Jerusalem Artichokes are not artichokes at all they are a big sunflower and have tuberous root like a potato. It is the root that you eat. They are grown as an annual meaning that you replace them each year.
The Jerusalem artichoke, also called sunroot, sunchoke, earth apple or topinambour, is a species of sunflower native to eastern North America, and found from eastern Canada and Maine west to North Dakota, and south to northern Florida and Texas. Wikipedia
There is a great blog post here which deals with the pitfalls of growing these plants and how invasive they can be – after reading this I decided that there is no way I am setting them loose in my garden. I might give them a go but I will plant them in a smart pot which will allow me to grow them without the hassle of them going weedy and invading my yard. You can get smart pots from garden centers and Amazon has them for about $15.00 for a 15 gallon one which should be big enough. You could also use these to grow any other plant once the artichoke season is over.
They can grow up to 10 feet tall and about 18 inches wide. They are happy in most soil types. People usually plant them along a fence so that they won’t put extra shade on your garden. If you are growing them in a smart pot you will need to protect them from the wind and they will dry out quicker so will need more water.
Plant tubers in late winter or early spring. about 8 inches (10-15 cm) deep and 20 inches (50 -60cm) apart. Scatter some fertiliser when you plant.
They get yellow flowers in summer – you should remove these when the buds form.
Harvest them four to six weeks after the flower buds form or when the stems die down which should be in late autumn. While you can leave them in the soil until you want them they can get weedy and invasive if you don’t dig them up every last one each year.
You should get about 12 tubers per plant.