Why Autoflowering Cannabis is Advantageous in Wet and Humid Climates

By Joe Ullman
Published: June 9, 2022 | Last updated: June 9, 2022 07:26:06
Key Takeaways

How growers across the continental United States can use autoflower seeds strategically to avoid mold growth.

Outdoor cannabis and hemp growers throughout the continental United States face seasonal threats of excessive rain and humidity. Too much rain and humidity can lead to significant crop loss from mold and mildew pressure.


Given that the ideal environment to grow cannabis can often be hot and humid, mold can easily grow if growers aren’t careful and proactive. Mold, commonly referred to as botrytis amongst cultivators, can decimate yields and create a dangerous end product for consumers. Particularly, the toxic chemicals in mold, called mycotoxins, are a health hazard when inhaled, especially by immunocompromised people. Ingesting mycotoxins can even be fatal. Needless to say, mold doesn’t belong in quality cannabis crops and should be avoided at all costs, especially for the finished flower market.

Despite how easily mold can grow, there are practical solutions for combating mold growth and other regional climate challenges that lead to it. For one, timing planting and harvest are important. That way, growers can avoid the more humid months and instead, take advantage of growing during the dry months. Based on your location within the U.S., this timing can and will vary.


This is where autoflowering cannabis comes in. Autoflowering cannabis harvests in half the time—between 60 and 100 days depending on if you’re planting in the summer or shoulder seasons—compared to typical, photoperiod cannabis seeds. The average time it takes to grow and harvest photoperiod cannabis varies greatly depending on the strain, and its longer flowering time means your plants will be exposed to months more moisture and sporadic, inclement weather.

Upper Midwest

In Michigan, growers battle mold from early fall rains ranging from the middle of September through the end of October. Likewise, in Illinois, the climate is similar with temperatures dropping in the late fall season. Although snow isn’t expected until November, northern Illinois certainly gets much chillier sooner compared to southern regions of the upper Midwest in particular.

Growers in the upper Midwest can take advantage of the opportunity to buy autoflowering feminized seeds online. By sowing autoflower seeds early and often in the late spring and early summer, they’ll ensure quality crops in July, August, and early September harvests.

Meanwhile, to contrast, seasoned cultivators in the lower Midwest, such as in Oklahoma, generally wait until the latter half of June to sow their outdoor autoflower crops to avoid the very unpredictable cold, wet, and windy weather often seen in May and early June.


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Growers in the southwestern region, such as in the states of Arizona and New Mexico, experience monsoon rains and increased humidity beginning in the middle of June that last through the end of September.


Although 2020’s monsoon season was the driest since 1956, last year’s was much more wet, particularly in Arizona and New Mexico.

Given how much warmer the spring months are, soil temperatures in this region can be beneficial to growers in March and early April. That way, in the springtime, southwestern growers can sow a crop and ensure a harvest by the time the rain threat arrives as early as June. It’s recommended that growers in the southwest get a head start on their harvest earlier in the year compared to other regions.


The Northeast is home to some of the country’s coldest states and, likewise, can have some of the heaviest snowfalls. It gets chilly fast and snow can follow shortly after. Growers located in Massachusetts, Maine, Vermont, and New York have first frost dates around the beginning of October.

Having the ability to sow and harvest a crop between 70 to 80 days gives ample leeway on planning the best time to plant. The 65- to 80-day maturation period for genetic lines allows for harvests by the middle of September, still beating the photoperiod harvests by about one month. The single best trait for genetic lines is the autoflowering trait. Most every other agronomic food crop has a set amount of time from sowing to harvest.

From carrots to beets to cabbage to lettuce, there is a pre-set amount of time a farmer can expect from sowing to harvest their crop. It wasn’t until recently that cannabis could follow the same agricultural pattern.

Why wait for photoperiod genetic lines to finish flowering outdoors? When the weather takes a seasonally predictable turn for the worse, isn’t it nice to have an effective tool in your farmer toolbelt to successfully combat the weather threat? Autoflower seeds are an effective, practical solution to the many woes cannabis and hemp growers face in challenging climates across the country.


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Written by Joe Ullman | Co-Owner

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Joe Ullman is co-owner of Atlas Seed.

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