My sister-in-law, Dixie, has a problem. Sadly, she’s not alone. Here’s her tale of woe:
I need help with my wisteria vine on the east side of the house porch. It must be about 40 years old as I planted it after we were married, and it has only bloomed one year. I don’t know what I did to it to make it bloom that one year. Any suggestions?
The Planting Queen says: Good luck. Wisteria seems to be one of those plants that gives gardeners the most plant envy . You’d think it would be easy, since wisteria actually thrives on a certain amount of neglect. But it may take up to 7 years to get blooms from a seed-grown plant.
You probably have one of these: Chinese (Wisteria sinensis) or Japanese (Wisteria floribunda). Chinese wisteria flowers grow in clusters 9 to 12 inches long that appear before the vine leafs out. (Fun fact: The vine winds counterclockwise around supports). Japanese wisteria’s larger blooms on 12- to 18 inch-long clusters show up at the same time as the leaves. (Fun fact: The vine winds clockwise.)
There are other kinds, such as American wisteria (Wisteria frutescens) which doesn’t grow as large.
Wisteria needs at least 6 hours of full sun per day but more is better. The east side of your house is OK as long as that big tree nearby doesn’t shade it too much.
And it may need some tough love, aka pruning. Try whacking it this year in the hope it will produce blooms next year (because wisteria flowers on “old wood.”) But now is the PERFECT TIME to rejuvenate that wisteria.
Here’s how to do it in two stages: Right now (early spring), cut back any new shoots from last year to the second or third bud. These should become flowering spurs for this year or next year. In July, cut any of this year’s new shoots to 6 to 9 inches. Those will be the shoots you’ll cut back next spring to the second or third bud.
The 40-year-old wood may need a bigger shock. Try root pruning right now, early spring. Drive a sharp spade vertically into the soil around the wisteria at a radius of about two feet from the main stem.
Fertilizing: Wisteria will produce leaves but no blooms if it’s anywhere near a lawn fertilizer that’s high in nitrogen, which boosts leaf production. If you’re fertilizing your lawn anywhere near the roots, stop that.
Even a balanced 10-10-10 fertilizer won’t work. Wisteria needs a fertilizer with a high second number (the sequence stands for nitrogen-phosphorus-potassium). The phosphorus helps in developing flowers. Apply right now according to package directions.
Planting Queen tip: Don’t be afraid … prune that puppy! After 39 years of no blooms, what do you have to lose?
Questions? Just ask in the comments section below.