Hydrangeas are beautiful large leafed plants with flowers that come in variations of whites, purples, blues and pinks. These plants prefer morning sun with partial afternoon shade and need to be watered well to survive. Hydrangeas are sturdy plants, but do have some insects and pests that you should be aware of, such as aphids, leaf tiers, rose chafers and red spider mites.
Mist the leaves with water from the garden hose to get rid of aphids--a pear-shaped insect that harbors on the underside of the leaves.
Crush caterpillar larvae in the leaves if you notice leaf tiers on the hydrangea. These pests bind the leaves together for protection. If they begin to turn into small, green caterpillars with brown heads, remove them from the leaves and throw them in a bucket of soapy water until they are all gone.
Spray the leaves with water every day for three to four days with water from the garden hose if leaves are turning brown on the edges or look like they are burned. This is most likely from spider mites.
Apply a solution of insecticidal soap to the leaves for heavier spider mite infestations.
Fertilize the hydrangea plant with fish emulsion and compost to encourage certain fungi that eat worms and keep pests away.