Choose a site that gets plenty of sun and protection from wind. To improve soil texture, work compost or other organic material into it; if necessary, correct the soil pH by adding peat moss to diminish excess alkalinity or lime for excess acidity (flowers grow best in sandy loam with a neutral pH). Several weeks before planting, force out weeds: Irrigate the soil, wait for weeds to emerge, then hoe them out; repeat at least once.
Decide how many plants will fit in your space. If you don't have room for the entire 5- by 12-foot bed described above, you can adapt the idea to fit your space by using fewer plants.
Outline the boundaries for each variety by marking the soil with gypsum (A).
Sow seeds according to package instructions. Water soil and keep it moist until seedlings emerge. Thin seedlings as directed on seed packets (B).
If rainfall is scant, apply about an inch of water per week. Don't be shy about picking blossoms; it will only spur more production. Clip any faded blooms you missed (C).