Gadenin日本語Get the appWhy the first cut matters more than any other
A purple choy sum plant grows a rosette, then one central stem rises out of the middle of it carrying a cluster of buds. Left alone, that stem opens into yellow flowers, sets seed, and the plant is finished. Cut it, and every leaf joint left below the cut is released to push a side shoot of its own. That is the whole trick of the crop, and it means the height at which you make that first cut is the single decision that governs total yield.
Cut high, just below the bud cluster, and you take a long stem now and leave the plant with only two or three joints in play. Cut low, down at the fourth or fifth leaf from the ground, and you take a shorter stem but leave eight or ten joints, every one of which is a future shoot. The low cut is almost always the right call unless you are clearing the bed anyway.
Timing is the other half of it. Make that first cut while the buds are still tightly shut and no yellow shows. Once even one flower opens, the plant has committed hormonally to that stem, side shoots come away slowly and thin, and the flush you were setting up never really arrives.
| Where you cut | First stem you get | Joints left below | What follows |
|---|---|---|---|
| Just below the buds | Long and thick | 2 to 3 | A short second flush, then the plant is done |
| Halfway down the stem | Good length | 5 to 6 | A solid flush over about three weeks |
| At the fourth or fifth leaf | Short but tender | 8 to 12 | The longest run; five to seven weeks of cutting |
| After flowers have opened | Woody at the base | Any | Slow, thin side shoots regardless of height |
How to make the cut
Use a knife or snips rather than snapping by hand. A snapped stem tears a strip of skin down the standing stem, and that tear is an open wound in wet autumn weather. Cut cleanly on a slight angle so water runs off the stub rather than sitting on it, and leave about half an inch (12 mm) of stub above the leaf joint you are keeping. Cutting flush against the joint damages the dormant bud you are trying to release.
Cut in the morning while the stems are full of water. A stem cut at midday in warm autumn sun is limp within the hour and never fully recovers in storage, and the wound on the plant dries into a hard scab rather than sealing.
Leave the leaves below the cut alone. Gardeners used to tidying brassicas strip the lower leaves out of habit, and here that is actively harmful: those leaves are the power supply for the side shoots you just released, and a stripped plant pushes shoots that stall at three inches (8 cm).
- Wait for the buds to show but stay shut The bud cluster should be visible and firm, the size of a thumbnail or a little bigger, with no yellow showing between the sepals. This is the point of maximum tenderness and maximum regrowth potential.
- Count leaves up from the ground Find the fourth or fifth well developed leaf on the main stem and mark the joint just above it. That is your cut line for a long-cropping plant.
- Cut at a slight angle with a clean blade Leave half an inch (12 mm) of stub above the joint. Wipe the blade between plants if any of them show leaf spotting, so you do not carry disease down the row.
- Come back in seven to ten days Side shoots will be showing as small clusters at the joints. Once they reach six to eight inches (15 to 20 cm) with shut buds, cut each one the same way, again leaving a joint or two at its base.
Pinching the side shoots in turn
The same logic repeats one level down, though with diminishing returns. When you cut a side shoot, leaving one or two leaf joints at its base gives you a small third-order shoot from that point. These are thinner than the first-round shoots, but they are tender, they come at a time of year when little else is cutting, and they cost you nothing but the choice of where to put the blade.
By the third round, the plant is producing shoots the thickness of a pencil and eventually the thickness of a straw. There is a point where the crop stops being worth harvesting, and it is usually when shoots are budding at four inches (10 cm) tall rather than eight. At that point stop pinching, let a few shoots flower for the pollinators if you like, and clear the bed for the next crop.
One deliberate exception: if you want an early-season stem length rather than volume, do not cut low at all. Take the main stem high, take the two or three side shoots, and pull the plant. In a small bed where the space is already spoken for, three good stems now can be worth more than fifteen thin ones over the next month.
Record where you cut and what came back
Mark two or three plants and record the height of the first cut on each, then count the side shoots each one gave. One season of that answers the question for your own conditions far better than any general rule, because a plant that went into autumn large behaves differently from one that went in small.
Also record the date of the first cut and the date of the last usable shoot from the same plant. That span is the number that tells you whether one sowing carries you through or whether you need a second sowing three weeks behind the first.
Never leave a stem to open its flowers on a plant you still want to crop from. One plant allowed to flower and set pods will slow every shoot on that plant, because seed production takes priority over everything else the plant might do.