CannaGLAP
Grow cannabis in Gresham, OR
Growing cannabis in Gresham: more season than your plant can safely use
On paper, Gresham hands a grower a generous year. The Troutdale airport station, about 4 miles away, counts only about 28 freezing nights a year, and the first frost of fall usually waits until November 20. Plants can go out on April 25 and stay out for months.
The question is not whether the season is long enough. It is how much of it is dry. July averages 59 percent humidity, then the air climbs to 72 percent in September and 79 in October. How far into that wet stretch is your plant still flowering?
Adults 21 and over: yes. Plant limit: 4 per household, however many adults live there.
Four adults in one home still means 4 plants in total. Source: OLCC FAQ. Local rules (landlords, HOAs, city codes) can add more; this is a summary, not legal advice.
Indoors in Gresham: the damp never fully leaves
Indoors, the challenge is water in the air for most of the year, not temperature. January averages 85 percent humidity, the highest of the months measured, while lows sit near 37°F in December and January. A garage or basement tent in Multnomah County stays cool and clammy rather than frozen, the mix that beads condensation on tent walls overnight. Where it does, run a dehumidifier through winter as well as in flower, with a little steady heat from a thermostat heater so the tent stays warmer than the walls around it. A tent in a heated living space usually stays dry enough in winter without one.
Summer is the window to use. July is the driest month measured, at 59 percent, and heat stays modest: about 6 days each in July and August reach 90°F, with nights near 57°F. A tent in a Rockwood apartment or a house near Main City Park can run its lights overnight and draw in that cooler, drier air. An indoor run that flowers through July and August and comes down before September skips the damp fall months.
Once fall arrives, the flower room needs a defense. With outdoor air at 72 percent in September and 79 in October, everything your exhaust pulls in is wet. Keep the dehumidifier ahead of it, aim a fan through the inner canopy, and thin interior branches early in flower so the thickest colas are not pressed together.
Heater safety: use one with tip-over and overheat shutoff, plug it straight into a wall outlet (not an extension cord or power strip), and keep it a few feet from tent fabric and plants.
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 47 | 51 | 57 | 62 | 69 | 74 | 82 | 82 | 76 | 64 | 53 | 46 |
| Avg low °F | 37 | 38 | 40 | 43 | 49 | 53 | 57 | 57 | 52 | 46 | 42 | 37 |
| Humidity % | 85 | 70 | 59 | 65 | 72 | 79 |
Highs and lows: NOAA 1991 to 2020 normals, Portland Troutdale Airport station (3.7 miles away). Humidity: Open-Meteo historical model data, average daily humidity in 2024, for the months shown. Planning averages, not a forecast.
Outdoors in Gresham: use the length for growth, not for flower
Oregon counts plants by household: 4 in total, however many adults share the home, so a house of four adults still has 4 plants between them. Start seeds or clones under lights from March 14 to March 28 and plant out on April 25 or later. Frost usually ends by March 16 and April 12 is the safer date, but average nights only reach 45°F on April 25, and that is what decides the start here.
From there you have about 188 days before even an early first frost on October 30, and nights fall below a 45°F average around October 25. Spend that length on vegetative growth, not on a long flowering period. Choose mold-resistant strains that finish in late September or the first days of October, before October's 79 percent air settles into the buds, and keep a rain cover ready for wet spells.
| Last spring frost | Mar 16 in a typical year, Apr 12 to be safe (later only 1 year in 10) |
|---|---|
| First fall frost | Nov 20 typical, as early as Oct 30 (1 year in 10) |
| Frost-free season | about 250 days |
| Nights stay 50°F or warmer | May 24 to Sep 28 |
| Start seeds or clones indoors | Mar 14 to Mar 28 |
| Move plants outdoors | Apr 25 or later |
Four plants, and notes that stay in the household
With 4 plants per household, a Gresham grow is small enough that every plant matters and every note matters more. Swap stories at the Gresham Farmers Market or the Third Thursday Street Fair. What you write down is worth more than the stories, because four plants give you only so many chances to learn.
Canna GLAP encrypts the grow records on the phone before anything uploads. Should anyone force a way into our servers, what they took from your grow would be unreadable, and the key would not be there.
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 Gresham ask
How early can I plant outdoors in Gresham?
April 25. Start seeds or clones inside March 14 to March 28. Frost is usually gone by mid March, but the average night is under 45°F until April 25.
Is Gresham's long season good for late-flowering strains?
Not really. Frost usually waits until November 20, but October averages 79 percent humidity, so late flowers sit in damp air. Use the long season for bigger plants and harvest by early October.
How many plants can a Gresham household grow?
Four in total under Oregon law, however many adults live in the home. A household of four adults still shares 4 plants.
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