The biggest problem with Wisteria that fail to bloom is usually due to an abundance of nitrogen which produces foliage rather than bloom and a phosphorus deficiency. To remedy the situation amend the soil in the fall with 1/2 lb of colloidal sulphate or the same amount of bone meal per 1" of the main trunk diameter. However, be aware that it may be several years after planting before this vine blooms. Root pruning of established plants may encourage shy bloomers to perform. Prune the Wisteria severely after it blooms to encourage further blooming and to control excessive growth (which can be as much as 10ft a year); prune all new growth back to three buds.