Climbing wisteria vines grow to more than 7.6 metres (25 feet) tall. The white, pink, blue, purple or lilac flowers hang down in clusters that bloom from April until June. The wisteria vine is a vigorous plant that requires a moderately moist and fertile soil with a pH level ranging from 6.0 to 7.0. Proper soil preparation for wisteria ensures the vines overall health and beauty. Healthy wisteria vines are less susceptible to pests and diseases.
Soil requirements are the same for Chinese Wisteria and Japanese Wisteria. The flowering vines require at least six hours of direct sunlight in fertile, well-draining soil that is slightly acidic. Dig a hole that is at least 60 to 90 cm (24 to 36 inches) in diameter and 60 cm (24 inches) deep. Collect a small sample of soil for testing. Place the soil sample in a sterile container. Put the dug out soil to the side or place it in a wheelbarrow. This makes it easier to mix in any soil amendments before planting.
Bring the soil sample to your local garden centre for testing or test it with a kit. Thoroughly mix calcitic limestone, dolomitic limestone or wood ash into the soil to raise a low pH level. To lower a too-high pH level, mix a fertiliser containing ammonium nitrate or ammonium sulphate into the soil. Composted leaves, leaf mould, peat moss, pine needles or sawdust also lower soil pH levels when mixed into soil. Both Chinese Wisteria and Japanese Wisteria vines thrive in acidic soils but tolerate slightly acidic soils.
If you have a rich, loamy soil, mix composted organic matter or well-rotted manure into it. Loamy soils are dark and feel crumbly rather than sandy or solid. For soils heavy in clay compounds, thoroughly mix 900 g (2 lbs) of builder's coarse sand and compost into the soil to improve drainage. Improve moisture retention and the structure of sandy soils with generous amounts of compost. For all soils, mix in a fertiliser that is high in potassium. Potassium assists root development of newly transplanted plants. Add the newly amended soil back into the hole. Save any leftover soil mix to mound around the wisteria vine.