CannaGLAP
Grow cannabis in San Leandro, CA
Growing cannabis in San Leandro: a garage that stays mild and breathes damp air
San Leandro hands a garage grower an easy thermostat. The Oakland airport station, 3.5 miles away and 6 feet above sea level, averages about 3 freezing nights and about 6 afternoons at 90°F in a whole year. Summer highs run 71°F to 74°F from June through October, and winter lows sit near 42°F.
A space that rarely bakes or freezes is easy to trust, and that is the risk. A garage breathes the same air as the street, and that air averaged 78 percent humidity in August 2024. When temperature looks after itself, who watches the number that does not?
Adults 21 and over: yes. Plant limit: 6 living plants per private residence, however many adults live there.
Locked space, not visible from a public place; cities and counties can set reasonable rules for indoor grows (but cannot ban them) and may ban outdoor grows; a landlord may prohibit growing on a rental. Source: Department of Cannabis Control; conditions: Prop 64 text as passed in 2016 (H&S Code 11362.2 and 11362.45). Local rules (landlords, HOAs, city codes) can add more; this is a summary, not legal advice.
A San Leandro garage or spare room, season by season
Read the outdoor humidity row as your garage's row. A closed, heated bedroom dries its own air, but an uninsulated garage off East 14th or a back unit near downtown runs close to the outside air. In 2024 that meant 72 percent in June and 71 in July, then 78 in August and 76 in September, the dampest of the June to October months. A tent flowering through late summer there needs a dehumidifier sized for the whole garage and a fan pushing air under the canopy.
Heat barely enters the plan. September is the warmest month at the station, with an average high of 74°F and about 2 afternoons at 90°F, the most of any month. On those few days, a tent that runs its light at night stays cooler.
Cold is the garage's other gap. December and January lows average about 42°F, and the average night stays at 45°F or above only between February 20 and November 22. A bare slab can chill roots once the lamp clicks off, so set pots on a rack, give young plants a seedling mat, and let the light run through the coldest hours from December into February. January's 84 percent outdoor reading fades in a heated room; it matters in a garage or spare room that stays cold and damp.
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 58 | 60 | 63 | 66 | 68 | 71 | 72 | 72 | 74 | 72 | 64 | 58 |
| Avg low °F | 42 | 45 | 47 | 49 | 52 | 54 | 56 | 57 | 56 | 51 | 46 | 42 |
| Humidity % | 84 | 72 | 71 | 78 | 76 | 61 |
Highs and lows: NOAA 1991 to 2020 normals, Oakland Metro International Airport station (3.5 miles away). Humidity: Open-Meteo historical model data, average daily humidity in 2024, for the months shown. Planning averages, not a forecast.
Outdoors in San Leandro
State law caps a private residence at 6 living plants, no matter how many adults share it, and wants them locked up and hidden from anyone in a public place. Local governments may restrict or forbid growing outside, so read San Leandro's code first. Where it is allowed, sow indoors from March 4 through March 18 and move plants out from April 15. Nights do not average 50°F until April 25, so young plants may start slowly.
The finish is where timing pays. Humidity averaged 76 percent in September 2024 and 61 in October, and nights hold a 50°F average until October 22. A plant that ripens in the first three weeks of October finishes in the drier air; one that finishes early, in September, pays for the head start with damper weeks. Check inside the fattest colas after damp mornings.
| Frost | Rare: about 2.6 freezing nights a year |
|---|---|
| Nights stay 50°F or warmer | Apr 25 to Oct 22 |
| Start seeds or clones indoors | Mar 4 to Mar 18 |
| Move plants outdoors | Apr 15 or later |
A quiet grow along the BART corridor
In an apartment along the BART corridor or a house off East 14th, a neighbor may be a wall away, and a Wednesday or weekend farmers market is the kind of place you might meet another grower. A garage fan humming all August gets noticed, and encryption cannot hide noise or the smell of a flowering plant. It keeps the record to you: what saved a late summer run, and what came off in October.
Canna GLAP scrambles that grow journal on the phone itself, before a single entry uploads. Someone breaking into our servers would turn up grow records in coded form, with no key that opens them. A roommate or a landlord sees your notes only if you hand over the phone.
What is encrypted: your plants, notes, photos, feed logs and harvests. What is not: account details (such as your email, name and plan), a grow name or town if you type one, your team, and your sensors' names. The full list: what a hacker would get.
Questions growers in San Leandro ask
Does San Leandro get frost?
Rarely. The Oakland airport station, 3.5 miles away, averages about 3 freezing nights a year, and December and January account for most of them.
Do I need a dehumidifier for a garage grow in San Leandro?
For flowering, usually. A garage takes in outdoor air, and that averaged 78 percent humidity in August 2024 and 76 in September, damper than ripening buds like.
When can I plant cannabis outside in San Leandro?
From April 15, if the city allows outdoor plants, after starting seeds March 4 to March 18. Nights only average 50°F from April 25, so plants may grow slowly at first.
Growing near San Leandro
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