Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk with a question about overwintering Gerbera Daisies. Gerberas are perennial plants but are often treated as annuals. They need regular deep water and do best in rich, well-drained soil. They should be fertilized monthly during the bloom period. They do well in full sun, but in hot areas such as most of East County, they need partial shade. If you have a nice clump of them, you must be doing something right!
They should overwinter in the ground just fine in East County. According to Sunset Western Garden Book, they can be grown as perennials in zones that get even colder than your Zone 9. As long as the soil drains well and doesn't become waterlogged when it rains, your gerberas should be OK.
Mulch is almost always a good idea. It protects the soil and helps maintain even moisture levels. Just make sure you keep the mulch a couple of inches away from the plants' stems to avoid rotting.
Please let us know if you have more questions.
Help Desk of the UC Master Gardener Program of Contra Costa County (SEH)
Notes: Contra Costa MG's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone: (925) 608-6683, email: email@example.com, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.ignore.edu/HortCoCo/ You can also subscribe to the Biog.