When you are designing an annual garden, you are only limited by your imagination. Annuals--flowers with only one blooming season--come in every shape, size, color and texture. How you put them together depends on your taste, your outdoor decor and your available sunlight.
Visit a few garden centers to get an idea of what plants are right for your growing zone and what is available. Early in the season, the selection of colors and plants will be greatest. Some annuals like zinnias or snapdragons sell quickly and might not be as readily available in just a few weeks. Take note of growing space, colors and plant height in a notebook, if needed. Know your sun needs and plan accordingly.
Prepare your bed. Whether sowing annual seeds after the danger of frost or planting seedlings, your space needs to have loose, rich soil. Till it or hoe it until it's a fine powder, adding in organic material like compost or manure. You might wish to take a garden sampling to your local extension office for free testing. The experts can tell you what you need to add to your soil for optimal growing conditions.
Lay long pieces of rope or garden hose through the garden to plan the flow of the plants. Using movable material like this helps you make changes easily.
Place any large items of decor in the space. Things like birdbaths, bird feeders, watering cans, etc. add interest and can really make a garden pop. An old wooden kitchen chair or old ladder can become a trellis for annual climbers like morning glories.
Use a marking aerosol spray to plan where plants are to be placed. The best designs incorporate odd numbers--consider planting like plants in groups of threes or fives.
Place those plants that grow the tallest at the back of garden spaces along walls, fences or other spaces where the garden will not be accessed on all sides. For beds that can be seen from all sides like those placed in the middle of properties, consider placing your tallest plants in the middle and cascading your way down in height from all sides.
Continue placing flowers based on height from tallest to shortest, based on expected growing heights information on the planter spikes that came with the flowers. Follow the directions on spacing needed as well to give each plant the opportunity to grow correctly.