A raised flower bed is a convenient way of gardening where the soil might be inadequate to support plants, such as on gravel, a paved surface or heavy clay soil. It lifts the ground level, providing better drainage as well as a surface that is easier to reach. You can control the soil moisture, the amount of nutrients and the kind of plants that grow in your raised bed much easier than an in-ground garden.
Design your raised flower bed by sorting the flowers by their height as well as by their width. Since space is limited, you need to be conscious of each flower's requirements. Mark the north end of the bed and plan to plant the shortest flowers on the south side and the taller ones at the north end so they don't block the sunlight.
Set your seeds or plants into the raised bed just as if you were planting a ground-level garden, setting them in deep enough to meet their planting requirements. If the weather is still chilly, place a row cover or any translucent cover over your plants to help hold in the warmth of the soil. Raised beds tend to get cold faster simply because they are exposed to more cold air temperatures.
Water your raised bed consistently. It will drain quickly and dry out faster. You can also add water-retaining gel capsules or perlite to the soil mixture to help it retain more moisture longer. A thick layer of mulch will also add more nutrients to the soil as well as conserve moisture from evaporating.
Rotate flowers of similar sizes within the raised bed. This will keep your bed looking fresh and attractive. Pull out dead or dying plants so they don't clutter the area.
Add fertilizers to help keep nutrients in the soil. You can use well-rotted compost, commercial fertilizers or mulches to help keep your plants in good health.