Preparing a Site

Select a Site with Good Drainage, free of weeds or choking grasses. If any exist, remove by pulling, tilling, or smothering with newspaper or plastic.  Use of herbicides is discouraged and should only be used if absolutely necessary carefully following label instructions. Loosen soil by tilling to a depth of 2-3 inches*, then rake smooth. Avoid fertilizing: this only encourages weed growth and will produce extensive leaf growth at the expense of blooms.
Control of Weeds
Weeds will choke out wildflowers unless removed.  Do this at and near the site you have chosen for wildflowers BEFORE you seed. After the wildflowers have germinated, it can be very difficult to distinguish flowers from weeds. For this reason, it’s best to wait until blooms appear, then simply pull up the unwanted weeds. This means waiting 8-10 weeks, so if you do recognize a weed in the meantime, obviously get rid of it.
*Avoid deep tilling.  Try to only disturb the top 2-3 inches of soil, then rake smooth.  Allow the weed seeds that have been exposed, to germinate, then hoe or hand pull them.  Leave them to dry out on the surface of the soil, to become an amendment for your soil.  Do not allow any weeds to seed out, pull or destroy all before they go to seed.  If you have time, repeat the process, by allowing another round of weeds to sprout up for subsequent destruction before planting your wildflower seedbed.  If you keep on top of the weed issue, you will eventually reduce the number of weed seeds that are left to germinate and your wildflowers will grow and fill in without competition.