Suffolk Grapes

Hi, we live in Vermont zone 5b and would like to discuss other people’s suffolk grape experiences. I bought these as a rooted cutting at tractor supply 4-5 years ago as an addition to our plant nursery for future propagation and sales.
I had saved the packaging in which they came in and specifically stated this is a seedless table grape variety, we have other grape varieties so I didn’t pay super close attention to these until I dug up and moved to a better location in the fall of 2023.
We took cuttings in the winter of 2024 and they rooted well and we sold a handful and grew vigorously in their new spot last season. As the grapes matured and we started eating them both Suffolk plants had big seeds, grapes matured to a slightly darker red color. I had read that sometimes in colder climates a seedless variety can develop seeds, our big concern is we sold these as Suffolk grapes. I contacted the big grower twice that provided tractor supply with these plants as I was assuming they were mislabeled and asking what other possible varieties they grow to narrow down what they are but got no response.
Anybody have similar experiences with a seedless variety producing seeds?

I can't speak to the grapes of Tractor Supply but I have had a couple of times now where I have purchased rose bushes from them that were mismarked.

I have two grapes that should produce this upcoming season, one of them allegedly being a Niagara seedless.

I'll be curious the opinion of others.

Were the ones you bought grafted?

That could make a difference,  especially if the rootstock overgrew the graft.

I don't know tractor supply, but about 10 to 20% of stuff I get from nurseries are mislabeled.   The rhubarb fiasco caused quite a few stomach aches a couple of years ago as new gardeners didn't know it wasn't supposed to have spines.

These grapes were not grafted, just a small 6-7” rooted cutting when I bought them. I read a cornell university article that said sometimes a stressed seedless variety can produce a seed which is not viable. We are very good at labeling our plants and we are skeptical of propagating this really great growing grape again this year if we are unsure of what it truly is. Honestly the grapes look like a Suffolk variety and I believe I ate a few in the 2023 season that didn’t have seeds but I can’t swear to it. I was wondering if the transplanting of these two plants during the fall of 2023 somehow stressed them, one plant didn’t do much growing but the other one went crazy and grew tremendously albeit the seeded fruit.

My red grape will have about 10% of the clusters with one or two individual berries having seed.  This did not happen on the property where they originated but does happen on This property which also has a seeded variety though not close by.

Very interesting Hans, I wonder if some of the seeded varieties nearby could be cross pollinating these Suffolk grapes perhaps?