Growing wisteria

My small back yard gar­den has a def­i­nite Asian fla­vor includ­ing asym­met­ri­cal beds com­plete with water foun­tains and trees, bird­baths, tem­ples, wind­ing gravel walk­ways and plenty of flowers.

I think of it as a roman­tic inter­lude, a quiet place to dream and be grate­ful for nature’s beauty. In my mind, all that was miss­ing from this lovely respite was wis­te­ria. Noth­ing rivals the beauty of a wis­te­ria in full bloom with its large fra­grant flow­ers. So, last fall, I decided to add a wis­te­ria arbor to my landscape.

Accord­ing to the Ohio State Uni­ver­sity Exten­sion Fact Sheet “Grow­ing Wis­te­ria” (ohioline.osu.edu/hyg-fact/1000/1246.html), wis­te­ria are vig­or­ous twin­ing vines with wide land­scape usage where space per­mits and gar­den­ers com­mit to keep­ing them in bounds. Among their attrib­utes are har­di­ness, vigor, longevity and the abil­ity to climb high. Two species of wis­te­ria are typ­i­cally grown in home gar­dens: Chi­nese wis­te­ria and Japan­ese wis­te­ria. Japan­ese wis­te­ria is known for its fra­grant vio­let blos­soms borne in 8– to 20-inch clus­ters while Chi­nese wis­te­ria clus­ters are slightly larger. Chi­nese wis­te­ria is not quite as hardy as the Japan­ese and also not as fragrant.

My first chal­lenge in adding wis­te­ria to my gar­den was locat­ing it in a sunny area where the plant would have room to grow. Wis­te­ria requires six or more hours of direct sun per day and a deep, mod­er­ately fer­tile, moist soil. Although they will adapt to most soils, a slightly acid soil pH of 6.0 to 7.0 yields best results. Because my gar­den is small I had to make a small com­pro­mise (this may later prove to haunt me) by locat­ing the arbor within a foot of a mature Brad­ford pear tree. I added a gravel walk­way under­neath and relo­cated sev­eral day lilies to make room.

I know that good site prepa­ra­tion will help ensure plant estab­lish­ment. I pre­pared the soil in an area two to three feet in diam­e­ter and 18 to 24 inches deep. I mixed peat moss and com­post to improve soil aer­a­tion and drainage. I pur­chased at end of sea­son an inex­pen­sive sturdy metal trel­lis and secured it in the ground, as wis­te­ria climbs best on wires, trel­lises, arbors and per­go­las. I placed the root ball of the plant in the hole at the same depth as it grew in the nurs­ery and filled in the hole with the soil mix tapped firmly around the root ball.

Also impor­tant to suc­cess­fully grow­ing Wis­te­ria is water­ing, feed­ing and prun­ing. It does not like to be dry. It is par­tic­u­larly impor­tant to water when the flower buds for next year’s bloom are being set usu­ally August through Sep­tem­ber. Wis­te­ria does not need much nitro­gen at all since it is a legume and capa­ble of fix­ing its own nitro­gen. How­ever, if a soil test deter­mines inad­e­quate lev­els of potas­sium, apply super­phos­phate (at the rate of two ounces per square yard and potas­sium sul­phate (one ounce per square yard) in the spring. Wis­te­ria should be pruned but sources vary on when. One source said late spring or early sum­mer; another said late August and early spring.

Like most gar­den­ers, I was drawn to wis­te­ria for its blos­soms so you can imag­ine my dis­ap­point­ment this spring when it failed to bloom. I later learned that pro­duc­ing only veg­e­ta­tion is one of the plant’s noto­ri­ous ten­den­cies. I heard of one case where the wis­te­ria plant failed to bloom four years in a row. The owner adopted a puppy who promptly chewed the wis­te­ria to the ground. The fol­low­ing year, the wis­te­ria was wild with blos­soms. I think the les­son to be learned is that wis­te­ria love to be pruned.

Age of the vine is a major fac­tor deter­min­ing whether a Wis­te­ria will flower or not. Vines grown from seed may need 10 to 15 or more years in order to pro­duce flow­ers. Vines grown from cut­tings or grafted plants typ­i­cally flower sooner. Also, in severe win­ters, flower buds may be injured or killed. Suc­cess­ful wis­te­ria gar­den­ers often rec­om­mend root prun­ing, apply­ing super­phos­phate, rig­or­ous prun­ing for the shoots and plant­ing in full sun. As for me, I think I will just get a puppy.

Michele Pear­son is an OSU Exten­sion Mas­ter Gar­dener volunteer.

Posted by Master Gardener on Sep 28 2012. You can follow any responses to this entry through the RSS Feed. Comments can be made below.