Do you mean the pots to be individual table centerpieces? Unless it is one of the greenhouse or florist hydrangeas that are grown specifically as a flowering gift or houseplant, hydrangeas seldom bloom at a very young age or a size that would be suitable for a table centerpiece. You can certainly find small, 1G sized plants available at nurseries and garden centers in season but there is no guarantee that they will bloom unless you can see buds already present. And that's not all that common. Larger, more mature plants could very well produce blooms in time for your wedding but their size might make them awkward as a centerpiece. And starting them this spring from a cutting is pretty much a no-go for a flowering plant by August. A seed started plant is out of the question for several years.

This may not be feasible in terms of economics but contacting a florist or garden center in your area who can order ahead and bring in the greenhouse grown plants in the appropriate size and in bud or bloom in time for the wedding may be your only guarantee. These plants are manipulated by the growers to bloom heavily at a very young age and small size and at virtually any time of the year you want.