Just about everyone knows not to eat rhubarb leaves. It’s one of those pieces of folklore passed down from generation to generation.
What Is Rhubarb?
It’s the long stalks of these large, luxuriant vegetables that you eat. Simply cut or break oﬀ the leafy tops — this removes a toxin called oxalic acid, which is present in the leaves but not the stalks.
Discarded leaves can be added to the compost but should not be fed to animals such as stock or chickens.
Rhubarb is never sold in the greengrocer or supermarket with its leaves on and this is a good rule to follow if you’re passing on a homegrown bunch of rhubarb to friends: always remove the leaves and just give a bunch of stalks.
The other thing about rhubarb that’s a bit confusing is that it’s classified as a vegetable as we eat the leaf stalk, not the fruit, but it’s used as a dessert.
Indeed, with a few clumps of rhubarb in the garden, there’s always plenty on hand for an easy pudding.
Rhubarb is tart, so the stalks are generally boiled with a little water, sugar and lemon juice, but they can also be baked in the oven and drizzled with honey or topped with sugar.
Rhubarb is delicious by itself but it can also be mixed with apple or other fruits and served as a crumble, pie or pudding, added to biscuits or cakes or used to make chutney or jam. Try a spoonful or two on breakfast cereal or mixed through yoghurt.
Rhubarb stalks are at their best in spring and summer, but in very hot climates may grow better in the cooler, drier months.
Common name: Rhubarb
Botanical name: Rheum x hybridum
Aspect & soil: Sun to afternoon shade; deep, well-drained fertile soil
Best climate: Cool to subtropical
Habit: Perennial vegetable
Propagation: Crowns, potted plants
Everyone wants to grow red-stemmed rhubarb. For a long time, I thought that was due to a belief that red-stemmed rhubarb had a better flavor than its less-regarded, green-stemmed sibling.
However, I now think it’s because of the fear of being poisoned.
Some people mistakenly think that green stalks are also inedible, but this is not the case. There are also red- (usually sold as crimson) and green-stemmed varieties available, along with some varieties that are green but flushed with red.
For those who prefer their rhubarb red, look for named varieties including ‘Red Dragon’, ‘Wandin Red’, ‘Silvan Giant’, ‘Sydney Red’ and ‘Ever Red’.
Avoid seed-grown plants, which may be inferior in color and flavor. It has red-to-green stalks with a strong red base. Some red varieties may be greener in midsummer with better coloration in spring and autumn.
There are two distinct types of rhubarb growing in my cold-climate garden. One has very dark green leaves and stout red stalks that can be harvested from late spring to autumn. It’s herbaceous, which means it dies down over winter but re-sprouts in spring.
The other has light-green leaves, a mix of red and green stalks and grows all year, so is available to make delicious and warming winter desserts.
ORIGINS AND CULTIVATION
The rhubarb we grow is a garden hybrid with an exotic heritage. Its ancestors came from Central Asia where Rheum rhabarbarum is found in the Himalayas and Mongolia.
The yellow roots of rhubarb have been long used as a laxative known in Chinese medicine as da huang (“the great yellow”). Its place in the kitchen came later when rhubarb spread along the Silk Road trade route from China into Western Europe.
Initially valued in the West as a laxative, it appears that rhubarb stalks were being eaten in Europe by the 17th century. They have remained popular, especially for home vegetable gardens, ever since.
In the cold northern hemisphere, where rhubarb is dormant over winter, crops are grown in both hothouses and in the field. Dark-crimson hothouse-grown stalks are available in early spring.
Rhubarb is generally grown from crowns (the dormant root system of the plant).
Existing clumps can also be lifted and divided to provide new plants.
Crowns are sold and planted through the cooler months of the year (generally in winter). Plants are also available in pots and these can be planted at any time.
It takes six to 12 months of growth for a new crown or a division to produce thick leaf stalks, so allow the plant to grow without harvesting any stalks for its first spring and summer (or longer if the stalks are still spindly).
Once rhubarb is growing well, it will keep on growing and producing for many years. Stalks can be 40–50cm in length or even longer depending on the variety and growing conditions, but they may be shorter in hot climates or where plants are water stressed.
To get long, thick stalks, grow rhubarb in full sun (or with afternoon shade in summer and in hot climates) in rich, well-drained soil. Space each plant around 1–1.2m apart. Plants can be grown in large pots or raised vegetable beds but need extra moisture and nourishment to thrive in a container.
Before planting a new crown, remove all weeds and dig aged manure into the soil. Place the crown so the top is on the surface of the soil. Keep plants well watered. Encourage strong growth with regular liquid feeding or by adding a mulch of well-rotted manure and compost.
Rhubarb has few pest or disease problems, especially when grown in ideal conditions. Occasional leaf damage, caused by fungal spotting, can occur but usually doesn’t aﬀect the harvest.
In wet or poorly drained soils, rhubarb may rot so in these conditions or where soils are subject to inundation during heavy rain, grow rhubarb in raised beds.
In poor soils, the leaf stalks may be thin. This plant is highly prone to wilting on hot or windy days, so always water thoroughly, especially if you’re planning to harvest it to eat.
In very cold conditions, rhubarb stalks may contain some of the oxalic acid normally found only in the leaves. Cold-damaged rhubarb stems usually look unappealing and will taste bitter. If in doubt, simply remove the stalks and wait for new growth in spring.
Despite its large, leafy habit, rhubarb is a flowering plant. Clumps eventually send up large thick stalks, which carry heads of
small white flowers. Cut flowering stems oﬀ at their base to encourage a return to leafy growth. Plants that are dry or stressed may bolt to flower at the expense of leaf production.
HARVEST AND STORAGE
Harvest thick, glossy stems by snapping them down at the base of the clump to remove the entire stalk and base. Avoid
tugging up or pulling at the stalks as it’s possible to accidentally pull up the entire clump.
Pick the large outside stalks to encourage new leaves to grow. Excess crops can be preserved by bottling (in sugar syrup or water) or turned into fruit chutney.
As well as being used to make desserts, rhubarb can also be served as an accompaniment to meat, including lamb.