How to Repair Broken Squash Stems

A broken squash stem or vine doesn't have to spell disaster for your harvest. Although squash (Cucurbita spp.) vines look very thick and sturdy, they are actually hollow and prone to both accidental damage and insect infestations. Get in the habit of thoroughly checking your squash stems every day in order to catch and repair split or broken stems as soon as possible and take a few preventative steps to avoid common causes of broken vines.

Why Repair a Broken Squash Stem?

Plants have a vascular system in which water and nutrients travel along tube-like structures called xylem and phloem. When a vine or stem splits open, only some xylem and phloem are affected. Therefore, the plant may not necessarily die, but it may lose water through evaporation at the split. It also may struggle to grow due to the reduced quantities of water and nutrients reaching cells beyond the broken area.

Of course, when a squash stem is completely severed, it has no chance of surviving – without an intervention, that is. Just as doctors can reattach broken blood vessels during surgery, you can reattach severed xylem and phloem through a plant "surgery" called grafting.

Even if you aren't prepared to graft, you can potentially buy yourself some time by placing the broken stem directly in water or burying it in moist soil. Burying is also the go-to method for fixing split stems.

Burying Broken Squash Vines

Because some xylem and phloem remain intact when a squash stem splits, one of the best things to do at this stage is prevent evaporation and encourage new root growth. Burying the stem or mounding soil on top of it accomplishes both of these goals. It's easier to bury a broken pumpkin vine (Curcubita pepo) versus the more upright summer squashes (Cucurbita pepo var. recticollis), but this simple trick produces results on all squash species.

The key is to bury not just any part of the vine but a root node in particular. Inspect the junction between the main vine and a leaf stem for two white bumps, almost pimple-like in appearance. These are the root nodes, and these are what you should bury along with the broken area to give the squash renewed resources. According to Green Adrenaline, it's wise to avoid burying the small leaf immediately adjacent to the root nodes, as this is a brand-new vine ready to take off.

Grafting and Preventing Broken Vines

Because squash will readily produce new roots when the root nodes are buried in soil, it may not be necessary to graft the broken vine. However, grafting is still pretty easy and simply requires a flexible self-adhesive tape, such as specially made grafting tape or even a product like vet wrap.

Using a clean and sharp knife, make fresh, straight cuts on the two ends you'd like to graft together, touch the two ends together and wrap the area with grafting tape. Gardening Know How recommends that you ensure trellised grafted vines have no tension on them, which you can accomplish by creating a sling. In fact, creating slings for trellised squash is an excellent way to prevent future accidents if your butternut (Curcubita moschata) or pumpkin stem broke off from simply getting too heavy.

The other major cause of damage to squash vines is the squash vine borer. These moth larvae burrow into squash vines anywhere they touch soil and feast on the stems. They (and their golden sawdust-like "frass") are easy to spot, but by the time you cut them out of the stem, they will have already damaged your squash plant. Preventing them is ideal and can be accomplished through insecticidal sprays or physical barriers that wrap around the stems.