Jerusalem artichoke: flower, care & harvest time
Jerusalem artichoke was a staple of the 17th century European diet. Now, it is beginning to make a comeback. This easy-to-grow, low-calorie tuber is a delicious addition to any garden!
Jerusalem artichoke is a perennial heritage vegetable that has been experiencing a bit of a resurgence in the last few years. But what actually is a Jerusalem artichoke? And where does it come from? Read on to discover all there is to know about this tuber-forming sunflower, and find our top tips on growing Jerusalem artichoke at home.
Contents
- Origin and properties of the Jerusalem artichoke
- Some plants look like Jerusalem artichokes
- Pruning, fertilising and caring for Jerusalem artichokes
- Common pests and diseases of Jerusalem artichokes
- Overwintering Jerusalem artichokes
- Propagating Jerusalem artichokes
- Harvesting and storing Jerusalem artichokes
- Are Jerusalem artichokes healthy?
- How to cook Jerusalem artichokes
Origin and properties of the Jerusalem artichoke
Jerusalem artichoke (Helianthus tuberosus), also known as topinambur, sun choke, sunroot, wild sunflower and earth apple, came to Europe from North America in around 1600. It quickly became a staple carbohydrate, but by the end of the 18th century, most people had replaced it in their diets with the potato, and cultivated Jerusalem artichoke only for animal fodder.
Until a few years ago, the vegetable was largely forgotten. Fortunately, the resurgence in growing heritage, regional vegetables is bringing the tasty tuber back into our gardens and onto our plates.
But what does Jerusalem artichoke actually look like? Above ground, Jerusalem artichokes form long shoots with many side branches that are covered with rough, sunflowery leaves. The branches are sparse and break off very easily in the wind. The plant usually reaches a height of 2.5 to 3 metres, and, from August, can flower. However, only a few varieties do so.
You need only glance at the flowers of the Jerusalem artichoke, to realise it is closely related to the sunflower (Helianthus annuus). Both plants have sunny yellow, crown shaped flowers that appear once the days begin to shorten. In the UK, this is around August, but in Mediterranean countries, you may need to wait until October.
The most exciting part of the Jerusalem artichoke, however, is not what you can see, but what you cannot. Over the summer, oval to conical rhizome tubers form underground. They are usually brown to deep red and white on the inside. At the tips of these asymmetrical tubers are nodules that sprout next year’s shoots; Jerusalem artichokes propagate via rhizomes.
Jerusalem artichokes taste aromatic, earthy and a little nutty. No surprise then, that the vegetable is sometimes given the nickname: earth artichoke. Their flavour is also similar to the globe artichoke.
Note: There are a wide range of Jerusalem artichoke varieties, which differ in flowering vigour, growth height, stability, yield and tuber colour.
Nowadays, Jerusalem artichokes are used industrially to produce fructose, fodder and biofuel. For instance, in the production of bioethanol, sugar beet is the only other crop that yields more biomass per hectare than Jerusalem artichoke. And as a renewable, raw material, Jerusalem artichoke is processed into wood chips and burnt in biomass boilers. The energy produced from one hectare of Jerusalem artichokes is the same as over 6000 litres of heating oil.
Note: Is Jerusalem artichoke poisonous? In short, no. The leaves are enjoyed by animals like rabbits and the rhizome tubers can be eaten raw.
Some plants look like Jerusalem artichokes
Above ground, it is easy to confuse a Jerusalem artichoke with some of its relatives. It is the delicious tubers hidden under the soil that set this vegetable apart; if you find one, it must be Jerusalem artichoke. The Heliopsis and cup plant (Silphium perfoliatum), both of which are used in biogas production are particularly easy to confuse with Jerusalem artichoke.
Pruning, fertilising and caring for Jerusalem artichokes
Jerusalem artichoke grows in almost all types of soil, but prefers sandy, humus-rich, loamy earth. It needs plenty of water to support its large biomass, so be sure that your soil can store moisture well without waterlogging. Jerusalem artichokes tolerate full sun and hot days well, provided they have enough water.
Plant Jerusalem artichokes between the end of March and mid-May – the first shoots should start to appear quickly. In dry years, to support root growth, you will need to water your tuber regularly. And in poor soils, regular fertilisation helps increase crop yield.
Our Plantura Tomato Food is a great choice for Jerusalem artichoke fertilisation. It balances potassium and other essential nutrients for optimal tuber growth. Too much nitrogen, and energy will be put towards shoot formation, which stunts tuber growth and decreases their shelf life. Fresh manure tends to produce too much nitrogen, and so it is better to apply granulated fertiliser to the surface of the soil around your Jerusalem artichokes, instead. Do this as you plant your tubers, and for two months afterwards.
