Q.Can phosphorus be added in springtime for wisteria vine?
The once-blooming wisteria vine now produces perhaps one or two blooms. The vine gets sun and is pruned in January. Can I add phosphorus now or do I need to wait until the Fall?
Certified GKH Gardening Expert
I would add this about 2 weeks before you expect flowers in your area. Really, though, as long as it isn't dormant you can add it at just about any time.
This article will give you more information: https://www.gardeningknowhow.com/ornamental/vines/wisteria/growing-wisteria-proper-wisteria-vine-care.htm