CannaGLAP
Grow cannabis in South Pasadena, CA
Growing cannabis in South Pasadena: the summer cooling that quietly dries your tent
South Pasadena summers turn a grow room into a cooling project. August afternoons average 91°F, and from July through September about 51 afternoons reach 90°F or hotter.
An air conditioner can handle that heat, and it pulls water out of the room every hour it runs. On a mild night it barely runs, and the drying stops. So is your tent holding steady air, or riding the compressor's schedule?
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.
Heat, cooling and the humidity in between
The heat itself comes first. The Pasadena station, 2.2 miles away at 864 feet, counts about 74 afternoons that hot in a year, and August is the hottest month by day and night together. A tent in a closed garage or an upstairs room can run well above the space around it. Running the lamp from late evening to morning, July through September, moves its heat into nights that average 62 to 63°F.
Treat the air conditioner as a helper for humidity, not the plan. It dries the room only while the compressor runs, so a long August afternoon can leave seedlings and fresh clones in parched air. A mild night, on the other hand, can leave a flowering tent damper than you expect. A small humidifier for young plants and a dehumidifier on a humidistat (a switch that holds the humidity you set) keep the air even either way.
The outside air is moderate. In 2024 it averaged 68 percent humidity in June, 57 in August and 50 in October, the lowest of the months shown, January's 64 included. Those are outdoor readings, so they fit a garage or a room with open windows; a closed, air-conditioned room can sit well below them. For buds ripening in fall, heat is usually a bigger worry than mold.
Winter asks little of a San Gabriel Valley grow. Freezing nights come less than once a year on average, and the average night drops under 45°F only for about two weeks in the second half of December. Those cool nights still chill a garage tent once the lamp switches off, so in December and January keep the lights running through the small hours, when the room is coldest.
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 68 | 69 | 73 | 76 | 78 | 84 | 89 | 91 | 90 | 83 | 75 | 67 |
| Avg low °F | 46 | 46 | 48 | 51 | 54 | 58 | 62 | 63 | 62 | 56 | 50 | 45 |
| Humidity % | 64 | 68 | 61 | 57 | 60 | 50 |
Highs and lows: NOAA 1991 to 2020 normals, Pasadena station (2.2 miles away). Humidity: Open-Meteo historical model data, average daily humidity in 2024, for the months shown. Planning averages, not a forecast.
Outdoors in South Pasadena
California allows 6 living plants per private residence, however many adults share it, in a locked space kept out of view of any public place. Cities and counties can set reasonable rules for indoor grows and may ban outdoor ones, so read whatever local rules apply where you live before you plant anything.
Should your address permit outdoor plants, start seeds March 4 to March 18 and set plants out from April 15, about a week after the average night reaches 50°F. Frost is unlikely to end this season; heat shapes it. Photoperiod plants (they flower as the nights lengthen) ripen in September and October, when the station still averages about 16 and 8 of those hot days. Afternoon shade and watering at dawn help buds through those spells.
| Frost | Rare: less than 1 freezing night a year on average |
|---|---|
| Nights stay 50°F or warmer | Apr 7 to Nov 14 |
| Start seeds or clones indoors | Mar 4 to Mar 18 |
| Move plants outdoors | Apr 15 or later |
Keeping a South Pasadena grow to yourself
In South Pasadena, the Thursday farmers market on Mission Street puts neighbors face to face every week. If your grow is something you would rather not discuss over the produce stands, your journal should be just as discreet.
Canna GLAP scrambles your grow records on your phone, and only that scrambled copy goes up to our servers. Anyone who broke in there would walk away with unreadable files and nothing to open them. That covers the journal, not the smell of a flowering plant through a shared wall, so the tent's carbon filter still matters.
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 South Pasadena ask
Do I need air conditioning to grow cannabis in South Pasadena?
For a summer grow in a closed room, it helps a great deal: about 19 August afternoons reach 90°F. Pair it with a dehumidifier on a humidistat, because the air conditioner only dries the air while it is running.
Does South Pasadena get frost?
Hardly ever. The nearby Pasadena station averages less than one freezing night a year, so winter care is about cool nights in the mid 40s, not frost.
When can I plant cannabis outside in South Pasadena?
From April 15, if local rules allow outdoor plants, after starting photoperiod seeds indoors in the first half of March. Autoflowers keep their own timetable, so sow them only a few days before they go out.
Growing near South Pasadena
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