Characterized by moderately vigorous, high yielding vines, Merlot ripens in middle season, producing fruitier, softer, and more delicate wines. Merlot was considered a minor grape variety in Bordeaux during the nineteenth century because of its tendency to shatter. Perhaps because of this factor it was rarely planted in California at that time. After Phylloxera the development of new rootstocks mitigated the shatter. (Shatter happens during flowering, instead of the fertilized flowers on a cluster developing into individual berries, a percentage of the flowers fall off leaving a sparsely populated grape cluster.)
Merlot is now the widest planted grape variety in Bordeaux (22,200 Hectares or 49% of red grape plantings). Recently in Bordeaux, planted acreage in Merlot expanded so rapidly that the variety threatened to displace much of the Cabernet vines. Legislation was required to stop its proliferation. In California, Merlot is the fastest growing varietal wine. The rapid proliferation of the variety on both sides of the ocean is due to the changing trends in wine consumption where softer, youthful and fruitier wines are admired and where fewer producers and consumers are willing to wait for a red wine to age.
Merlot makes wines that have good body, but are softer and rounder than Cabernet Sauvignon. Bud break and ripening in Merlot is earlier than Cabernet Sauvignon. While Merlot does well on the best soils; it will produce wine superior to Cabernet Sauvignon on poorer drained soils or heavier soils. For this reason the vineyards in Bordeaux that have areas of heavier soils seem to have evolved with higher percentages of Merlot. Merlot finds its highest use in Pomerol and St. Emilion. Ch. Petrus is entirely Merlot. Its soils are clay and sandy clay. There are a lot of clones of Merlot around, at least 15 certified in France.
In Bordeaux it is planted on three de-vigorated rootstocks. Vigorous rootstocks should only be used in special conditions due to the risk of shatter.