A raised flower bed offers gardeners several advantages compared to planting flowers directly in the unamended ground, according to the University of Missouri. For example, it allows the gardener to grow vegetation on top of poor soil and breaks the landscape into various heights, creating a more filled-in appearance while bringing the flowers closer to the eye. Several management and construction tips can help you maximize the benefits of raised flower bed gardening.
For a stable raised flower bed, construct the flower bed deep and wide enough so it doesn't easily wash away. The University of Missouri recommends constructing the raised bed by stacking a wall of bricks or similar material at least 12 inches high. Raised beds created by simply mounding the soil without using supporting edging should be at least 3 feet across and 12 inches deep at its peak where you'll plant the flowers.
The bedding soil itself should be composed of organic, rich soil to ensure vigorous and colorful flower growth. For the best results, use soil that's 3 parts garden loam and 1 part aged compost, according to Texas A&M University.
The best shape for your raised flower bed is largely an issue of personal preference. Though raised vegetable beds are usually rectangular for easy access to the bed's vegetation, ornamental flower beds are often curved or formed in creative shapes to match the style and shape of your yard, according to Texas A&M University.
Raised beds lose moisture faster than flower beds that are flush with the soil because more of the soil is exposed to the air and heat, according to the University of Arizona Master Gardener Manual. Prepare to water the bed more frequently than you would a flat bed, especially during warmer months. Mulch can help lower the watering needs of the bed by reducing evaporation. The University of Missouri recommends spreading a couple inches of organic material, like straw or shredded leaves, on top of the bed's surface.
Flowers in raised beds need fertilization just like those in flat beds, according to the University of Missouri. The university recommends using a general all-purpose fertilizer like a 10-10-10 product, spread onto the flower bed at a rate of approximately 1 lb. for every 50 square feet of bedding area. Fertilization frequency depends on the specific feeding needs of the types of flowers you're raising.