Exploding Wisteria Pods

Wisteria can be seen in several places at Longwood Gardens, and visitors often comment on these growing along the outside conservatory balcony of the Peirce–du Pont House. (Wisteria was once very popular. Other places at Longwood Gardens where they can be seen are the Outdoor Theater and the Wisteria Garden where the plants are trained as trees.) The blooms are spectacular, but they appear early in spring and only last for a short time—about two weeks in early May, and some years it rains for those two weeks. I took this photo a few years ago on a visit for just that purpose. It was a sunny day, and I knew the wisteria was in full bloom. If I waited, they could all be gone.

Wisteria pods

After the blooms are over, the vines are covered with dangling seed pods that resemble melting Lima bean pods. These pods provide interest over most of the winter, and then one day they are gone. I thought that was all there was to it.

Recently, just a few weeks ago, a Longwood gardener was on a cherry-picker at the House trimming back the vines. He said we could hear the pods bursting open. Sure enough, once he mentioned it, I became aware of the constant snapping. He said they were popping early this year, probably because of the dry weather.

As the pods dry on the vine, they twist (here, clockwise, indicating they are a Japanese variety, elsewhere counter-clockwise, indicating a Chinese variety), and this increasing strain eventually causes them to suddenly burst open, flinging the seeds outward. I then noticed the black seeds, also about the size of Lima beans, and the dried, twisted pod remains scattered over the paved areas. They were still raining down as I looked.

All of the wisteria plant is poisonous, especially the seeds and pods.  As few as two seeds can kill a child.  The Longwood staff quickly sweeps them up.  The seeds are very bitter, and household pets, like the late Belin the Cat at Longwood, avoid them.  Children usually quickly spit them out and are unlikely to swallow one, let alone another.

The gardener I was talking with thought of the seeds as a nuisance because they fell into the pachysandra, and he would eventually have to pull up the sprouts. Homeowners are often overwhelmed by the plant’s aggressive growth that grabs onto anything it can wrap its tendrils around, and the beautiful but poisonous vine becomes seen as a voracious evil weed with murder in its heart.  Better you should plant poison ivy.  Or bamboo.  Or forget the hassle of growing them altogether and just visit Longwood Gardens to see them in bloom.  The new season of blooms will soon start, especially with this mild weather.  But hesitate and you will miss them.

Note 4/2017:  I had picked up a few of the seeds at Longwood and poked them into the soil in a window flowerpot, thinking the plants would make a nice souvenir.  They quickly sprouted, and within a few weeks I had sturdy young plants, each now in its own pot.  Thus encouraged, I looked up their care on Google.  I quickly learned that wisteria grown from seed takes about 15 years to bloom, and that ended that project.  I can’t bare to throw them out, so I will probably plant them along a back fence as a gift to a future owner.  I will never live long enough to see the results.

Note 7/2019: I did plant them along a back fence, but between the fence and a drainage ditch. This spring, the county replaced the ditch with a buried pipe. To install the pipe, they had to bulldoze the area, including my wisteria plants which were too small to notice. So, now they are gone, but the future owners will appreciate the pipe more, and I was resigned to go to Longwood Gardens to see wisteria in bloom, anyway.

RWalck@Verizon.net