For dedicated gardeners, here are suggestions from the California Assn. of Nurserymen on what to do in the garden this week:
* Remember to keep the mower blades high two and two and one-half feet inches tall to give the lawn enough foliage to produce food.
* Roses suffer in the heat of August. Water deeply, mulch around the root zone if you want roses into the fall months.
* Plant garden mums now. There will be a good selection at your nursery.
* Feed tuberous begonias and fuchsias with 0-10-10 fertilizer.
* Divide and transplant bearded iris.