Feeding A Wisteria

[Vimto]

I have a wonderful pergola with a wisteria at each corner which now covers a large area of my garden. It has taken around fifteen years to develop into the glorious flowering spring delight it has become. I never put nitrogen near it as this creates far too much verbiage. Every year in very early spring I give it a liberal dressing of potassium which id certainly not doing it any harm. A friend has suggested I use phosphate or even superphosphate instead but I'm reluctant as I always thought that phosphate was applied to encourage root growth. Have the gardeners out there any comments?

[murraymints]

sulphate of potash early spring to promote flowering