Garden News: Prune to help azaleas bloom

Azaleas are blooming.

You’ve probably seen azalea bushes so full of flowers you couldn’t see any green. And you’ve likely seen azalea bushes with many fewer flowers. What’s the difference?

“Pruning,” says LSU AgCenter horticulturist Allen Owings. “When azaleas are pruned improperly, you get fewer flowers.”

Like many spring-flowering shrubs, azalea bushes begin to make next spring’s flower buds in midsummer. If you prune after about the Fourth of July, you’re cutting away next year’s floral display.

“This is especially true if you want a highly trimmed plant,” Owings says. “If you use an electric clipper for a manicured appearance, you really need to do your clipping early and let the plant make buds during the summer.”

If a plant needs to be trimmed to remove tall shoots or branches, it’s best to use a hand shears and cut the branches below the plant’s canopy. The new growth will make the bush thicker and preserve the outer areas for next year’s display.

Keep in mind, however, that repeat-blooming azaleas, like the Encore varieties, produce blooms several times throughout the year — even in winter.

“If you need to prune this type of azalea, do it right after the first major spring bloom flush,” Owings says. “Then you won’t be diminishing your enjoyment of the repeat bloom periods.”

In addition to azaleas, other spring-flowering shrubs that should be pruned by late June or early July include spirea, mock orange, quince, hydrangea, weigelia, gardenia, camellia and viburnum.

You asked

Is there a way to get rid of the lichen growing on my crape myrtle trees? — Sylvia

Lichens are fungi and algae living together for mutual benefit. They do not harm our landscape plants, but they do indicate problems. Plants may need fertilizer, receive too much shade or have inadequate air circulation, or the area may be holding water or being over-irrigated. You can reduce lichens with fertilizer and regular care, along with improving air circulation and drainage. You can also spray with afungicide that contains copper. — Allen Owings

Got a gardening question? Write to GardenNews@agcenter.lsu.edu.