Gadenin日本語Get the appWhere the fruit actually comes from
Almost every gardener who is disappointed by a melon or gourd crop is looking at a plant that put all of its energy into one enormous runner. In most of this family the main stem carries mostly male flowers and very few fruiting females; the productive female flowers appear on the laterals, the side shoots that break from the leaf joints of that main stem. Left alone, the plant will run twenty feet (6 m) before it gets around to branching.
Pinching is simply forcing that branching to happen earlier and closer to the crown. Take out the growing tip of the main stem after a set number of leaves and the plant responds within a week by pushing side shoots from the joints behind the cut. Those laterals are where you will get your fruit, and because they are near the base they are easier to reach, easier to water at the root, and easier to inspect for pests.
The exception is bush-habit summer squash and zucchini. Those grow from a short crown with no runner to pinch, and cutting the tip out of one removes the plant. On bush types you manage leaves and airflow instead, never the growing point.
How far to pinch, by type
The number of leaves you leave before pinching varies across the family, and it is worth following the type rather than applying one rule to everything. Count true leaves only, ignoring the two seed leaves at the base, and use a clean thumbnail or snips on a dry day so the wound seals rather than sits wet.
After the first pinch, choose the strongest two to four laterals and rub out the rest while they are still small. Fewer, better-fed vines beat a tangle every time, especially in a small garden, because each remaining lateral gets more light and more root behind it. A second pinch, taken two or three leaves beyond a set fruit on each lateral, stops that shoot from running on and pushes sugar into the fruit instead.
| Type | Pinch the main stem at | Laterals to keep | Fruit per lateral |
|---|---|---|---|
| Muskmelon | 5 to 6 true leaves | 3 to 4 | 1 to 2 |
| Watermelon | 5 to 7 true leaves | 3 | 1 to 2 |
| Winter squash and pumpkin | 7 to 8 true leaves | 2 to 3 | 2 to 3 |
| Cucumber on a trellis | Do not pinch, train the leader up | Side shoots stopped at 2 leaves | Continuous |
| Luffa | 6 to 8 true leaves | 3 to 4 | 3 to 4 |
| Hard-shell bottle gourd | 8 to 10 true leaves | 3 to 4 | 2 to 3 |
Trellis or ground
Going vertical is the single biggest improvement most gardeners can make with this family. A trellised vine gets light on both sides of every leaf, dries within an hour of rain, keeps its fruit off wet soil, and takes up a quarter of the bed area. Powdery mildew, the defining disease of cucurbits, arrives noticeably later on a trellised plant simply because the leaves are not sitting in still, humid air at ground level.
The limit is fruit weight. Cucumbers, luffa, small melons and slender bottle gourds hang happily unaided. Anything above about four pounds (2 kg) needs a sling, and anything above about ten pounds (4.5 kg) is better on the ground. Build the structure before the vines run: threading a six-foot (1.8 m) runner onto a trellis after the fact snaps stems, and cucurbit stems do not heal well.
- Set the structure at planting time A cattle panel arch, a stout A-frame or hog wire on posts. It must hold a soaked, fruiting vine in a summer gust, which is far heavier than it looks in spring. Sink the posts at least eighteen inches (45 cm).
- Tie loosely, every eighteen inches (45 cm) Soft twine in a figure of eight, snug on the support and loose around the stem. Cucurbit stems swell fast and a tight tie will girdle one within a fortnight.
- Sling the heavy fruit An old T-shirt, a mesh onion bag or a length of stocking tied to the frame under each fruit as soon as it reaches tennis-ball size. Support the fruit itself, never the stem it hangs from.
- Guide the ground-grown vines weekly On the flat, walk the bed once a week and lay each runner in the direction you want it. Ten minutes of steering early beats an hour of untangling in midsummer, and untangling always breaks stems.
Leaf and shoot management through the season
Once fruit is setting, the job shifts from encouraging growth to protecting the leaves that fill it. Remove the lowest leaves as they yellow, cut them at the stem rather than tearing, and take out any leaf lying flat on damp soil. A cucurbit needs roughly six to eight healthy leaves behind each developing fruit, so do not strip so hard that you drop below that.
Keep stopping the tips. Every lateral that reaches the end of its space should be pinched rather than allowed to double back over its neighbors, and any new shoot appearing at the crown late in the season should be rubbed out. Late shoots produce flowers that will never finish a fruit before the cold, and they draw from the ones that will.
Do all the cutting on a dry morning so wounds seal before evening, and clean your snips between plants. Powdery mildew, mosaic viruses and bacterial wilt all move readily on tools and hands from one cucurbit to the next.
Keeping a training record
Training is the part of cucurbit growing that most rewards written notes, because the results arrive two months after the decision. Record the date you pinched each plant, how many leaves you left, how many laterals you kept, and how many fruit each lateral eventually finished. After two seasons you will know whether your ground and your summer support three laterals or four.
Note the failures with equal care. A lateral that set four fruit and ripened one small poor fruit tells you to thin harder next year. A plant that ran fifteen feet (4.5 m) with two fruit tells you the pinch was too late. Keep those observations tied to the plant position and the type, so the lesson is specific rather than a vague sense that last year was better.