For dedicated gardeners, here are suggestions from the California Assn. of Nurserymen on what to do in the garden this week:
* Divide overcrowded perennials this month.
* For exquisite shade color this spring and summer, begin tuberous begonias indoors in moist peat moss. Do not bury the tops. Plant outside once the frost is past.
* Place three inches of mulch around trees, shrubs and flower beds to keep weeds under control. Keep the mulch away from the trunks of trees and shrubs as well as the stems of bedding plants.
* Plant a grapevine on fence or arbor for shade and sweet fruit this summer.
* Remove old flowers on camellias and azaleas to reduce the chance of petal blight.