Drought Changes the Rules for Roses
Tom Carruth, Rose Curator at Huntington Botanical Gardens in San Marino, oversees the care of more than 2500 rose bushes. He’s developed rule-breaking hacks to keep plants flourishing during a drought. The dry heat has introduced a heat-loving predator called “chilli thrips” from South Central Asia. The adults are so small they can fly 60 feet in the wind currents. Here are some of his measures to save your roses:
Water from Above
The old rule has been to water roses at their base to reduce mildew and other diseases, but that’s more for wetter climates. Carruth now uses sprinklers at least 3 feet high to water in the early morning twice a week for about 20 minutes.
Get Rid of Old Mulch
It used to be that old mulch was covered by new, but Carruth says to strip rose beds clean every January, removing every leaf from the plants and all the old mulch to eliminate pests and disease. Be sure to apply 3 to 4 inches of new mulch to discourage weeds and keep the rose roots cool. He recommends using large chunk wood bark and avoiding mulches that contain pine, eucalyptus, palm or bamboo. He says, “If you notice those trees, things don’t like to grow under them.”
Go Organic and Spray
Spray with Spinosad, a natural insecticide readily available under many brand names. Because it is toxic to bees, he sprays during the hottest months and late in the day when bees are less likely to be out.
Feed the Plants
After the roses are pruned in January and new growth begins to emerge in February, he feeds all the roses with Scott’s Natural Lawn Food, an organic granular lawn fertilizer. Also spray rose plants with organic liquid fertilizers ever six weeks in the early morning to harden the foliage and help the plant withstand drought conditions.
—Bill Walkup
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