Winter squashes like butternut and pumpkin are long-season vegetables that can take three months or more to fully ripen. They must be completely mature and cured in order to store them throughout the winter. Most varieties tend to grow long, lush vines before they begin to set flower buds, which become the squash fruits. Whether you're growing them on a trellis or on the ground, the vines can often grow longer than you expected. This can mean over-crowded and heavily weighted trellises or a vegetable garden overrun by squash plants. However, a little judicious pruning at the right time can tame the vines without compromising the fruit.
Benefits of Pruning Squash
Pruning back your squash vines won't hurt the plant or fruits, and it won't diminish their flavor. Pruning signals to the plant that time is almost up for the season and it needs to get a move on toward ripening. Since the plant won't be able to set any more fruits—and, by pruning, you aren't letting it grow any more foliage—it can put all its energy and resources into plumping up and ripening the existing fruits. So even if you aren't short on space, but the growing season is drawing to a close, you can speed things up by pruning the vines.
When to Prune Squash Vines
Winter squash needs a certain amount of vine to support and feed the developing fruits, but you don't have to let the vines grow forever. Most varieties will not set more than four or five fruits per plant. Once your vines have set that amount, you can begin to prune them back and keep them in check. While you are waiting for the fruits to set, it's okay to gently move the vines out of the way to make room for yourself or other plants.
How to Prune Squash Vines
If you start pruning as soon as the four to five fruits are set, the vines should be tender enough to pinch off with your fingers. Don't worry; it won't hurt the plant. As long as the main roots of the vine are not disturbed, the plant will continue growing.
- Simply look for the squash that is farthest out on the vine.
- Using your fingers, pinch off the tip of the vine, leaving just a couple of leaf nodes past the outermost squash.
- For unwieldy vines, pinch off more of the vine to get it back to one or two leaf nodes beyond the outermost fruit.
Potential Pruning Problems
One potential problem you may encounter is vines that have rooted. When squash vines touch the soil, they can send out new roots. If the part of the vine you want to remove is near a newly rooted section, you can still lift and remove that section, roots and all. It may cause the vine near the rooted section to wilt for a day or two, but it should recover quickly. Like most vining plants, squash plants also produce tendrils which can attach to other vines or weeds. It's perfectly fine to disentangle and gently pull the vines apart to avoid breakage where you don't want it.
Another thing to keep in mind is that the vines may grow back. As with many plants, pruning back your squash vines once doesn't mean they won't try to grow new stems and leaves. You may have to do more pruning to keep them confined to limited space.
Mulching With Vines
Some gardeners like to use their squash vines as a living mulch. Vines can do a good job of smothering weeds, but they also smother any plant they grow over, including other vegetables, so use them as mulch with caution. The vines are also scratchy and prickly, which makes them unpleasant to walk on and harvest through. This can work in your favor, deterring pests like squirrels, who don't like to walk on squash plants. It helps to wear gardening gloves when working with squash vines.
How to Prune Summer Squash
Pruning is also acceptable for summer squash plants which respond to pruning the same way as winter squash. Rather than waiting to harvest until fully mature, we harvest summer squash while it is still in its tender, immature stage. Summer squash vines will continue setting more flowers and fruits as long as they are harvested young so pruning them will result in a smaller harvest. Summer squashes tend to produce abundantly so if you've over planted, pruning may be desired.
Eventually, summer squash vines will become exhausted and begin to decline. When this happens, you can pull out the whole vine and begin harvesting from the plant you succession seeded for mid-season.