As Jerusalem artichokes are relatively expensive to buy in the shops, but very easy to grow, they are a useful and cost-effective crop. They also provide a harvest after many other crops have finished, in late autumn and winter.
Jerusalem artichokes (Helianthus tuberosus) are grown from tubers, in a similar way to potatoes, yet unlike potatoes they are very hardy. They are planted directly outdoors in late winter or spring and harvested from late autumn onwards. Each plant should produce 10 or more tubers. These can be dug up whenever you need them, right through winter. And if you leave a few
Despite their name, Jerusalem artichokes are not from the Middle East, but from North America, and are not related to globe artichokes. Instead, they are a relative of the sunflower (Helianthus) and produce characteristic yellow flowers at the top of their tall stems. Their name Jerusalem is thought to be derived from the Italian for sunflower, girasole. They are often known as sunchokes in the US.
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Jerusalem artichokes are grown from tubers rather than seeds. There are only a few varieties sold commercially, which are available in March and April from garden centres and online suppliers.
You can also plant tubers bought in supermarkets or greengrocers. Look for large, firm tubers, ideally as smooth as possible so the offspring will be easy to clean when harvested. Small, knobbly tubers can be time-consuming to prepare.
It’s worth taking the trouble to buy good-quality tubers to start with if you want to continue growing the crop for years. Then you can simply replant some of your harvested tubers every year, as long as they are firm and healthy, or just leave some in the ground to re-grow.
For more veg-growing inspiration, visit the RHS gardens, which all grow a wide range of vegetables.
For the largest crop, choose a sunny planting site with moderately fertile, moisture-retentive yet free-draining soil. Still, these are vigorous plants and can cope in a wide range of conditions, including dry or heavy soil and partial shade, although they may produce a smaller crop. Avoid planting in waterlogged ground, as the tubers may rot.
These sunflower relatives grow very tall (up to 3m/10ft), so when choosing a planting site, make sure they won’t cause problems overshadowing other crops nearby. They may need support in windy locations, but can also act as a useful windbreak if you plant several rows.
Choose a planting site where it won’t be a problem if the plants reappear the following year. Any tubers left in the ground (by accident or on purpose) are likely to re-grow in spring, so artichokes can be hard to get rid of if you no longer want them in that spot. However, on the positive side, this means you don’t have to keep buying new tubers to plant every year.
Before planting, weed the site and enrich the soil by digging in plenty of home-made garden compost.
Planting in the ground
Plant tubers 15cm (6in) deep and 30cm (1ft) apart, in rows, staggered rows or blocks. Allow 1.5m (5ft) between rows.
To produce more plants, you can cut large tubers into two or three pieces about the size of a hen’s egg – just make sure there is at least one bud on each piece.
Firm the soil after planting and water in well.
Planting in containers
If your soil is too wet for planting in late winter or spring, you can start the tubers off in containers outdoors. Then simply transplant the young plants into the ground once your soil is no longer waterlogged. See our guide to transplanting.
If you can’t plant tubers in the ground, you can try growing them in a large container of multi-purpose compost. This should be at least 45cm (18in) wide and deep, to accommodate one or two tubers, at a depth of 15cm (6in). Place the container in a sheltered spot and cut plants down to 1.5m (5ft) in late summer to help it stay upright through autumn gales. Plants in containers need regular watering, especially in hot weather, and are likely to produce a smaller crop than in the ground.
Jerusalem artichokes are strong, vigorous plants and need little maintenance apart from watering in dry weather and sturdy supports.
Water regularly during dry spells in summer, to ensure the tubers swell. Lack of water may lead to smaller, more knobbly tubers that are fiddly to prepare in the kitchen.
When the stems are 30cm (1ft) tall, draw up a mound of soil around the base, about 15cm (6in) high, to help stabilise the plants as they grow.
In windy sites, insert tall bamboo canes around the outside of plantings, linked together with twine, to provide support. This helps to prevent wind-rock, which can loosen the tubers in the ground, hindering growth or even leading to rotting. Supporting them like this will also help to keep the plants tidy.
Alternatively, you can cut the stems down to 1.5m (5ft) in late summer (although you’ll lose the flowers), so they won’t be buffeted by the wind, which can loosen the roots or topple the stems. Don’t reduce their height any more than that though, as it could lead to a smaller crop of tubers.
These sunflower relatives produce cheery yellow at the tops of their tall stems in autumn, adding welcome colour to the veg plot. But you may prefer to remove the flowers, to ensure plants put all their energy into swelling their tubers.
Tubers are hardy and can be left in the ground all winter, for harvesting whenever needed. In colder regions, consider covering the ground with a thick mulch, or other insulation such as cardboard, to deter freezing, so that you can still dig them up during very cold spells.
Save some of the best, smoothest tubers from your harvest and replant them, for a crop the following year. Alternatively, just leave a few in the ground if you’re happy to let them continue growing in the same spot.
Pruning and Training
Cut back any tall stems that get broken by the wind, just below the point of damaged. On very windy sites, it may be easiest to prune all stems back to 1.5m (5ft) in late summer, to prevent wind damage. This means you won’t get any flowers, however plants will then put all their energy into their tubers, so you may get a larger crop.
When the leaves start to turn yellow in autumn, cut down the stems to stumps about 8cm (3in) tall. Leave these as useful indicators of where the tubers are. Place the prunings over the stumps to keep the soil warm and make it easier to dig up the tubers in frosty weather.
They can be stored in the fridge for a couple of weeks, in a perforated plastic bag.
Jerusalem artichokes are persistent and will re-grow from any tubers left in the soil. So if you don’t want them coming back the following year, make sure you remove every last piece. In light soil, the tubers can go quite deep and spread out wide.
The tubers have a nutty flavour and can be used in a similar way to potatoes. Cooking them is simple – just scrub them clean, then boil or steam until tender. Depending on how smooth they are, you can peel them before or after cooking, or, if thin skinned, not at all. They can also be roasted, fried or baked, and made into soups, gratins or mash, or added to stews.
Jerusalem artichokes contain a carbohydrate that is not broken down during digestion and can cause wind, especially if you eat a lot at one time. Try eating small quantities to start with, to see how you react. Cooking them in lemon juice may prevent this side-effect, as may harvesting late in the season – it’s worth experimenting to see what works best for you.
Jerusalem artichokes are healthy, robust plants that rarely suffer serious problems from pests or diseases.
Slugs and snails may eat new shoots, but don’t cause significant damage to older growth. They may also eat into the tubers, especially over winter.
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