Jerusalem Artichokes (Helianthus tuberosus) are possibly the easiest vegetable you can grow. You bung them in the ground in March/April, then dig them up again in October-February.
Now you just leave them be. You might need to pile a bit of earth around the stems when they get to 30cm (12") tall to stabilise them, or stake them if you're on a windy site. If they get a bit too tall for comfort, you can cut any stems over 2 meters tall back by about one-third, but no more than that. When the leaves die back after the first frost, cut the plants down to 15cm (6") above the soil & dig up as & when necessary. the tubers will be perfectly happy in the ground (they can be stored in the fridge for a week or two, but are happier in the ground). The 'chokes I sowed last year were slowly dug up & eaten over 5 cold wintery months (the last ones were made into soup at the end of February, and were just as fresh & crunchy as the ones dug up in October). They will also grow in large pots too (this year I'm growing some in empty casks).
They are no relation to the Globe Artichoke, and they're from North America, so where does the name come from? One theory is that it's a corruption of the word Girasole, the Italian word for Sunflower (Jerusalem artichokes are a member of the sunflower family), or a corruption of Ter Neuzen, the Dutch town that introduced the plant to England way back in 1617. The artichoke part of the name is due to Samuel de Champlain, an explorer who first came across the tuber growing in a Native American vegetable garden in 1605. he thought they tasted like Artichokes, and took some home to France, where they were named topinambours and sold by Parisian street vendors. When the potato gained popularity in Europe, the Jerusalem artichoke fell out of favour (and also got blamed for causing leprosy, as the irregular shape & brown mottling resembled the deformed fingers of sufferers of leprosy). They are also known as Sunchoke or Sunroot.
So why aren't they more popular? Well, they are rich in inulin, a starch which the body can't digest. So they're low in calories, but can cause. Uh. Wind. John Goodyer, a 17th century botanist & herbalist wrote "They stir up and cause a filthie loathesome stinking winde with the bodie, thereby causing the belly to bee much pained and tormented." Aww, poor 'chokes. Don't worry, I still love you.
Still, even with the occasional, um, windypops, they are well worth giving a go. They have a sweet, nutty flavour and can be eaten cooked or raw.
They're also not fussy about where they're grown. Ideally they'd like somewhere sunny with well drained soil, but they will also grow in shady spots & dry places, they even flourish in my damp, cold, clay soil. They'll grow where no other crop will (such as under trees or in hedges), they're excellent on new sites as the roots break up the soil & also make an effective summer windbreak, as they grow from 1.5 to 3 meters tall.
March is the perfect time to get them planted. You can plant tubers bought from the grocers, or named varieties bought from where ever you get your seed potatoes (Organic Gardening Catalogue have a good variety - Fuseau - which produce long, smooth tubers that are easy to peel). Plant each tuber 15cm (6") deep & 60cm (24") apart in rows around 90cm (3ft) apart.
Now you just leave them be. You might need to pile a bit of earth around the stems when they get to 30cm (12") tall to stabilise them, or stake them if you're on a windy site. If they get a bit too tall for comfort, you can cut any stems over 2 meters tall back by about one-third, but no more than that. When the leaves die back after the first frost, cut the plants down to 15cm (6") above the soil & dig up as & when necessary. the tubers will be perfectly happy in the ground (they can be stored in the fridge for a week or two, but are happier in the ground). The 'chokes I sowed last year were slowly dug up & eaten over 5 cold wintery months (the last ones were made into soup at the end of February, and were just as fresh & crunchy as the ones dug up in October). They will also grow in large pots too (this year I'm growing some in empty casks).