I have a large passion flower plant that I have successfully overwintered in my home for three winters…put it out in the summer and it seems quite happy – lots of amazing flowers!! It has a lot of dead stems under the vigorous live stems and I’d like to get rid of them but I can’t get them out without doing a lot of damage. Is it safe to cut the entire plant back to start over, and if so, when is the best time to do it?
Lucky you to have a Passiflora (passion flower) vine! Pruning can be done regularly, and you can trim the vines throughout the growing season to keep their growth under control, train the plant to keep its shape, and/or to get rid of dead material. A good trim also helps make sure that the plant gets adequate air circulation. As well, pruning results in new growth and more flowering along the vines!
It is generally recommended to prune the plant back by no more than 1/3 of its size. If you prune more heavily, you may not see many flowers the following year. The best time to prune is after the vine has flowered, in the fall (prior to frost) before you bring it indoors for the winter. Remove any dead or diseased plant material — cut this back to where it originates on the main stem, or to the nearest stem that is healthy. To preserve as much of the desirable outer green growth as possible, “go at” the plant from the sides, cutting and pulling out all the dead bits. You should aim to have just one strong, main vines with shoots coming off it. Flowers will bloom on new growth that starts to emerge in the Spring.
Another posting at Ask a Master Gardener may be of interest – Passion Flower Overwintering – although this does not discuss pruning, it provides lots of information on bringing your vine indoors.
All the best with the pruning!