Manure or custard?
It depends if you are growing it or eating it!
Rhubarb is a strange crop. Firstly, it is not really a fruit – fruits come from flowers. Rhubarb is a vegetable – but we eat it like a fruit. It is also a perennial and plants live for many years. Its popularity is due to the fact that, before the advent of imported fruits, it was the first ‘sweet’ crop of the year. Winter-stored apples will have run out and it was too early for the first summer fruits, so rhubarb was important. I am sure gardeners and cooks waited eagerly for the first pulled stalks in spring and I associate it with Easter, especially when served with baked egg custard.
If you like rhubarb, why not grow your own. It is easy to grow and you can enjoy picking your own for many years to come with minimum effort.
Rhubarb is a large, greedy plant. Because it is simple to grow it is often planted in some-out-of -the-way spot where it will grow but not really thrive. Rhubarb benefits from being planted carefully.
It prefers a moist, rich soil and a sunny spot. It will tolerate part shade but is better in sun. Clay soils are ideal if you dig in lots of organic matter. Sandy soils that are dry in summer are more of a problem because the plants need summer moisture or they collapse in the heat and die back early.
Rhubarb is one of the few crops I would not recommend for patio pots. The plants are too hungry and need too much watering and feeding. And they will die down in summer if stressed and they look awful.
Stress, caused by drought or lack of feeding also triggers flowering. Most rhubarb will send up flowers stems when mature but stress makes it more serious and these stems must be removed as soon as they are seen or the plants will bloom, set seed and be weakened.
You can grow rhubarb from seed, from potted plants and from prepacked plants. Growing from seed is inexpensive but you will have to wait at least two years before you can harvest a crop and your plants will be more likely to flower so I do not recommend this.
You can buy them in prepacks but any for sale now will be dried out and possibly dead. The scraps of plant in the packs are generally small and will take a long time to establish.
It is far better to buy and plant growing plants in pots. These will be healthy and you may be able to pull a few sticks next spring. You can buy them now and get them planted immediately. This will allow you to buy named varieties too, which are always better than plants labelled just ‘rhubarb’.
Before planting, fork in lots of compost or well-rotted manure. Then keep the plants free from weeds and well watered. After that there is not much to do and you will be able to take a crop every spring. The large, spreading foliage will suppress most weeds.
You can harvest from late spring to mid summer. It is best to stop pulling sticks in late June.
There are two reasons for this. When you pull off the stalks and leaves you weaken the plant. It is necessary to allow the plant to make leaves and gain strength after the harvesting period. In addition, the stalks get tougher and will contain more oxalic acid after midsummer. (more of that below)
From a purely practical and personal point of view, although rhubarb is useful in spring, by July we have other fruits to enjoy from the garden so why eat rhubarb? Rhubarb loses its appeal once strawberries are ripe.
In my opinion, the value of rhubarb is that it is an early ‘fruit’ and the earlier it crops, the better it is. So ‘forced’ rhubarb is the most valuable.
The simplest way to do this is to place a large, upturned pot over the clump in spring, just as growth starts. By preventing light getting to the stems it forces them to grow tall and without the green pigment. It encourages them to be tender and pink. But once you have harvested a few crops remove the upturned pot and allow the plants to grow naturally and do not pick more stalks so the plants can recover. You can do this every year.
You can even surround the pot with fresh manure to create some heat and force a slightly earlier crop – and the manure will do wonders to feed the plant.
For an even earlier crop you can dig up a mature plant (no mean feat, believe me!) and put it in a pot in a dark shed or garage. Keep it watered and you will get an early crop but the plants will need to be replanted afterwards and will need a year to recover from the trauma.
Are rhubarb leaves poisonous?
The poisonous element in rhubarb is oxalic acid. Oxalic acid is also found in spinach and sorrel and oxalis, sometimes used to garnish food. It has a distinctive, mouth-watering, sour taste. It is not harmful in small quantities but ingesting very large amounts over a prolonged period (much more than you could comfortably consume) can affect the absorption of calcium and some other nutrients and can lead to kidney stones.
But, generally, rhubarb is very good for your health. It is rich in Vitamin K which is necessary for healthy bones and heart and the fibre and natural mild laxatives promote a healthy digestive system.
Oxalic acid is present in the leaf stalks but in very low amounts. The leaves contain far more oxalic acid which is why you should never eat them.
If you eat too much oxalic acid it can cause nausea. You would have to eat vast amounts of cooked rhubarb stalks to have any ill-effects from oxalic acid. And the natural laxative effects would kick in long before you could eat enough to harm you! But you should never eat the leaves.
However, unless you have a severe allergy to oxalic acid, handling the leaves will do no harm. You can put the leaves on the compost heap or just cut them off and leave them around the plant to decompose. They will not harm other plants or ‘poison’ the compost or soil.
it is unlikely that cats or dogs would chew on a rhubarb plant and if they did they would soon spit it out so unless you have a very inquisitive puppy you should not need to fence off your plant.
Growing Veg Talk this month
Don’t forget that the last of my spring talks, all about growing veg at home, is taking place at the end of next week. I will show you how to grow a wide variety of vegetables in your garden and the dates and times and booking details are here.