Spider mites are common destructive insects that plague many types of flowers and vegetables, including hydrangeas. They often thrive in warm, dry climates and will eat away at your plants until they are brown, deformed, dried out and nearly dead. Getting rid of the pesky insects can be tricky, but it's important to eliminate them in order to ensure the health of your garden. The best way to get rid of spider mites on your hydrangeas is to keep them moist and to use an insecticide.
Spray the hydrangeas with cool water. The force and weight from the water may be enough to knock the mites off and prevent them from coming back.
Keep the soil moist at all times. Mites prefer dry, hot conditions, so constant moisture will make the plant less appealing to the mites.
Spray the plant with an insecticidal soap to kill off any remaining mites. Repeat the process once a week until all signs of mites go away.
Collect as many ladybugs as you can find and set them free near the spider mites. Ladybugs feed off of small pests such as spider mites but will not harm your plants.