Per the Timectin product label the instructions for mites on ornamentals are as follows
Pests Controlled at 4 fl. oz. Timectin™ 0.15 EC T&O Insecticide/Miticide/100 gallons:
Mites including European Red Mite, Twospotted Spider Mite, Carmine Spider Mite, Southern Red Mite, Spruce
Spider Mite, Tarsonemid Mites (Cyclamen and Broad Mites), Eriophyid Mites (Rust and Bud Mites)
Apply when mites first appear. Make repeat applications as necessary to maintain control.
This equals to down to about .04 oz/gallon of water for a smaller application.
Timectin 0.15 EC Insecticide Miticide is not labeled for the control of nematodes, there's a possibility that it could be effective if the nematodes were applied to the treated area at the same time. AzaGuard Insecticide Nematicide is labeled for the control of many different insects as well as nematodes. Another option is Monterey Nematode Control but it's only labeled for home gardens and lawn parasitic nematodes.