Annual flowers add great interest to a garden. They may be short lived, but if you let them go to seed some annuals such as marigolds will keep coming back from year to year. If you want a great show of flowers with less work, planting annuals is the way to go.
Choose annuals that will grow well in your climate zone. You are planting these annuals in summer so they need to be able to handle the heat. Check the USDA Heat Zone Map to see where your climate falls to make the best decisions.
Prepare your garden for the annuals. Add compost or manure to the soil and work it into a depth of about 6 to 8 inches to improve the quality of your soil. If your soil is not well drained add sand as well and work it into the same depth. If you are just filling in space between perennials you do not need to bother with this step.
Plant annuals in the evening. This prevents them from having to sit through the hottest part of the day and allows them to settle in over night. Plant summer-blooming annuals as early in the summer as possible. Plant fall blooming annuals mid-summer.
Dig holes as deep as the containers and twice as wide. Space each hole about 8 inches to one foot apart, depending on the variety of plant. Space the holes at the bare minimum to get the most dense growth.
Place the annuals in the holes. Fill the holes with soil and pat down firmly.
Water your summer-planted annuals right away for about five minutes.
Mulch around the base of the annuals to help them retain moisture and prevent weed growth.