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If you are growing Jerusalem artichokes for fodder, cut off the plant’s shoots and fertilise it once in summer and once in autumn. To harvest the tubers, simply leave the plant to grow naturally. In windy areas, tie your perennial to a strong stake. Jerusalem artichokes may be tall, but they are not sturdy.
Common pests and diseases of Jerusalem artichokes
Jerusalem artichokes are very hardy and do not need disease or pest control. There are only two things to look out for: cool, damp conditions can elicit a minor infestation of powdery mildew; and voles, the only known pest of Jerusalem artichokes, can devour an entire harvest underground.
If Jerusalem artichokes are grown on the same patch for several years in a row, Sclerotinia can emerge, which causes rotting at the base of the main shoot. As this fungus survives in soil, be sure to discard any infected plants and rotate your crops the following year.
Overwintering Jerusalem artichokes
Jerusalem artichokes can be left in soil overwinter. In fact, they can be left alone for up to 20 years if they are well cared for – they will continue to sprout afresh every spring and form new tubers each year. To be sure your Jerusalem artichoke survives that long, only dig up a few of the rhizomes each year, in autumn, and leave the rest in the ground. These buried tubers will lie dormant, but sprout again next spring.
Propagating Jerusalem artichokes
Like potatoes, the simplest and most economical way to propagate Jerusalem artichokes is to use the tubers. After purchasing a single variety of Jerusalem artichoke, you can use it again and again by storing any tubers you harvest in autumn, and transplanting them to a new location in spring.
If you wish to breed a new variety of Jerusalem artichoke, will you need to sow Jerusalem artichoke seeds. Unfortunately, the UK’s climate is not warm enough for long enough for the seeds to ripen properly, so tuber propagation is the only viable option here.
Jerusalem artichokes have a habit of spreading through a garden and forming strong, new shoots from the tubers still left in the earth after a harvest. To prevent this, it is best to dig deep and remove all the rhizome tubers from the ground as you harvest a crop.
Note: Completely removing Jerusalem artichokes from the garden can take a great deal of effort, and will require that you regularly dig up the tubers.
Harvesting and storing Jerusalem artichokes
Jerusalem artichokes are very large plants, and promise an abundant yield in summer. But when should you harvest Jerusalem artichokes? And how do you store them? Here are a few things to bear in mind.
Harvesting Jerusalem artichokes
As soon as the leaves fall off your Jerusalem artichoke plant, and the stalks dry out, it is time to harvest. This is usually from the end of October to November. As with potatoes, dig the soil around the plant with a spade and lift out the plant together with the tubers in one go.
As well as a spade or garden trowel, so-called “potato shovels” and garden forks are handy for digging up Jerusalem artichokes and removing any soil that clings to them. Once the individual tubers detach from the roots, they are ready for harvest. At this time, the tubers are perfectly ripe and store well. You can harvest Jerusalem artichokes throughout winter until March, before the tubers sprout again.
Storing Jerusalem artichokes
Jerusalem artichoke skins are quite thin, so do not store them in a fridge for longer than one or two weeks. The tubers do keep in a freezer for about a year, but the best way to store (and overwinter!) them is in moist sand in a cool cellar.
Unlike potatoes, Jerusalem artichokes are fine outside in winter, so you need not store them at all, if you don’t want. Instead, you can harvest the tubers throughout winter, until new shoots form in March. If the ground freezes, this can become a little tricky, but otherwise: sit back, and relax!
Are Jerusalem artichokes healthy?
The Jerusalem artichoke is an extremely healthy vegetable. The tubers are about 3% protein and 16% carbohydrate, half of which is inulin. Diabetics, in particular, benefit from inulin, which our stomachs treat like dietary fibre. Inulin improves digestion and does not cause blood sugar levels to rise. With about 30kcal per 100g, Jerusalem artichokes have less than half the calories of a potato, and contain vitamins A, B1 and B2, as well as many essential nutrients, like potassium and iron.
How to cook Jerusalem artichokes
Jerusalem artichoke has a pleasantly nutty flavour that can be enjoyed raw or cooked. They taste delicious in soup or roasted with a little oil, mustard, curry powder, salt and pepper.
Tip: There is no need to peel Jerusalem artichokes. Simply clean off the dirt with a little water and a mushroom brush, if you have one.
You could even try slicing the tubers into wafer-thin slices and drying them to make delicious crisps. You can also find Jerusalem artichoke syrup with a high fructose content in specialised shops and even Jerusalem artichoke schnapps or brandy!
Jerusalem artichokes begin growing in May. Read our helpful tips on planting Jerusalem artichokes in your own garden.
