For dedicated gardeners, here are suggestions from the California Assn. of Nurserym e n on what to do in the garden this week: * Keep after mildew problems on roses, lilacs and begonias by spraying weekly as long as the disease is evident.
* Hibiscus will soon be in full display. Visit a garden center and buy some to put in a sunny and warm, but protected area for flowering shrubs.
* Water tomatoes and melons deeply enough that water penetrates at least two feet down. Water shrubs deeply too.
* When planting around a pool area, choose plants that won't shed leaves into the pool. Locate plants where pool water won't damage them.