Advice from the Help Desk of the UC Master Gardener Program of Contra Costa County
Help Desk Response: Thank you for contacting the Help Desk with your questions and concerns about your Bush Anemone plant with yellowing leaves.
Once established, this is a very hardy low-water-use plant, but even these varieties need extra water usually for the first several years while becoming established. However, yellow leaves can be a symptom or either under or over-watering. You mentioned that there is only one one-gallon dripper for 40 minutes a week, which would give the plant less than one gallon a week. Even for a young drought-resistant plant, this may not be enough, especially since it was planted this spring spring and in sandy soil. Also, one drip emitter would only be watering one side of the root ball. You can check on the moisture in the root area by carefully digging down beside the plant with a trowel or your hand, to feel for moisture, or if you have a soil moisture meter that can also be used. When you water, you want to wet the whole of the root ball and then let it dry out between waterings. If you want to continue to use drip, a circle of inline emitter hose around the plant or at least 2 emitters on opposite sides of the root ball would provide more even moisture than a single emitter.
http://ucanr.edu/sites/scmg/ Plant_of_the_Month/ Carpenteria_californica/.
The paragraph on Cultivation provides some good advice on getting your Bush Anemone back in good health and watering appropriately for the first several years. (The pictures in this blog post were also copied from the Sonoma County Master Gardener article in the link.)
I hope this is helpful, and that your plant will do well.
Follow-up response from the client: Thanks so much for this information. I have mostly drought tolerant plants but I always find that first year or two a big question mark. I have a newish lavendar that seems to be thriving with no water at all - and then this which seems to need more. And I love this plant when grown, so I don't want to lose it! I'll give it more water until the rains (hopefully) begin.
Help Desk of the UC Master Gardener Program of Contra Costa County (SMW)
Note: The UC Master Gardeners Program of Contra Costa's Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523. We can also be reached via telephone: (925) 646-6586, email: firstname.lastname@example.org, or on the web at http://ccmg.ucanr.edu/Ask_Us/ MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (http://ucanr.edu/blogs/CCMGBlog/).