Two of my wisteria plants won't bloom...Help!?

I have four wisteria trees that are over 4 years old and get at least 6 hours of sun a day. Someone told me I need to 'shock' them into blooming. I guess that's how plants defend themselves...has anyone had any experience that they could give me any advice? Thanks in advance!

Two of my wisteria plants won't bloom...Help!?
Wisterias can be slow to flower.





The fastest to flower are normally produced by plants that have been grafted - if you look at the base of yours you may see some obvious 'joins' where part of 1 plant has been added to the base of another that can sustain vigorous growth.





Otherwise, there are a few things that you can do to 'encourage' nature along:





1. Ensure that your plant is getting as much sun as possible.


2. Pruning is a valuable method to help -


whilst 2 prunings a year may be too much effort, the better 1 is done in later summer, around August time. You pinch back the current year's shoots to around 12'' or so.





Pruning like this slows the sap in the plant and this encourages bud formation - it's also aided by the ripening / hardening of the wood that forms more quickly than from lots of long shoots. Successive years shorter 'add-ons' of new growth will mean sap is really slow and this is the sort of thing that helps budding to start - same reason why climbing rose branches (plus some fruits etc) placed sideways become good flower producers.





3. Feed and water appropriately


Sulphate of Potash (Potassium Sulphate) provides plants with the element most needed for flowering: Potassium. This is the K in the N:P:K formulations of plant feeds. (Sorry for the chemistry lesson).





You can get Sulphate of Potash at garden centers and places like Home Depot.





You can add general fertilizer too, but I'd suggest that you up your chances of flowers by making sure that there's plenty of Potassium available in the soil, by adding this from mid summer/after pruning (the period when next year's spring flower buds are formed inside of the Wisteria).





Don't allow the area to dry out too much, and also apply a mulch of some sort, such as garden compost. Additional watering will be helpful when the soil dries up, through lack of rain.





Hope these tips help you. I planted a wisteria with my mum many years ago, and we worked hard at getting it to flower. She's old now, but it's just in bloom and looking great.





Good luck! Rob
Reply:Buy some Bloom Booster at Home Depot
Reply:Wisterias are very hard to get to bloom. It can take up to 10 years before they bloom. You can root prune them to get them to bloom sometimes. Sorry to say...you just have to wait.