An overwhelming assortment of summer-flowering annuals is available at your local nursery. If you want an even wider choice of species and varieties, check in seed catalogs and online. From common marigolds to African daisies to more exotic flowering plants such as echinacea (purple coneflower, which you can grow as an annual), summer-blooming annuals add spirit and color to your outdoor landscaping. Don't forget native plants---although their flowers might not always be as large and showy as some hybrid varieties, they will certainly add interest to your yard and will help to attract beneficial insects and birds and contribute to biological diversity.
Planting Summer Flowers
Wait until after your final spring frost to plant summer-flowering plants outdoors. You can get a jump on the season by starting seeds inside, however. Sow your seeds in a nursery pot or flat that you have filled with potting soil---follow package instructions for correct depth and other details. Keep the soil moist and be sure to give it plenty of natural or artificial light.
Prepare your planting area(s) by first removing any weeds and then digging in about one shovelful of compost or well-composted animal manure for every 2 square feet of planting space. Be sure to research the needs of your plants: For example, if they require full sun, prepare a flower bed in an area that receives about 6 hours of sun each day.
Dig holes in your prepared garden bed that are slightly larger than your plant's nursery pot or their root system, if you grew them from seed. Then remove your plants from their pots or from the soil in which you started them and gently loosen the roots from the soil.
Place your young plants into the holes you dug and then backfill to the top of their roots with the soil you removed. Pat the soil down gently all around each plant and then water the plant well.
Apply a layer of mulch---compost, wood chips or sawdust all work well to help keep the soil moist and cool.
Water your newly transplanted plants about every other day to ensure that the tender root system does not dry out.
Fertilize if your plants need it, according to instructions for growing each variety. With good compost-rich soil, most plants do not need supplemental fertilizer during their relatively short life spans.