Planning, genetics, pot size, timing and ground transfer key to successful outdoor cannabis

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Siskiyou Sungrown

To decide which genetics to cultivate, Siskiyou Sungrown management evaluates which strains have been performing well in the field and at retail. (Courtesy photo)

Outdoor cannabis cultivators have little to no room for error.

“We get one shot,” said Michael Johnson, chief operating officer of Siskiyou Sungrown in Oregon. “We plant in the late spring and harvest in the fall.

“It’s a little bit more complicated because we don’t have multiple cycles in the year, and you really have to get it right.”

Planning helps growers improve their chances of getting it right.

“To be a true farmer, planning is everything,” Johnson said.

Careful planning includes picking the strains that will grow well in your climate.

Johnson and his Siskiyou teammates spend January and February digging into heavy planning. “You pick the right times for everything. By the end of February, the entire year is planned out,” Johnson said.

The first decision to make is what strains to grow. Johnson taps Siskiyou’s “pretty big genetic library,” which is in-house, and considers which strains have been doing well both in the marketplace and in the field. Then he uses this information to formulate a plan.

“In choosing genetics for outdoor cultivation, it’s imperative that you are confident they are going to grow well in your climate,” Johnson said. “The majority of cannabis genetics in the world would not work well in any given climate—ours included, because there’s just so much nuance.”

For example, many cultivars—sativas in particular—originated in warm, humid climates like those in Central America, the Caribbean and Southeast Asia.

“You really have to make sure that your cultivars are going to be well-acclimated to your environment,” Johnson said, adding that it might take a few harvests to determine whether a certain strain is a good fit for your area.

It’s also critical to look at the photo periods—the length of day and night—that trigger plants to go into flower. “This is No. 1,” Johnson said.

When breeding, pick pollen sources that have proved successful in the past.

Breeding is another important part of the growing season. Siskiyou does the breeding in-house. The cultivation team produces its own feminized seeds using pollen from male plants on female plants that have been “winners in the past.”

“We’ve got a stable of females ready to receive the pollen and create lots of seed. By about March, we are finishing up our big breeding rounds,” Johnson said. This will yield 9,000 to 10,000 seeds.

Siskiyou makes a “big push” in the first two weeks of April, filling 8,000-9,000 individual plastic pots with organic potting soil and setting them up in the greenhouse so the soil gets acclimated to the temperature and other environmental factors.

Workers then place each individual seed into a small pot by hand with tweezers, cover it with soil and give it a little water. Then, in middle to late April, they germinate the seeds.

“That next 30 days, from middle April to the middle of May, is very delicately watching the temperatures and moisture content of those pots,” Johnson said.

Of the 9,000-10,000 original greenhouse seedlings, about 6,000 seedlings make it into the field by late May.

It’s imperative that cultivators have materials ordered and prepped by the time the germination and transplanting phases begin, Johnson said.

Pick the right pot size for your seedlings.

The bigger the pot, the more room the roots have to grow—so that when they are transplanted into the ground they can continue to grow and thrive.

The downside to a larger pot, Johnson said, is that more soil equals more cost and a greater carbon footprint. Soil contains carbon that is released when it is tilled for agriculture. Repeatedly manipulating soil increases atmospheric carbon, which can contribute to climate change.

“We’re doing somewhere in the range of 8,000 to 9,000 seedlings in one push. So even an extra few inches in width or depth of a soil pot can really add up. And we’re very cognizant of our carbon footprint, as much as we are about our input costs,” he said.

It also takes more time and labor to transfer plants into the earth from big pots than small ones.

“The larger the pot you use, the more time it takes for someone to come in, gently pull the thing out of the pot and dig a little hole and stuff it in the earth,” Johnson said. “We found that in years past, when we used a larger pot, the time for planting just took way too long. We’re at a place now where a crew of three to five people can plant 6,000 plants in less than a work week.”

But while smaller pots are cheaper and require less time to transplant outdoors, the plants’ roots run a higher risk of becoming rootbound—or stop growing because they’re bunched up. When rootbound plants are transplanted, it typically takes a couple of weeks for them to grow again.

If plants are starting to get rootbound in the pot but a late freeze or other harsh weather prevents moving them outside, growers run the risk of their plants getting stunted. The roots will correct after a couple of weeks, but losing two weeks in a vegetative growth cycle of only 12 weeks is significant.

“The way we look at it is, we have a finite amount of time: Outdoors, these plants are going to flower at the same time, regardless of whether you plant them in the middle of May or at the Fourth of July. They are going to flower at the same time because they flower based on the environmental conditions and the photo period that’s telling that plant to go into flower,” Johnson said.

Decide when to move your plants from the greenhouse outdoors.

Choosing a planting date—when the plants are taken from the greenhouse and replanted outdoors—should be an early part of your planning process.

“In a perfect world, you would plant as early as you can,” Johnson noted. But the decision about when to plant is really made by Mother Nature and the last days when freezing temperatures can damage plants.

It’s also important to factor in a buffer between the last expected frost date and when you actually start planting. Johnson usually goes with seven to 10 days.

In Siskiyou’s case, that’s around May 15-20, said. “We plan around the last frost, and the thought process is, ‘How do we plant at that moment and give our plants the best chance of success?’”

Many factors go into the answer, Johnson said, including:

  • What is the ideal age and height of a seedling when you put it in the field?
  • What is the size of the pot the plant is in?
  • How much soil is in the pot?
  • How wide and deep is the pot?
  • How big of a taproot have you cultivated?

Use cultivars that flower and finish over a period suitable for your needs.

Another important consideration is how long plants need from the point of flowering to harvest, Johnson said.

“In nature, it’s not that simple,” he said, because the light cycles can’t be adjusted with the flick of a light switch like they can be indoors.

“It’s a gradual transition. Certain cultivars may transition into flower at 14 hours of daylight, and some cultivars may flip into flower at 12 hours of daylight,” Johnson explained. “Neither of those indicate how long it will take from flip for the plant to finish. There are cultivars that flip early and take a long time to finish. And there are cultivars that flip late but take a short time to finish.”

Johnson and other growers said indica-leaning hybrids are better suited to colder, more-rugged northern growing regions because they require only a short period from flowering to finish in such climates. Sativas and sativa hybrids such as Sour Diesel and Amnesia Haze do well in warmer outdoor climates, although growers will want to factor in humidity as well.

In the end, a good planting season boils down to good planning.

“Purchasing all your stuff ahead of time, making sure it’s landed on site, making sure everything is lined up, is critical, because time is of the essence,” Johnson said. “We don’t have any time to waste when the springtime hits.”