How to Force a Wysteria to Bloom

Prune off any crowded branches by slicing through a downward-facing bud with a sharp knife or pruning shears. Leave one or two buds on each branch. Repeat with any branches that are hanging down as well. Do this twice a year, once in mid-summer and again after blooming in mid-September.

Once every three years, trim any side shoots on the main stem back to within 1 foot of the stem or it will bloom less and turn unruly.

Trim back neighboring plants to ensure that your wisteria is still getting more than six hours of sun every day. This is the minimum amount of sun that it needs to bloom.

Stop watering and dry out the roots once the plant is mature, to encourage blooming. Watering is only required on a mature plant in cases of extreme drought.

Cut off the shoots that sprout up around the base of the main vine as soon as they appear, to encourage the plant to put all its energy into blooming instead of foliage.

Fertilize with low-nitrogen high-phosphorous fertilizer only sparingly in the late fall. Water the plant until all the fertilizer has disappeared.

Drive your shovel through the roots in a circle three feet away from the base of the vine if the standard pruning does not produce any blooms. The cuts should be at least 18 inches deep to ensure you have severed all the roots. This is called root pruning and helps control the amount of nitrogen the vine can receive.

Cut a line with your knife through the bark all around the main trunk of your wisteria. Use this only as a method of last resort. Do not remove any bark. Complete this by late May. The cutting of this girdle causes stress, which encourages blooming the following spring.