CannaGLAP
Grow cannabis in San Lorenzo, CA
Growing cannabis in San Lorenzo: damp late summers on days too mild for cooling to help
San Lorenzo's late summer is damp and mild at once. In 2024, humidity rose from 71 percent in July to 78 in August and held at 76 in September. Afternoons stay pleasant through it, in the mid to upper 70s.
In a hotter town, an air conditioner pulls water out of a grow room as a side effect of cooling. Here, on days this mild, it would seldom switch on. So if cooling will not dry your flower room, what will?
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 Lorenzo grow room in mild, wet air
The Hayward Air Terminal station, 1.9 miles away, puts more of the year's few hot afternoons in September than in any other month, about 3. A typical August night falls to about 58°F, so an exhaust fan usually has cooler air to draw on. An air conditioner, if you own one, dries only while it runs, and on these mild days it mostly sits idle.
So give the drying job to a dehumidifier on a humidistat (a switch that runs it to hold a set humidity). Size it for the room the tent breathes from, not just the tent: a garage, or a room with open windows, takes in outdoor air near that August reading. Keep it running at lights-off, when the tent cools and its humidity climbs, and thin the inner leaves so air reaches the center of each plant.
Indoors, you can also move the calendar. In 2024, October's air averaged 61 percent, far drier than August's. A run flipped to flower (switched to 12-hour days) in late summer rather than early lands its final weeks there.
Winter is mild, with December and January lows near 43°F. January's 84 percent outdoor reading falls away in a heated room. An unheated garage keeps that damp, so the dehumidifier stays on there, with a seedling mat for young roots.
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 59 | 62 | 64 | 67 | 69 | 74 | 75 | 76 | 77 | 74 | 65 | 59 |
| Avg low °F | 43 | 45 | 47 | 50 | 52 | 55 | 57 | 58 | 58 | 54 | 47 | 43 |
| Humidity % | 84 | 72 | 71 | 78 | 76 | 61 |
Highs and lows: NOAA 1991 to 2020 normals, Hayward Air Terminal station (1.9 miles away). Humidity: Open-Meteo historical model data, average daily humidity in 2024, for the months shown. Planning averages, not a forecast.
Outdoors in unincorporated San Lorenzo
California allows 6 living plants per private residence, whatever the count of adults inside, kept behind a lock and out of view of anyone in a public place. Local governments can make reasonable rules for indoor grows, short of a ban, and may ban outdoor grows. San Lorenzo is unincorporated, with no city code of its own, so look up the county rules that cover your address before planting.
Where outdoor plants are allowed, start seeds indoors March 4 to 18 and plant out from April 15. Sow autoflowers, which bloom on age rather than day length, about a week before. Nights average 50°F or warmer from April 21 to November 2, and frost rarely ends the season. The damp does the limiting: a photoperiod plant, which flowers as nights lengthen, fills its buds through August and September. Give it open spacing, a variety known to resist mold, and a daily look at the thickest buds.
| Frost | Rare: about 1.1 freezing nights a year |
|---|---|
| Nights stay 50°F or warmer | Apr 21 to Nov 2 |
| Start seeds or clones indoors | Mar 4 to Mar 18 |
| Move plants outdoors | Apr 15 or later |
Keeping a San Lorenzo grow log private
San Lorenzo is compact, with homes close together and Hayward on one side and San Leandro on the other. A neighbor can hear a dehumidifier that runs all of August, and encryption will not quiet it. What it does protect is the record of how you tuned that room.
Canna GLAP encrypts each grow entry before your phone uploads it, and only your passphrase, which we never see, unlocks it. A person who broke into our servers would find the grow records in coded form, with no way to open them. Your August settings stay a private advantage.
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 Lorenzo ask
Do I need air conditioning for a grow tent in San Lorenzo?
Rarely for heat. For moisture it is the wrong tool: on mild days it barely runs, so a dehumidifier on a humidistat does that job.
Who sets the local grow rules in San Lorenzo?
Because San Lorenzo is unincorporated, it has no city government; county rules apply on top of state law. Check them for both indoor and outdoor grows before you start.
Does San Lorenzo get frost?
Hardly. The Hayward station averages about 1 freezing night a year, and nights average 45°F or warmer from February 14 to December 1.
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