Regional Gardening Reports :: National Gardening Association

In the Garden:
Coastal and Tropical South
March, 2010
Regional Report

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Rambunctious loropetalum starts its show in the spring in the Southern Coasts region.

Flowering Shrubs

Shrubs that have showy flowers are not all alike, but their commonalities bear noting as they relate to caring for the plants. There are three types to consider.

Leaf Habits
One kind of flowering shrub is called "deciduous". That means the plant, such as flowering quince, drops all its leaves in fall. Others drop leaves in waves as new ones appear. They are called "semi-deciduous", and include loropetalum. Some are evergreen, adding new leaves each year, such as pittosporum. The ones that need our attention now are those that bloomed between February and late March. Though they may appear different, the basic steps to keeping all these flowering shrubs healthy for decades are the same. Most of the chores should be done just after the shrubs bloom in spring. Time is of the essence, since these plants begin the process of forming next year's buds within weeks of this season's blossoms.

5 Star Shrubs
The keys to flowering shrub success are soil, water, plant nutrition, pruning and pest control. Fortunately, when the first four factors are handled appropriately, insects and diseases are much less likely to be a serious issue for the shrubs. With few exceptions, shrub beds in our regions benefit from efforts to build up the soil continuously. When the mulch begins to break down, work it in to the top layer of the soil. Or, before putting down a new layer of mulch in spring, blanket the shrub bed with one inch of compost. Work that into the top layer and then apply the mulch. Water shrubs weekly in spring and summer unless thunderstorms prevail. It is best to soak the bed slowly and for a long enough time so that water percolates deeply. To grow steadily and bloom reliably, shrubs benefit from annual additions of nitrogen, phosphorus and potassium, plus trace minerals. Select a slow release product and use it in spring and summer on young shrubs; in summer on healthy older shrubs. Pruning flowering shrubs is a chance to be artful and shape the growth as you wish while at the same time encouraging future flowers. Take a few inches off all around each shrub, or shear them into a hedge, but prune flowering shrubs within one month after the blooms finish.

The primary pests of flowering shrubs are piercing and sucking insects like aphids, whiteflies, and scale insects. Healthy shrubs are bothered by fewer pests and less hospitable to a severe outbreak. Good air circulation around each shrub, good drainage, and good garden sanitation work to prevent diseases. Clean up fallen leaves and spray each shrub with horticultural oil in the winter to further reduce pest issues.

Great Plants
Our regions are home to a wide variety of spring flowering shrubs of all three types described, deciduous, semi-deciduous and evergreen. Along the Southern coasts, flowering quince comes first, followed by loropetalum and sparkleberry. Together, these three represent the past, present and future of landscaping in our regions, which will certainly focus more on native plants like sparkleberry. Both regions see flame azaleas, sweet viburnum and pittosporum used frequently. The native azaleas are deciduous, and are one of the few truly orange-flowering shrubs. Sweet viburnum, like the Chinese fringe shrub, often occupies the side yard at older homes. These big shrubs are green blobs except when they are in bloom, and then they are exceptional. Pittosporum can be had with leaves that are solid green or edged in cream. This evergreen looks neat all year, but the flower clusters are the icing on the cake. Cream-colored and arranged in pinwheel clusters, they match the strong form established by the shrubs. At the same time, gardens in the Tropics burst out with pink trumpet, a big shrub or small tree that stuns people who see it for the first time. No wonder so many people visit our regions in March, since some of these shrubs cannot grow further north and none are in bloom now.

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