Why Doesn’t My Wisteria Bloom?
The wisteria in Maymont’s Italian Garden has bloomed profusely each spring since 1979, however, the wisteria standard I personally received as a gift 15 years ago has never bloomed. The plant never even set bud to bloom! At first I thought the plant was not receiving enough sunshine. Well over the years, the various hurricanes eliminated that thought as my partial shade to shade home garden became a full sun to partial shade garden.
Then I thought I was fertilizing it too much, so I ceased fertilizing it along with the plants nearby thinking there were wisteria roots lurking beneath. Still the wisteria grew and I spent time pruning and shaping it into various forms to please the kids. I always left the final cuts for mid-winter to reduce each shoot down to 3-5 buds with the anticipation that this was going to be the year it would bloom profusely. Alas, the wisteria in Maymont’s Italian Garden was thriving with this proper pruning technique but mine at home stood there and leafed out, almost in defiance of my efforts.
With the kids grown and on their own I actually had the time to research why my wisteria never bloomed while Maymont’s always did. The answer was very simple and as a horticulturist it was obvious as well. Some nurseries grow their wisteria from seed and like all seed grown plants the off spring have genetic variations. A common trait in seed grown Wisteria it that it does not set flower buds. The plant grows beautifully but never flowers. Gardeners need to purchase plants that are grafted and not grown from seed to insure they will bloom. When purchasing wisteria look for the swollen section of the trunk, be it low to the ground or higher up the trunk for a standard, where the plant was grafted.
Now, after 28 years of caring for a 200' long wisteria arbor I encourage you to ask yourself if you really want to plant this very aggressive plant in your garden. Then ask if you have a very strong support system for this large heavy vine. Remember wisteria requires no less than 6 hours of sunshine, and to hold back on the fertilizer each spring. Every winter prune the significant shoots down to 3-5 buds for a glorious display of cascading blossoms come springtime.
Consider extending your bloom season of wisteria by planting both Wisteria sinensis, Chinese wisteria, which blooms before the plant leafs out and Wisteria floribunda, Japanese wisteria, which blooms after the plant leafs out.
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Peggy Singlemann is a regular guest on Virginia Home Grown, and shares expert gardening tips and information either from the beautiful grounds of Maymont or by answering your questions in our studio.
Peggy, what is your experience with Wisteria frutescens? It's said not to go grow as aggressively so would it need as much support? Would it also have to be grafted to ensure bloom? Also, now that you know it won't bloom, I'm interested to know what you'll do with that massive vine! Thanks. Cindi
The wisteria growing on Maymont's pergola in the Italian Garden bloomed profusely for many decades, it was planted in 1975. We recently removed the plants from the pergola because the vines were compromising the integrity of the historic structure. We then undertook the monumental task of digging the soil from each bed in the garden to remove wisteria roots. This was intense gardening at its best, we not only fully aerated the soil to a depth of 18" but we also reduced the root sprouting wisteria is known for. The final step to the process is grinding away the remaining stumps of the now extant vines.
In my home garden the wisteria that would never bloom is gone thanks to the force of a pick up truck and a strong chain. I then dug out the roots from the garden bed to eliminate any root sprouting in my border. Yes, this took some effort but one that will pay off tenfold come spring when I do not have to battle wisteria vines randomly growing throughout my plantings.
I personally do not have any experience with Wisteria frutescens, American Wisteria. From my experience with a non-blooming seedling at home I would lean toward suggesting you purchased a grafted plant such as the popular cultivar 'Amethyst Falls'. Understand Wisteria frutescens still grows to a 30 foot vine, albeit slower, so be prepared with a support strong enough for that weight or learn quickly how to prune the plant into a unique focal point for your garden.
Richard Nunnally told me do not fertilize anything near the wisteria. They must feel they must bloom to continue to survive. Mine is about your age and it blooms beautifully.
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