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  • Professor Sprout

Pre-Season Checklist for Growing Early & Fast Flowering Outdoor Cannabis Strains

Updated: Mar 8

For us northern gardeners coming out of winter hibernation, popping seeds in preparation for this season’s outdoor grow is an exciting way to shake off the winter doldrums and look forward to the optimism of summer and a bountiful harvest.  Lately, I’ve been getting a lot of emails from folks asking when they should start their seeds, and if there is anything they should know before starting their outdoor grow.  So, I figured I should put together a list of special consideration you'll need to be mindful of when getting your outdoor crops started this spring.

1) Start with Fast Flowering or Early Flowering Genetics Bred for Outdoor Growing - Avoid “Autos” and “Tent Queens”

If you live on or near the 49th Parallel, you can’t simply plant any ol’ cannabis seed and expect to pull off a successful outdoor harvest without serious skill and a great deal of luck. The majority of today’s popular strains are bred to be grown in climate controlled grow tents with artificial lighting and low risk of pathogens and pests.  Planting these strains outdoors will be fraught with difficulties such as: harvest windows that are too late into the season causing loss of plants to frost and snow, high disease pressure such as botrytis and powdery mildew that wreak havoc on susceptible plants, and inclement weather such as windstorms and heavy rainfall that can damage or even destroy less resilient cultivars.

In the past, day-neutral or “Autoflowering” genetics have been the best solution to the short northern growing season due to their remarkably short life cycle.  However, Autos suffer from some significant drawbacks themselves, such as low yielding ‘dwarf’ plants, lack of potency, and a narrow margin of error thanks to their limited life cycle.  Somewhere along the way Autos garnered the reputation of being a ‘beginners plant’, but nothing could be further form the truth.  The fact of the matter is that Autos do not fare well outdoors in all but the most hospitable of growing environments.  All it takes is a week or two of bad weather; be it too hot or too cold, and you will never be able to achieve the the big yields and beautiful buds you are hoping for.  For these reasons, it is best to avoid growing Autos outdoors unless you absolutely have to.

As a solution to this, Lucky 13 Seed Company offers a number of non-auto, early flowering strains that have been bred especially for short season and northern growers. These cultivars begin flowering much sooner than their standard counterparts, and harvest earlier, well before the risk nasty weather. Their prime flower development period aligns perfectly with the best of the season, and they are bred with greater resistance to pathogens and pests. They also grow much larger with bigger yields than Autos, with a significantly more forgiving growth cycle. See our blog post top-7-outdoor-strains-for-northern-growers-updated-for-2024 if you would like more info on these lines.

2) Grow From Seed, Not Clone

Fast flowering genetics carry a recessive trait that allows them to begin flowering earlier than standard varieties.  However, due to this recessive trait, cloning such varieties is a waste of time.  Clones of fast flowering outdoor strains have a notorious habit of spontaneously flowering when being kept indoors for too long, making it next to impossible to keep mother plants long term.  As such, plan to grow fast flowering strains directly from seed, each season.

3) Don’t Start Too Early.

I know you’re anxious to get planting as soon as possible, but don’t get ahead of yourself.  Germinating fast flowering cannabis seeds too early results in the need to maintain plants indoors until the weather outside is comfortable enough to meet the environmental requirements of a cannabis plant.  This can result in root-bound seedlings or stress-induced premature flowering.  

Additionally, if early flowering cannabis seedlings are kept indoors for too long they become acclimated to a sheltered life.  When it comes time to move the seedlings outdoors, the change in environment can be a significant shock.  This can result in all sorts of problems down the road such as stress-intersex problems, premature flowering, and even plant death.  For these reasons, I typically recommend germinating your fast flowering cannabis strains indoors around April 15 for most northern growers.

4) Match Light Cycles

This step is absolutely crucial when growing early flowering Cannabis strains such as Frostberry or Romulan Warp Drive.  When starting your seedlings indoors, you must set your light timer to the precise sunrise and sunset time of your target outdoor planting date.  After the spring equinox, the day length increases slightly each day until the summer solstice.  If you start your seedlings indoors in April under the standard 18 hours on 6 hours off, and then move them outdoors around the middle of May when the days are less than 16 hours long, your plants may mistake this decrease in daylight as the onset of autumn and begin to flower.  Then as the day length naturally increases approaching the summer solstice, they can revert back to vegetative growth.  This flip-flopping between vegetative growth and flowering may cause mutated growth, premature flowering, intersex issues, and so on.

In order to avoid this potential pitfall, plug your geographical location into an app that tells you the sunrise and sunset times based on your location for your anticipated outdoor planting date.  Next, set your light timer to turn your grow light on and off at precisely those times.  This way, when you move your plants outdoors, they will be on the same light cycle as they were indoors and they won’t miss a beat.

Here at our location at 49 degrees north, our target outdoor planting date is typically May 20th.  We germinate our seeds one month prior to that date, around April 15th, with the grow lights set to come on at 5am and turn off at 8:47pm; the exact sunrise and sunset times for our expected outdoor planting date of May 20th.

5) Grow Big Roots

Having a healthy and thriving root mass is important when transitioning your seedlings to outdoors in the spring.  The typically cool and damp conditions of spring will slow nutrient uptake and make it difficult for your plant to produce the energy it needs to thrive.  An underdeveloped root mass will only make nutrient uptake all the more challenging when hardening off your plants.  A seedling with weak roots can stop growing altogether when moved outdoors.  Some will even perish due to the fact that their roots are insufficient to supply enough nutrients to keep the plant alive.

Applications of kelp and alfalfa extract (both laden with natural plant growth hormones) or a compost tea made of the same; along with inoculating the rhizosphere with mychorrizae fungi can give your roots a massive head start on development and make the indoor to outdoor transition much smoother and safer.

6) Use Blue Light to Germinate

If possible, use T5 fluorescent lighting to germinate your seeds and keep them healthy during the early seedling stage.  T5 fluorescent lights lean heavily into the blue spectrum which will keep your seedlings short with tight internode spacing; avoiding the stretched-out and floppy seedlings commonly found in low light conditions.  T5 lighting also generates little heat, which makes the transition to the cooler spring air much less of a shock.  This low heat output also allows you to keep the seedlings very close to the bulb without risk of burning or bleaching the foliage.  Ceramic Metal Halide lighting is also an excellent choice for early seedling growth due to its spectrum being much closer to natural sunlight than any other artificial source.  When seedlings are started under CMH lighting, the transition to full sun is much less stressful and the hardening off process take significantly less time.

7) Mini Greenhouse

If you plan to grow outdoor cannabis as a regular hobby, it might be a wise idea to invest in a mini greenhouse for your back porch or yard.  These can be found pretty affordably these days, and are the best way to germinate your seeds and get them off to a healthy start without worrying about light cycles, sunrise and sunset matching, and environmental stress. Your seedlings will grow much quicker under natural sunlight, and they will adapt rapidly to the transition to open air growing when the time comes to move them outside of the greenhouse permanently. 

If you really want to step up your game with you can equip your greenhouse with a thermostatically controlled fan that exhausts hot air when the interior temperature rises above a certain set point.  You can also add some low cost LED grow lights as supplemental lighting for those cloudy and overcast days.  Going the extra mile here will allow you to get a major jumpstart on the outdoor growing season that will result in much bigger and stronger plants that will pay you back dividends come harvest time.

-Professor Sprout

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