June 27, 2017
It could be environmental, uneven watering, pests or even natural aging of the flowers.
n the case of plants which have borne an abundance of bloom and then show signs of going out of bloom, a light pruning will produce another crop of flowers within 15-20 days. Here's the problem; people DO NOT want to cut plants back and WILL NOT cut them back as long as one pitiful-looking bloom endures. People who cannot discipline themselves to to shear old blooms periodically should not grow Verbena. After the first spectacular bloom display cut-shy people will be looking at ugly for the rest of the season and wondering why. Bloom removal is not tedious. Simply trim about a fourth of the plant's top growth, including old flowers but do not expose main stems, with a flexible line trimmer. Pruning removes old flower parts, shortens the plants and encourages branching which soon results in an even showier and prolonged display of bloom especially if you will fertilize and water after each cutback. Cutback will probably be required two or three times per season.
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