Hold the strawberry stain under cold, running water for several seconds until the water runs clear.
Pour 1 quart of cold water in a bucket. Add 1/2 teaspoon of gentle laundry detergent and 1 tablespoon of white vinegar. Stir the contents together with a spoon until well mixed.
Submerge the stain in the soapy mixture for 15 minutes before rinsing the dress clean with cold running water.
Lay the wedding dress on top of a thick, white towel. Blot any lingering strawberry-margarita stains with a white cloth dampened with rubbing alcohol. Rinse the rubbing alcohol off the dress with cold water.
Launder the wedding dress as you normally would.