The key to building an attractive and productive flower bed is planning. While you can build a flower bed at any time of the year, it is best to start a flower bed in the fall. This way, the organic material you added will have time to mature, beneficial organisms can congregate and any amendments that you have added will have time to adjust your soil's pH. A garden built the day of planting will still grow flowers, but it will not reach its full potential for roughly one year.
Mark the border of your garden with a thick line of flour.
Remove any existing grass or weeds. If you are removing grass over a large area, then you may want to use a sod cutter. Otherwise, a flat shovel works just as well. Simply dig a few inches underneath the soil and be sure to remove any visible roots along with the grass or weeds.
Turn the soil. If you are building a large flower bed, then you may want to use a rototiller. Otherwise, a shovel will do the job. Start at one end of your garden bed and dig to a depth of 1 foot and then turn the soil over. Remove any bits of debris or rocks and loosen any clumps of soil that you encounter along the way.
Have a sample of your soil analyzed. Order an online soil testing kit, contact your local county extension office or ask if the service is offered at your local garden center. The analysis will let you know the pH and nutrient content of your soil. Depending on the flowers that you intend to plant, you may have to amend the soil to change its pH level.
Spread a 4-inch layer of aged compost and any necessary amendments over the upturned flower bed. Then use your shovel to turn them into the soil to a depth of 1 foot.
Smooth the soil with a garden rake.
Leave the soil to mature over the winter. If your area experiences freezing temperatures in winter, cover the flower bed with a 3-inch layer of organic mulch.
Plant your flowers in spring.