While it may seem that ungrafted vines are rare creatures, when I started making wine in Oregon about 40% of vineyards were own rooted.
Over the years I’ve worked with quite a bit of ungrafted vines, mostly Pinot Noir, and, while un-romantic, my opinion is that with a good rootstock choice there’s little qualitative difference.
Tasting bottles it’s easy to see things that we would like to see in them. But in tasting over quite a few years from fermenter, barrel, and bottle. This was my personal opinion:
Durant Blocks, Dundee Hills volcanic soils:
Bishop-old vine own rooted Pommard was consistently second fiddle to the grafted block of 114 we also get from directly below it. As the grafted block has aged (from 12 year old vines my first year to 25 years old now) it is showing even greater depth and layers of nuance.
Caveat-row orientation of the Bishop block was not ideal.
Fir Crest-both Block 11 and Block 8 are grafted. In 2019 we took the oldest block of PN as well that are ungrafted. The quality difference was definitely weighted to the grafted vines.
Caveat-this was a one year experiment so hardly a fair study. Though the difference in quality was big enough that I opted not to continue.
In my opinion, there are a lot of micro-climat variations at Fir Crest and Block 11 and Block 8 are well situated to gain the most from some of those variables. That’s not really a graft issue, but I would absolutely say that I don’t think ungrafted vines in a middling terroir will equal or surpass grafted vines in a better micro-climat.
Bishop Creek-old vine ungrafted Yamhill-Carlton fruit. The grafted vines were young vines. The wines from the old vines were more sophisticated and layered. The younger more fruit forward and straightforward as well. Graft or vine age, who knows?
Whistling Ridge-the original blocks were own rooted. Over time there has been replanting with grafted vines on a plant by plant basis. But at no point have I ever felt the best quality wines were coming from the original blocks. I like the original Wadensville block quite a lot, but the best wines always come from the multi-clonal, and multi-rootstock block called Beloved. It’s the material for 90% of the Heritage wines produced from the vineyard over the years.
I’d love to say it was all about ungrafted vines but it’s just not my experience. Though all of the Riesling I have worked with is from grafted plants, so maybe Riesling is different.
But I would guess that site and vine age are still the most important factors.