Standard disclaimer: I am not a lawyer. If I were, I'd shoot myself as a public service. B-)

That out of the way, I have 2 answers for you. Unfortunately, they are contradictory.

1) Yes, it's legal so long as you have it recommended by a licensed doctor.

In 1996, Prop 215 was passed and became Cal Health & Safety Code 11362.5 (aka the Compassionate Use Act), which ammended the state's existing prohibitionist anti-marijuana law (CHSC 11357). The entire law is available at www.leginfo.ca.gov/cgi-bin/waisgate
but most importantly..

CHSC 11362.5(b)(1)(a):
"(A) To ensure that seriously ill Californians have the right to obtain and use marijuana for medical purposes where that medical use is deemed appropriate and has been recommended by a physician who has determined that the person's health would benefit from the use of marijuana in the treatment of cancer, anorexia, AIDS, chronic pain,
spasticity, glaucoma, arthritis, migraine, or any other illness for which marijuana provides relief."

So you are legal under state law, so long as your cultivation is only for your personal medical use, and so long as that use is recommended to you by a state-licensed doctor. Does "recommended" mean a written prescription? Nope! Because right below it we have

CHSC 11362.5(d):
"d) Section 11357, relating to the possession of marijuana, and Section 11358, relating to the cultivation of marijuana, shall not apply to a patient, or to a patient's primary caregiver, who possesses or cultivates marijuana for the personal medical purposes of the patient upon the written or oral recommendation or approval of a physician."

The Compassionate Use Act gutted both the prohibitionist anti-possession law (CHSC 11357) and the prohibitionist anti-cultivation law (CHSC 11358). All you need is a licensed doctor to say "Yeah man, s'cool!" and you're legal under state law to grow for your own personal medical purposes.

At the county level, the only relevant law I can find is:
ah fuck, that server just went offline. Weird. Well anyway, it doesn't say anything really. Just proclamations and general directives to county staff to "develop policies".

If you're talking about growing inside of city limits, then we must also reference city law:
SCMC 6.90.040 Permissible medical marijuana cultivation.
nt2.scbbs.com/cgi-bin/om_isapi.dll

6.90.040PERMISSIBLE MEDICAL MARIJUANA CULTIVATION.
" 1.All cultivation of marijuana for medical purposes performed by persons in possession of a growing certificate shall be lawful and shall in no way be subject to criminal prosecution when said cultivation is conducted solely for the personal medical purposes of qualified patients in accordance with California Health and Safety Code Section 11362.5."

Here our City Council tried to re-inforce the CUA within city limits, but only on the condition that the grower was growing on behalf of a city-recognized medical marijuana association, as clarified here:

6.90.020 RECOGNIZED STATUS OF MEDICAL MARIJUANA PROVIDER ASSOCIATIONS, QUALIFIED PATIENTS AND PRIMARY CAREGIVERS.
...
3.The city of Santa Cruz shall recognize valid "growing certificates" issued by recognized medical marijuana provider associations.

Note that this does not make it illegal to grow without a certificate - it simply gives extra protection to those who do grow with a certificate. Those who grow for their own personal use are, I believe, left only with state law to contend with as detailed further above.

SO - is it legal? Appears to be, as long as you have at least a doctor's verbal okay-dokey, you only grow as much as the doctor recommends for you, and you never sell, trade, or give it to anyone else. i.e. you treat it like any other prescription drug.

That's my #1 answer for you. Now the bad news.

2) It doesn't matter if it's legal, the fucking cops don't care. They'll raid you anyway, steal your stuff, destroy your stash, and walk away laughing. We aren't exagerating when we say they're out of control.

However, if you ask a slightly different question, we can get somewhere. Rather than asking "Is it legal?" - an antiquated and meaningless concept in today's corrupt (in)justice system - if you ask "What are the different agency's criteria for raiding a garden?", now we have something to work with.

For example.. if you have 99 or fewer plants, I understand the federal agencies like the DEA will at worst just report you to the local cops and forget about it. You're too small for them. (They want the big growers who are more likely to have expensive cars, boats, and homes that the cops can steal and sell for profit at govt auctions.)

Sherrifs, CHP, State Troopers, they all generally don't care if you're inside city limits. They let the city gestapo stalk that turf.

So here, then, is the magic bullet. Someone needs to call Santa Cruz PD, and ask them NOT what is legal - they'll dodge that claiming "We don't interpret the law, we just enforce it. Consult with an attorney." What you ask them is for their official departmental guidelines or criteria on when a marijuana garden justifies - in their mind - arrest of the grower and/or "confiscation" (read: theft or destruction) of the garden.

Unfortunately, what I hear is that these criteria have been left intentionally vague and "up to the officer's discretion". Cops actually argued FOR this, and against explicit standards. They cried that strict rules would unfairly put patients at risk, and that each case should be evaluated on its individual merits.

Very "compassionate" of the cops, until the reality check bounced. How did each case become evaluated on its own merits? By each cop playing doctor and "determining" in each case whether the person he was raiding had "too many" plants for that person's specific medical condition.

Yeah, suddenly cops pretending to be qualified to make medical judgements. Hell, pretending to be objective at all.

The result has been that no matter how few plants you have, the cops will claim to evaluate your medical condition and claim that you don't need as many plants as you have and that therefore you're growing for non-medical purposes.

And bam, you're busted.

So what's the solution? I mean besides waiting for modern genetics to hit the test tubes and somehow breed us the world's first honest cop? I wish I knew. So do a lot of people.

The whole drug war, from top to bottom, has become one great big unending government-operated crime wave against people who are just minding their own business.

America, land of the free? Not anymore, not entirely. And it gets worse every year.

-Van