to kill off.
Yet, rhubarb can have problems but here is some common sense advice to grow your skills further:
- Varieties of rhubarb that have been placed under stress or had an access of nitrogen will flower. The solution to this is to remove the flower as you would a stalk by twisting and pulling at the base of the flower shoot. Leaving a flower on a crown will weaken and inevitably lead to the crown not having enough reserves to get through winter. Your harvests will dwindle and your crown will die.
- You may have crowns with thin weak stems and this means you should divide the crown. This tends to happen every 5-6 years. You divide the crowns in winter by digging them up and using a sharp spade to cut them up leaving a bud on each crown. This bud is what produces the stalks. Discard any rotten parts of the crown.
- When harvesting rhubarb don't take all the stalks because this will weaken the crown. Remember to remove the leaves.
- The leaves of a rhubarb are poisonous, full of oxalic acid. Even though the leaves are poisonous they can be added to the compost heap as the acid will be neutralized by the compost.
- Yes, you can make a spray with the leaves to kill aphids and deter other sucking bugs but under EU law we are not allowed to tell you how to make this but we cannot stop you from Googling it.
- You are advised never to harvest rhubarb after the third week of July. This allow the crown time to build up reserves for winter. When the stalks are hit by the first frost, pull them loose and lay the stalk and leave around the crown to allow it to mulch down.
- Never, never eat rhubarb that has been hit late in the year by frost. Gardeners who pick stalks from crowns in October - and yes sometimes they are still growing - are at risk of oxalic poisoning. When a rhubarb crown is hit by frost, it pulls back the oxalic acid from its leaves into the crown and that means the stalks will be full of the poison.
- Always keep the crown clear of debris, this prevents rot setting in.
- Sometimes stalks split. This is largely down to a fluctuating season that goes between wet and hot. You are advised to mulch well in early spring.
- Some summers can be hot and dry, this leads to an abundance of bitter tasting stalks and in these incidences a mulch would have helped along with a good water. In these seasons you are best harvesting the rhubarb early in the day when it is cool and still moist.
- Rhubarb will actually stop growing above 32c (90F).
Rhubarb is also an easy plant to grow and cultivate for a new gardener, as it promises high yields after the third year of growing. We have looked a dividing but how do you grow it?
- Prepare the site you are going to place the crowns in early-autumn. Make sure this is partially shaded. Rhubarb does extremely well in a forest garden. Add plenty of well rotted manure to the soil 3-4 weeks before planting. This allows you to hoe off any weed seeds that you disturb.
- If you have brought your crowns in pots, water them well 30 minutes before taking them out of their pots. This loosens off the pots and means the root ball has a better chance of staying in one piece. It also prevents the crowns from drying out as many gardeners who plant rhubarb, forget to water before and after planting. One is better than none.
- In late autumn, dig a hole big enough to take the crown. Make sure the buds of the crown are level with your soil height. You can even leave them a little proud if you are going to follow with a mulch.
- Gently firm the soil in around the crown.
- Water well. We reckon one large watering can a crown does the plant good.
If you want to grow from seed, see our video and follow up.
So, what have we learnt about rhubarb? #saveourskills
- It's older than most of our vegetables in our garden.
- That the roots where as valuable as silk.
- That it wasn't until relatively recently that we started to eat the stalks.
- Never harvest rhubarb after the third week of July to allow it to recover
- That the leaves of rhubarb are extremely poisonous but that they can be composted.
- Flowers should never be left on a rhubarb crown.
- How to plant, lift, divide rhubarb in winter.
- How to grow it from seed.