Old Wisteria Dropping Undeveloped Pods – Is It In Trouble?

Question

We have a huge 40 year old wisteria vine providing shade over a 14’ x 28’ patio trellis. This year it is dropping 4’ immature seed pods. Don’t remember this ever happening before. We’ve had a few low rainfall years in Northern California – could that be the problem? We regularly trim the vine so it doesn’t overgrow the trellis. Otherwise it has been maintenance free and we don’t water it.

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Answer 1

Some drop should be considered normal. This is, especially, true as the vine ages.

What I see is a very healthy vine. It may be hungry for potassium and phosphorus, but it does not look unhealthy.
You could test the soil for deficiency, but adding just a little "bloom booster" product from one of the many makers will help. Just cut the what the instructions say in half and feed with that.

Once per year will be plenty.

Otherwise, keep caring for that healthy vine as you normally do. They aren't the most reliably flowering plant, so I would say that you are doing a fantastic job of caring for it.

Here is a collection of articles that will give you more information on these vines:

https://www.gardeningknowhow.com/ornamental/vines/wisteria