Ask GreenState: How do I test my cannabis for potency and mold


Commercial legalization is just a little over 90 days old in California, and readers have a bumper crop of questions. We attempt to tackle them in our series Ask GreenStateGot a question for Ask GreenState? Email cannabis editor ddowns [at]


I want to test some product who would you suggest I use? I was given something. Should I worry about mold or other things? I would also like to know something about what I grew.



Yes, I am definitely on the lookout for moldy homegrown. It’s prevalent. Good thing the human nose has tens of thousands of years of practice picking up any traces of rot and decay. Trust your nose. If it doesn’t smell 100 percent awesome, don’t smoke it.

As for testing services: yes, commercial labs like Steep Hill in Oakland do test personal gardeners’ crops. Tests can run about $95 to test for potency and mold. A potency test determines how much THC, the main active ingredient in cannabis, is in the sample. A microbial test usually involves culturing a sample on an agar plate and seeing if lots of microbes grow. If the microbe count is over a certain limit, the sample is deemed a “fail”. You don’t want to be smoking anything that has lots of mold or fungus spores on it. They can end up in your lungs. We reached out to our best lab contacts and here’s what else they said. . . .

From Josh Wurzer at SC Labs: “We do offer testing for anyone with a medical recommendation. [The pricing] obviously varies depending on the tests you request and the volume you do. [Call for pricing.] Our promised turnaround time is five business days, however we strive to do much better than that and usually do. Our lab runs two shifts seven days a week. They can contact us by calling 866-435-0709 or emailing They do need a medical rec.

From Jeffrey C. Raber at The Werc Shop in Southern California: Yes, testing for that is allowed and can be done. [Tests run] around $60/test type. Turn around depends on when the sample is delivered and what tests are needed to be done but usually less than a week. We made sure the law included that home growers could test with the labs!

From Steep Hill Labs in Northern and Southern California: “We offer testing for individuals as long as they have a medical card. Potency testing can be done on dry, market-ready flower. Express Potency testing is only $50, which requires two grams of flower. Express Potency gives same day results. Standard Potency is better for figuring exact THC:CBD ratios, takes a little bit longer (5-7 business days), and costs $75 — one gram of flower is required. For cooks and other creatives, we offer testing on edibles, topicals, beverages, oils and tinctures. To set up an account, contact or give us a call at 510-562-7400.

I think the issue remains what will individual testing look like after July 1st. We all look to the State of California’s BCC for response.

And from Scott Parker at CW Analytical: We can absolutely help your readers get their cannabis tested. Turn around time is between 5-10 days at the moment depending on the test requested. The microbiologic screening being the most time-consuming as we have to grow out the cultures. ​Cost for a potency analysis is $90, and microbial screening ​run from $25 for just an APC (Aerobic Plate Count) to $200 for all available screenings. We also offer special pricing for qualified patients. For ‘in process’​ or “non-compliance” ​testing, we accept samples via walk-in at our location in Oakland, Monday-Friday, 10am-5:30​ ​pm.​ If any of your readers would like more information they are welcome to give us a call at (510) 545-6984.

By: David Downs, Green State