Should I get professional treatment of red spider mites on my cedar trees? Do you recommend deep root feeding of cedars?
It is certainly possible for the home gardener to treat a spider mite infestation on cedars. As a first attack try a strong spray of water to dislodge the mites and destroy their webs and eggs. This should be repeated regularly until you notice a decrease in the spider mite population. If this is not effective, applications of insecticidal soap may be more successful. Speak to your local nursery about whether there are particular varieties of insecticidal soap recommended for evergreens.
Under normal conditions it should not be necessary to give your cedars deep root feeding. However, given that your trees may not have been getting sufficient water in recent years, the radical pruning that has been done and the stress caused by the mite infestation it is something that you might consider.