CannaGLAP
Grow cannabis in Lafayette, CO
Growing cannabis in Lafayette: hot July afternoons and only 14 weeks of warm nights
The Northglenn station, 7.7 miles away and 5,407 feet up, averages 91°F in the July afternoon and about 19 days that month at 90 or hotter. Then look at the nights. They average 50°F or warmer only from about June 4 to September 11, roughly 99 days.
Plants feel the night as much as the day, and in a Front Range July the two sit about 32 degrees apart. So when you plan a run, which one are you planning for?
Adults 21 and over: yes (residents). Plant limit: 6 per resident, 3 or fewer flowering; 12 per residential property unless local law allows more.
Enclosed, locked area not openly visible; separate locked space if anyone under 21 lives there; local rules can be stricter. Source: Colorado home grow laws; 12 plant cap: HB 17-1220. Local rules (landlords, HOAs, city codes) can add more; this is a summary, not legal advice.
Inside a Lafayette grow: bridge the day and the night
July and August afternoons average 89°F to 91°F, and a tent in an upstairs room or a garage near Old Town can climb well past that with the lamps on. Run the lights from late evening into the morning, so the lamps add their heat while the outside air is coolest, near 57°F to 59°F in those months, and the tent sits dark through the afternoon.
The air runs dry. July and September each averaged 38 percent humidity and October 40, with August the dampest of the summer months measured at 46. Seedlings and fresh cuttings lose water quickly in that, so a dome and a small humidifier help through the first weeks of veg. The same dry fall air keeps bud rot pressure low, and it dries a harvest fast: hang it in a closed room and let it take its time.
Winter is long and cold. The station logs about 149 freezing nights a year, and December and January lows both average about 19°F. A basement or a room against an outside wall chills hard once the lamps switch off, so warm the root zone and run the lights through the coldest hours. January's 63 percent outdoor humidity changes little inside a heated home, which runs dry all winter.
Plan the plant count before the lights. Colorado limits each resident to 6 plants with 3 or fewer flowering, so one way to run a Lafayette tent is three in veg and three in flower, swapping as each harvest comes down.
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 48 | 50 | 58 | 64 | 72 | 85 | 91 | 89 | 82 | 67 | 56 | 48 |
| Avg low °F | 19 | 20 | 28 | 35 | 44 | 53 | 59 | 57 | 49 | 37 | 27 | 19 |
| Humidity % | 63 | 43 | 38 | 46 | 38 | 40 |
Highs and lows: NOAA 1991 to 2020 normals, Northglenn station (7.7 miles away). Humidity: Open-Meteo historical model data, average daily humidity in 2024, for the months shown. Planning averages, not a forecast.
The Lafayette outdoor season: about 131 days
Colorado allows home growing for residents only, and the plants must be in an enclosed, locked area that is not openly visible, with a separate locked space if anyone under 21 lives in the home. The property limit is 12 plants unless local law allows more, and local rules can be stricter. If your space meets all of that, start seeds April 6 to 20 and set plants out May 18, when nights first average 45°F. The last frost usually comes around May 2, and one spring in ten as late as May 14.
The end comes early. Nights average below 45°F after September 25, and the early first frost can arrive September 26, about 131 days after transplant. A plant that flowers through those cool September nights near 49°F needs to be finished by the last week of the month, which points to autoflowers and fast photoperiods.
| Last spring frost | May 2 in a typical year, May 14 to be safe (later only 1 year in 10) |
|---|---|
| First fall frost | Oct 11 typical, as early as Sep 26 (1 year in 10) |
| Frost-free season | about 160 days |
| Nights stay 50°F or warmer | Jun 4 to Sep 11 |
| Start seeds or clones indoors | Apr 6 to Apr 20 |
| Move plants outdoors | May 18 or later |
| Season note | Frost can arrive before mid October here: long flowering plants may not finish outdoors |
Your Old Town grow log, sealed
Lafayette is a town of about 30,000, and Old Town draws people from across the area, so you keep running into the same faces. Some of them grow too, and once harvest season arrives the comparing starts. What your grow taught you this year is yours to share on your own terms.
Canna GLAP locks your grow records with encryption on the phone, before upload. If someone broke into our servers, they would come away with grow entries no one can read and no key to open them.
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 Lafayette ask
When can I plant cannabis outside in Lafayette, Colorado?
May 18 or later, from seeds started April 6 to 20. That is when nights first average 45°F, a few days after the late frost date of May 14.
How many cannabis plants can I grow in Lafayette?
Colorado allows 6 per resident with 3 or fewer flowering, and 12 per residential property unless local law allows more. Local rules can be stricter.
Do I need a dehumidifier for flowering in Lafayette?
Seldom. September and October averaged about 39 percent humidity, low enough that bud rot finds little to work with.
Growing near Lafayette
- Grow cannabis in Broomfield, CO 5 miles
- Grow cannabis in Northglenn, CO 9 miles
- Grow cannabis in Boulder, CO 10 miles
- Grow cannabis in Thornton, CO 11 miles
- Grow cannabis in Westminster, CO 11 miles
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