Broad-leaved rhododendrons, spring flowering lilac and summer flowering hydrangeas are just a few examples of favorite flowering shrubs. Fortunately for gardener enthusiasts, there is a flowering shrub suitable to every climate, landscape and soil type. Components crucial to flowering shrub care include soil preparation, proper planting depth, water requirements, fertilization and pruning. Basic care routines will be similar between shrubs, but particular species and cultivars might require specific care methods. Planting can be done in fall or spring, depending on your climate zone and the availability of your shrub of choice.
Choose a flowering shrub that will attain a height and spread in proportion to your planting site. Also consider the available light and soil drainage qualities of the area. Although soil can be improved, light levels can cause issues with growth for the life of your shrub.
Prepare the soil by tilling to a depth equal to the height of the shrub's root ball. Cultivate the soil several feet in diameter around the planting zone. Add organic matter, such as composted pine bark, at a rate of 20 percent of the soil volume. Incorporate well with the tilled soil. Dig a hole for the shrub, leaving the base of the hole undisturbed.
Loosen a container-grown flowering shrub and gently slide it out after the hole is prepared. Burlap-covered root balls should be opened and inspected for root wrapping or binding. If the root ball looks bound, use a clean knife and make up to four vertical cuts at regular intervals around the exterior of the ball. Gently loosen the freed roots so they will spread freely once planted.
Set the root ball in the hole, resting on the solid base of soil at the bottom. Gently backfill around the roots, firming as you add layers to the top. The top of the root ball should rest just under soil level. Create a water ring by mounding soil around the edge of the root-ball zone to supply water to the establishing roots.
Mulch the area with up to 2 inches of pine bark to retain moisture and discourage weeds.
Water the shrub at the soil level until it is evenly moist. Clemson University Cooperative Extension experts suggest that watering frequently for the first month, up to once a day, can be very beneficial for root establishment. Do not allow water to pool over the bed or lay stagnant, however, because diseases spread readily in these conditions. Avoid watering over foliage because this also promotes disease.
Fertilize your flowering shrub in early spring. If you just planted, use a balanced, slow-release fertilizer at the rate suggested by the manufacturer. Apply with a broadcast spreader in an even manner over the root zone of the shrub. Water well to facilitate soil contact. Avoid fertilizing after a fall planting in zones where your shrub will go dormant. Fertilizer might promote growth that will fail to harden off and can damage the shrub.
Prune flowering shrubs based on the type of shrub, its age, the location and desired shape. Few shrubs can tolerate shearing, or cutting a flat plane across the top of the growth. Opt for spring thinning or heading for more mature shrubs that flower on new wood or the current year's growth. Choose midspring or summer pruning, just after flowering, for mature shrubs that flower on old wood or last season's growth. Thinning is a process that removes up to a third of the oldest canes to the ground, producing a more open shrub. Heading removes the uppermost growth of selected branches at the first growth node to encourage branching and a better shape. Pinching off is a spring or after-flowering method used for young shrubs to encourage branching, but be sure you know when your shrub flowers to avoid removing precious buds.