My wisteria plant was doing just fine then got spider-mite, I sprayed it with a mixture of dish soap and water, and now two weeks later it seems not to be growing and the leaves are turning blotchy yellow. I re-potted it today as it is in a large container. I have it in a potting mixture from our Home Hardware Store called Marks Best.
Thank you for contacting Toronto Master Gardeners about your irksome spider mite infestation.
Your damaged leaves image shows well the damage caused by the spider mite. The first line of defence we recommend is to spray your plant with a strong blast of water from your hose nozzle, ensuring that you reach all the undersurface of the leaves, and the nooks and crannies where the leaf petiole attaches to the stem. Since our Toronto weather has warmed sufficiently, you could do this outside at present.
This site provides clear and appropriate solutions: https://www.salisburygreenhouse.com/controlling-spider-mites-in-the-home/ as well as the description of the spidermite life cycle.
The mites breed relentlessly, so it will be necessary to spray thoroughly every few days, repeating this for several weeks to ensure that the hatching eggs are knocked off with the blast of water.
If the ‘death by water’ isn’t working, you may need to resort to insecticidal soap, again spraying conscientiously the underside of leaves and the tiny areas where leaf and branch meet and as with the water treatment, repeat every 3-5 days, and keep up this routine for several weeks as each generation of eggs hatches.
Still no progress? Then resort to neem oil or a pyrethrum based spray according to the package directions, and following the previous procedure.
Repotting your plant into the new potting soil should give the plant a boost.
We wish you all the best in saving your potted Wisteria.