Gadenin日本語Get the appWhen they are ready
The signal is the foliage, not the calendar. When the leaves yellow and the stems begin to dry, in mid to late autumn, tuber growth has finished and the crop is ready. Digging before that point gives you small, thin-skinned tubers that neither store nor taste as good, because the sugars are still moving down out of the leaves.
Wait longer still if you can. A couple of frosts genuinely improve the flavor, converting some of the stored carbohydrate and giving the tubers the sweet, nutty quality the crop is grown for. Sunchokes lifted in early autumn taste flat by comparison. There is no rush and no risk in leaving them: the tubers are fully hardy and sit unharmed in frozen ground.
| Stage | What you see | Action |
|---|---|---|
| Flower buds forming | Full green foliage, buds at the tops | Tubers just starting to swell, do not dig |
| Flowering | Small yellow daisy-like flowers | Bulking underway, water in dry spells |
| Leaves yellowing | Lower leaves brown, stems drying | Growth finished, cut tops to 12 in (30 cm) |
| After first frosts | Tops dead, stubs standing | Best flavor, start digging as needed |
| Late winter, buds swelling | New shoots forming on tubers | Quality declining, finish the bed |
The ground is the best store you have
Jerusalem artichokes have thin skins and no protective corky layer, so once lifted they lose water fast and go soft and wrinkled within a week or two in an ordinary shed. Nothing you do in storage matches simply leaving them where they grew. Dig what you want for the next few days, and leave the rest.
So harvest runs from the first frosts right through to late winter, a few plants at a time. In areas where the ground freezes solid for weeks, mulch the row deeply with straw or leaves before the freeze so you can still get a fork in. The mulch is for your benefit, not the tubers'; they do not need protecting.
Stop when the tubers start to sprout in late winter. From that point they soften and the flavor goes, and the crop is better cleared than left.
If you must lift and store, pack them in barely damp sand or leafmould in a box in a cold place, or bag them unwashed in the fridge. Either way expect two to three weeks, not months.
Digging without planting next year's colony by accident
Every fragment left behind regrows. That is not avoidable, but it is manageable, and how you dig makes the difference between a row that stays roughly where you put it and one that spreads several feet a year.
- Start a fork's width outside the row The tubers run further out than the stems suggest, commonly twelve to eighteen inches (30 to 45 cm) from the stem. Starting outside that ring and working inward means you lift the outliers instead of chopping them into pieces.
- Lever, do not chop Push the fork in deep and lever the whole clump up rather than driving down through it. A spade cuts tubers in half and each half regrows. A fork brings them up joined and countable.
- Sift the hole before you fill it Run your hands through the loose soil in the hole and take out the small tubers and broken pieces. This one habit is what keeps the colony contained. Ten minutes here saves an hour of pulling shoots in spring.
- Deal with the strays in spring Whatever you missed comes up as isolated shoots. Pull or hoe them when they are ankle high, before they build a new tuber. Cutting them at that size repeatedly does exhaust them, but only if you keep at it.
Handling the tubers you lift, and a warning worth giving
The tubers are knobbly and hold soil in every crevice. Do not peel them; the skin is thin and edible and peeling a knobbly tuber wastes half of it. Soak them in cold water for ten minutes, scrub with a stiff brush, and cut off any deep folds you cannot clean. Cut surfaces discolor quickly, so drop prepared pieces into acidulated water if you are not cooking them at once.
Say this plainly to anyone you give them to: sunchokes store their carbohydrate as inulin, which humans do not digest in the small intestine, and it ferments in the gut instead. The result, in people not used to them, is serious wind and abdominal discomfort, sometimes several hours after the meal. It is not an allergy and it is not a sign of spoilage, but it is real enough that the crop has a reputation for it.
Two things reduce it. Start with a small portion, a few ounces, and build up over a few weeks, as gut bacteria adapt with regular exposure. And cook them long and slow rather than briefly, because extended cooking, especially with acid, breaks some of the inulin down into fructose. Tubers stored a few weeks after harvest also convert some inulin to sugars on their own. Serving a large plate of them to guests who have never eaten them is a mistake people only make once.
Record the total weight lifted from each plant position and compare it with the weight you planted. A well-grown plant returns many times its seed weight; a poor return usually points to shade, drought during bulking, or too much nitrogen.