Gadenin日本語Get the appWhat you are picking and when it is ready
The crop is the young shoot tip: the top four to six inches (10 to 15 cm) of a growing stem, with its four or five thick, heart-shaped leaves. Those leaves should be glossy, deep green and fleshy enough to feel slightly rubbery when you fold one. Older leaves lower down the stem go leathery and dull and are not worth cooking, so leave them on the plant to feed it.
First harvest comes six to eight weeks after planting a tuber into warm conditions, once the plant has climbed a couple of feet (60 cm) and has several side shoots. After that you can cut every one to two weeks all through the warm season. This is precisely when it earns its place: it crops hard in the heat of high summer, when spinach, lettuce and most brassica greens have bolted or given up, and it keeps going until the nights turn cold.
Harvest in the morning while the shoots are turgid. Cut just above a leaf joint with scissors or a sharp knife rather than pulling, because pulling tears the stem and shakes tubers loose. Each cut stem branches into two, so regular harvesting genuinely makes the plant more productive rather than less.
| Stage | What you see | Action |
|---|---|---|
| Too young | Shoot under 4 inches (10 cm), leaves still pale and floppy | Leave it; it has almost no substance yet |
| Ready | Top 4 to 6 inches (10 to 15 cm), thick glossy leaves, stem still snaps | Cut just above a leaf joint |
| Getting old | Stem bends instead of snapping, leaves dull and leathery | Cut lower, back to a young side shoot, and compost nothing |
| Overgrown | Thick woody stem carrying visible warty tubers | Cut over a sheet, bag everything, do not eat the stem |
| Flowering | Long sprays of small cream flowers with a sweet scent | Cut the sprays off and bin them; they take energy from the leaves |
Always cut over a sheet
Harvesting is the moment this plant is most likely to escape. Handling and cutting stems knocks the aerial tubers off the leaf joints, and they scatter. So before you pick anything, spread a tarpaulin or an old sheet under the section you are about to work on, wide enough to catch what bounces. Cut, collect your greens into a basket, then fold the sheet inwards and tip whatever it caught into a sealed bag for the rubbish.
Look over each harvested shoot before it goes in the basket and pick off any tubers riding on it. They come into the kitchen otherwise, and from the kitchen they go into the compost caddy, which is one of the commonest ways this weed leaves a garden. Trimmings, stalks and tough leaves are rubbish, not compost, every single time.
Sweep the paving after you finish, out to at least three feet (1 m) beyond the foliage. It takes two minutes and it is the difference between a contained crop and a slow, invisible spread down the garden.
Never pass shoots, cuttings or tubers on to friends, a plant swap or a community garden. Almost every recorded infestation of Madeira vine started as a shared plant given away in good faith.
Cooking the slippery leaves
The thick leaves are mucilaginous: cooked, they release a clear slipperiness much like okra, jute mallow or Malabar spinach. That is the point of the vegetable rather than a fault, and it is why it works so well in soups and in dishes where you want body. Raw leaves are chewy and are not usually eaten in quantity, so cook them.
The simplest treatment is thirty seconds to a minute in boiling water, drained and dressed with sesame oil, soy and a little vinegar; short cooking keeps the color bright and the texture pleasantly slippery rather than sticky. Stir-frying over high heat with garlic works equally well and gives less slip. Dropped into a clear broth in the last minute, the leaves thicken it slightly, which is how they are most often used where the plant is a traditional vegetable.
If you dislike the mucilage, cook the shoots hot and fast rather than long and wet, and dress them with something acidic. Long simmering pulls more of it out. Do not eat the woody stems, the aerial tubers or the underground tubers; the eating part of this plant is the young shoots and leaves only.
Harvested shoots keep four to five days in a sealed bag or box in the fridge, but they wilt fast in open air because the leaves are all water. If they go limp, stand the cut stems in water for an hour and they usually come back. They do not dry well, though they freeze acceptably after blanching for a minute, which is worth doing at the end of the season when you cut the whole plant down.
Record your cutting cycle
Write down each harvest date and roughly how much you cut. After a season you will see the real rhythm of the plant in your climate, which is usually a slow start, a fortnightly cut through the hottest weeks, and a sharp fall-off once nights drop below about 55F (13C). That tells you when to start the plant next year and when it stops being worth the space.
Note the date you first see flower sprays and the date you first find aerial tubers on the stems, because both mark a change in how the plant has to be handled. From the day tubers appear, every harvest needs the sheet, the sweep and the sealed bag, and that date arrives earlier each year as the plant establishes.