By Vivvyv
United Kingdom 
I have a wisteria growing up a trellis approx 9x9 feet and onto a pergola. Apart from some strong branches the trellis is bare and I want to plant something fragrant to cover it. My preference would be a philadelphus. Bearing in mind the soil here is fairly poor and the ground is covered with paving I would need to dig a few up to access the soil, it would need to compete with the mature wisteria. Would philadelphus thrive here? What else could I plant?
31 Mar, 2012
Answers
Thank you for your advice.. This is the first time I have used this site and I really wasn't expecting any response! So, thank you...today I shall be uplifting a few slabs to determine what is going on beneath the surface.
1 Apr, 2012
The difficulty here is not knowing what the wisteria roots have done - they may have spread fairly close to the surface beneath the paving slabs rather than going deep down into the soil, so you run the the risk of lifting slabs only to find the area is full of roots. If the slabs are simply loose laid, you can just put them back, but more usually, they'll be on a base.
Certainly if you want to risk lifting slabs, you can dig the area, incorporating composted material, and then plant a philadelphus, provided it is placed at least 3 feet away from the base of the wisteria.
31 Mar, 2012