Gadenin日本語Get the appThe low cut is what starts the shoots
A kailan plant has dormant buds sitting at every leaf joint down the main stem. While the main stem is growing, the tip suppresses those buds. Cut the tip off and the suppression goes with it, and within four or five days the buds at the joints you left behind start to swell and push. Cut the plant high and you leave only one or two joints to work with; cut it low and you leave three or four, and each one is a future stem.
This is the difference between kailan as a one-shot crop and kailan as a cut-and-come-again crop. Growers who pull the plant after the main stem often conclude it is not worth the space; growers who cut above a low leaf get three or four times the yield from the same bed. The right height is 4 to 6 inches (10 to 15 cm) above soil level, immediately above a healthy leaf. Leave two or three leaves on the stub. Those leaves are the engine for the regrowth and stripping them, which people do out of tidiness, is the commonest cause of a plant that simply sits there after cutting.
- Choose the joint before you cut, not after Look at the plant from the side and pick a leaf joint 4 to 6 inches (10 to 15 cm) up with a leaf that is still green and undamaged. Cut half an inch (1 cm) above it at an angle.
- Leave the leaves alone Do not tidy the stub. Two or three leaves left below the cut feed the new shoots. A bare stub can only draw on the root and regrows slowly if at all.
- Feed and soak within a day A high nitrogen liquid feed and an inch (25 mm) of water tells the plant to spend on regrowth rather than to shut down. Do it the same day you cut, not a week later.
If a stub shows soft brown rot at the cut face in wet weather, slice it back cleanly to firm tissue with a sharp knife rather than leaving it. The rot travels downward and will take the shoots with it.
What the shoots are like and how long they last
Side shoots are not miniature copies of the main stem. They are thinner, typically a quarter to a half of the diameter, they come with more leaf relative to stem, and they are noticeably sweeter and more tender than the stem you cut first. Many growers prefer them, and they cook faster, so treat them as a different vegetable rather than a lesser one.
The first flush arrives 10 to 14 days after the main cut in warm weather and up to three weeks in cool. After that a well fed plant produces a rolling supply for four to six weeks. Each successive flush is thinner than the last, and the point at which the shoots come up pencil thin and flower almost immediately is the point at which the plant has finished.
Expect a plant grown at 6 to 8 inch (15 to 20 cm) spacing to yield three to five usable shoots in the first flush and a similar number over the weeks after, roughly doubling or tripling the total weight taken off the plant.
| Stage after the main cut | What appears | Stem thickness |
|---|---|---|
| Days 4 to 6 | Buds at the leaf joints visibly swelling | Nothing to cut yet |
| Days 10 to 14 in warm weather | First flush, three to five shoots | Half the main stem, very tender |
| Days 14 to 21 in cool weather | First flush, slower but often thicker | Half to two thirds of the main stem |
| Weeks three to five | Second flush from lower joints and the base | A third of the main stem |
| Weeks five to seven | Thin shoots flowering almost at once | Pencil thin, the signal to pull the plant |
Pick constantly, and pick before the buds open
The single rule that keeps shoots coming is that no shoot on the plant is ever allowed to flower. One shoot that opens its flowers and starts setting seed tells the whole plant that its job is done, and shoot production drops away within days. Walking the row every two or three days and cutting everything ready, whether you need it that evening or not, is what sustains a long run.
The shoots move faster than the main stem did, because the plant is older and more inclined to flower. A shoot can go from tight buds to open flowers in three days in warm weather, so cutting only at weekends loses you a proportion of every flush. Cut shoots at their base, right where they emerge from the main stub, and take them with their leaves. Do not snap them off, since a snapped shoot tears a strip of bark down the stub and that strip is a route in for rot.
- Walk the row every two to three days Cut everything with swelling buds regardless of quantity. Shoots left because there were only two of them will be flowering by your next visit.
- Cut at the base of the shoot Take the shoot off flush with the stub using a knife or pruners. Leaving an inch (2.5 cm) of stump behind creates a dead peg that rots rather than regrows.
- Remove any shoot you have missed If one has opened its flowers, cut it off and compost it anyway. Leaving it on the plant suppresses everything else.
Feed the plant back into production
A plant producing side shoots is doing the same work it did to build the main stem, but from a smaller root system and with fewer leaves. It runs out of nitrogen quickly and, unfed, it will give you one modest flush and stop. A liquid feed at half strength every two to three weeks through the shoot period is the difference between a fortnight of picking and six weeks of it.
Water matters just as much. The shoot flush coincides with the warmest part of the season in a spring sown crop, and a stub with a reduced leaf canopy dries out at the root more easily than a full grown plant did. Keep to an inch (25 mm) a week and mulch the stubs if you have not already.
Watch for aphids at this stage. They colonise tight new shoots in preference to mature leaves, and a shoot with gray cabbage aphid packed into the bud cluster is not worth eating.
- Half strength liquid feed every two to three weeks A high nitrogen feed poured around the base, not on the stub. Full strength on a cut plant scorches the new shoots as they emerge.
- Mulch the stubs An inch (2.5 cm) of compost around each stub steadies the moisture at the roots, which is where the shoot flush is actually limited.
- Squash aphids in the bud clusters weekly Check the tips at every picking and rub out any colony while it is a dozen insects. Once the cluster is packed the shoot is unsalvageable.
When to give up on a plant
There is a point where a kailan stub is occupying good ground for very little return, and recognizing it early is worth more than persistence. The signals are consistent: shoots coming up pencil thin, buds opening within two or three days of appearing, and lower leaves yellowing from the base upward despite feeding. That plant is finished and no amount of nitrogen will change it.
Pull it, chop the top for the compost pile, and leave the root in the ground to rot if clubroot is not a concern in your soil. If it is, lift the root and burn or bin it rather than composting. Then sow or plant the space immediately; kailan clears quickly and there is usually enough season left for a fast follow-on crop.
The one reason to keep a spent plant is deliberate flowering. One plant left to bloom at the end of a row supports hoverflies whose larvae eat aphids on the rest of your brassicas, and the flowers themselves are edible and pleasant in salad.
Do not keep a spent plant simply because it is still alive. A stub producing pencil thin flowering shoots yields a few ounces over the fortnight it takes a fresh sowing to reach baby cutting size in the same space.