Quite possibly you may never have heard of this grape before. I found out about it a few years back while researching disease resistant early red grape varieties. This one was developed a few decades back in Germany by crossing a vinifera variety Dianna, with a hybrid Chambourcin. The result was a red grape that showed tremendous disease resistance and ripens in about 95 days (bloom to harvest). It has been recommended for those short season vineyards where disease resistance is a priority. I have been in touch with the owner of Hollywood Hills vineyard on the west coast and he has been growing Regent for 10 years. He says he has never had to spray this variety and like other accounts, it ripens in about 95 days. (Link to his blog - it is excellent and worth a look). Given the humidity of the area that seems pretty impressive. The grape trials at Mt. Vernon in Washington have also tested this grape and found it can ripen in about 1700-1800 degree days F and ripens about a 7-10 days after Castel 19637 (another excellent disease resistant, cold hardy, early, hybrid)
I haven't found much details about its cold hardy properties but have read a few notations here and there on the net from people who grow Regent (another good blog) and have said it is hardy to about -13 to -14 F. That is about -25 c. Another document says Regent is hardy to about -5 to -10 F, that is about -20 to -23 C. Peter Salonius who grows this variety in New Brunswick recommends covering this vine if you expect winter cold below - 20 c. (He also lists it as being mid-season for his locatiopn which gets about 900 ddg C or 1650 ddg F on average). So perhaps using this more conservative number -20 C or -5 F could be used as the bench mark. We had about -20 c as the coldest day this past winter at our site so we'll be able to test that on the taller canes that were sticking out above the snow.
What I have also found out is that it apparently makes excellent wine. There are several accounts of this and the fact that the German acreage of this variety has grown from about 400ha in 2000, to just over 2100ha in 2007 is proof that this grape has excellent qualities beyond the disease resistance. It apparently has the ability to reach good sugar accumulations and excellent chemistry for making wine. One German study over a five year found it was superior to Pinot Noir in this respect. Germany's wine authorities have even labeled this grape as being vinifera due to the excellent qualities of the Regent grape and the fact that it has so little non-vinifera genes in its ancestry.
While I have not yet tasted a Regent varietal wine, Hollywood Hills as mentioned above is making it as such. What I have read is that is can make a heavier red wine with complexity and taste similar to a Merlot. I've also heard that is can make an excellent rose as well.
Other sources label it as an excellent wine.
Our Regent is coming into its second year so no crop this year but we will keep a few bunches on the row to give us an idea of ripening times and to see what the juice chemistry is.