Any flower will grow in a raised bed. Those that are a bit fussy about soil requirements will flourish. Others that prefer poor soil, like wildflowers, will grow lush and green but without a lot of blossoms. Raised beds are easier to weed because there's less bending over. The soil stays fluffy and loamy because no one walks on the bed, compacting the soil.
A raised bed is excellent for tall flowers being used as a privacy screen or to block unwanted views. The height of the raised bed boosts the flowers an additional 12 to 24 inches or however high the bed is. Very tall flowers such as sunflowers and hollyhocks, which grow to 6 to 8 feet, naturally become tall enough in a raised bed to become a living screen. Other tall flowers include delphinium, butterfly bush, cleome and verbena.
Vines and Climbing Flowers
Attaching lattice work to the inside or outside of one side of a raised bed provides support for climbing flowers. Flowers such as sweet peas, clematis, trumpet vine, snail vine and California lilac will clamber up the lattice work.
Flowers like bougainvillea, climbing roses and lilac will require a sturdier support than lattice work. Use them over an arbor at the back of a raised bed.
Treat a raised bed much like you would a container garden. In an island bed, plant flowers that grow tall in the middle. Surround them with medium-sized flowers. Plant shorter flowers to edge the raised bed. Plant flowers that cascade on the sides of the bed. Contrast the shapes of the flowers as well as the height. Try cosmos which grows to 4 feet in the center of the bed. Plant a rose bush on each side of the cosmos. Surround them with pansies in the spring, geraniums in the summer and chrysanthemums in the fall.
Vary the shapes and sizes of the flowers as well. Baby's breath has tiny white blossoms floating on airy stems. Bachelor's buttons are puffs of blue, white and pink about the size of a large marble. Gerbera daisies are large flat, many-petaled flowers. Lilies are trumpet-shaped and from 5 to 6 inches long.
Many flowers are edible, but some are poisonous. It's a good idea to segregate edible flowers from the others. A raised bed allows that measure of safety. Edge the bed with veggies to harvest along with the flowers. Bright lights chard comes in red- and yellow-stemmed leaves as well as white. Curly kale with its ruffled olive green leaves contrasts nicely with vividly colored flowers. Beets have red leaves that are edible as well as the root portion.