Uvaggi, assemblage, blend, tagli and cuvée are the terms used when referring to a wine made from grapes of more than one variety, often confusing the correct meaning of these definitions. Let's look in detail at what they are.
In english we just use the term blends- lets see in details what we mean in the details about all the different procedures
Literally, we speak of uvaggio when grapes to produce a particular wine are harvested and vinified together. This used to be the case when there were rows of vines with different types of grapes in random order, so it was not possible to differentiate between them. Everything was harvested together and pressed together, and the resulting must went on to winemaking. The true blend, which is nothing more than a combination of grapes from different grape varieties. From the historical presence in vineyards of different grapes with certain proportions also derive types of wine present today in the specifications of famous appellations of origin such as Chianti, Valpolicella, Rosso Conero and many others.
Actually nowadays it never happens that rooted cuttings of different grape varieties are planted in scattered order in the rows, so the grapes of the different varieties, harvested separately, will go together to create wine at different stages of winemaking (crushing, fermentation, etc.). Numerous variables come into play here, starting with the time of ripening (which can be identical or even very different), the type of wine and the vinification required by the appellation's regulations or chosen independently by the producer depending on the wine to be made.
Tagli and cuvées
In contrast to blending, tagliare il vino (to cut the wine) is a procedure generally used for lesser wines in order to improve them through the addition of other wines with complementary characteristics. An example of blending is the addition of high alcohol wines to low alcohol wines. This practice is subject to precise limits imposed by specifications and legislation, both national and EU. For example ... "The blending between two or more musts or wines with different DOCG or DOC or IGT wines entails the loss of the right to use the original geographical reference for the product obtained, which may nevertheless be classified as IGT wine if it has the characteristics" (L.238/16 art. 38). Another type of blending is that practiced with fractions of the same wine, but of different vintages and duration of aging in wood. The purpose may be to improve a young vintage, or to "rejuvenate" an old vintage. In either case, the vintage to be listed on the label will be that of the wine subject to the ameliorative blend.
The wine resulting from the blending of several vintages is often called a cuvée and is used extensively in sparkling wine making under the classic method, where base wines of different ages are blended before refermentation. Exceptions are "vintage" sparkling wines, for which the blend, if any, must be made from wines of the same vintage (from different grape varieties or vinified by different procedures).
Also a blend could be an assemblage of different wines from the same the territory, like in the case of the Vignaioli di Radda Magnum 2018 that you see in the picture. In that case we blend all the Vignaioli di Radda producers in one magnum.