sun grown weed

The Future of Cannabis is Sungrown

Sungrown Future

The future of cannabis cultivation is bright. The long-awaited legalization of cultivating this contentious genus represents a new era of commercial Cannabis cultivation, marking the advent of one of the most significant social shifts of our generation. The gravity of specialized teams being able to legally grow Cannabis in quality-controlled environments; while extracting data, honing operations, and analyzing new cultivation strategies at the forefront of agricultural science, has not yet set in for the average Cannabis user. This plant, and it’s place in society, are on a path of radical change over the next 10 years.

Cannabis production has traditionally been undertaken largely indoors in North America. As much as 3% of the State of California’s energy usage, for instance, is attributed to indoor Cannabis production. Understandably, it is far easier to keep black market production covert in a bunker than in a glass box. The problem with indoor cultivation at a commercial scale, however, lies in two core deficiencies:

  1. The conditions of indoor operations are less than ideal for cultivating plants.
  2. The cost of indoor production is not environmentally nor economically sustainable.

At Tantalus Labs, we fight for the idea that modern Greenhouse technology is the future. We believe that Greenhouses will push commercial indoor Cannabis cultivation into obsolescence; ultimately forcing indoor and black market production into technology-driven, legitimate, Sungrown systems.

What Do Plants Need to Grow?

Plants need light, water, and nutrients. Evolving the way nature delivers these three inputs is what 10,000 years of agriculture boil down to. The ability to manipulate an environment to achieve higher productivities or more robust plant health is both a science and an art. The process of designing, testing, revising, and analyzing systems tailored to particular plants has spawned countless branches of science and engineering.

Modern greenhouse technology enables systems that hone the cultivation environment in an optimal way. For critical factors such as light penetration, humidity minimization, and environmental monitoring, there is simply no better system than a high-tech Greenhouse. We grow and evolve as a species by adapting our environment to meet the needs of our agriculture, and the plants that we nurture grow and evolve as well within the systems that we innovate.

Cannabis, for the first time in modern history, is on the cusp of a dramatic agricultural shift. We have a new opportunity to study it with the added benefit of formalized scientific research and understanding. While this is just a piece of the puzzle in terms of its normalization in our society, the most dramatic evolution will manifest in the plant itself.

What are the Advantages of a Greenhouse?

The core advantage of Greenhouse cultivation is that there is simply no better lighting environment in which to grow plants than Sunlight . Cannabis is a plant with a highly efficient photosynthetic process. It will consume as much light as is available, and convert that light into growth at 60X the speed of a Douglas Fir.

* Based on an estimate of optimal spacing of HID lamps in an environment with no natural light (i.e. warehouse etc.) Light Integral data from Fisher, P and Runkle E (eds) 2004

Humidity Minimization

Humidity is the primary enemy of the Cannabis grower looking to avoid mould and disease. Mould is a common adulterant in black market and commercial Cannabis alike, and the more humid the environment, the greater the mould risk. The way that we at Tantalus Labs accomplish humidity minimization is largely through facility design. A central galley way divides the greenhouse facility in two. The galley way functions as a space for work and logistics, but it also serves as a substantial air intake for supplying each bay of the greenhouses on either side.

Air cooled by specialized pads is pulled through the length of the greenhouse via (6) 18in HAF fans. These fans move an ocean of air, beginning above the plant canopy and eventually through it on the back end toward the rear of the greenhouse. Here is located another set of electronic dampers and two 48in exhaust fans mounted just above crop height. Each are rated at

27,000 Cubic Feet per Minute (CFM) for a total of

54,000 CFM per bay. This exhaust air is then dumped into an odor filtration bay, scrubbed, and exhausted into the atmosphere.

Heating, Ventilation, and Air Conditioning (HVAC) only systems function differently, and CFM is much lower. In a top of the line HVAC environment, the range of 15-1800 CFM would be likely. Compare this to Tantalus’ 54,000 CFM. HVAC necessitates a system of supply and return air ducts to feed Air Conditioning units and fans, moving the cooled air around.

Environmental Control

Modern Greenhouses enable the tightest degree of environmental control in agriculture. Systems monitor and record data on a range of granular environmental parameters, from temperature and humidity all the way to soil pH and CO2 levels. These sensors signal mechanical changes when parameters fall outside of optimal ranges. For instance, if the Greenhouse gets too hot, the system will automatically vent through cooling pads, keeping the cultivation environment at the ideal temperature to allow plants to thrive.

Data Gathering

The same sensors that trigger environmental adjustments in Greenhouse record data. This data helps growers better understand the relationships between the environment and trends in productivity, plant health, and potency. Tantalus Labs uses this data in predictive models, helping us refine our practices and learn more about what our plants need to thrive.

Tantalus Labs exists to advance the frontier of cannabis. We designed and built the first facility of its kind on Earth – a completely environmentally controlled greenhouse, engineered specifically for cannabis. We call it SunLab¹.

How Much Sunlight Do Outdoor Cannabis Plants Need To Grow?

Cannabis is a sun-loving plant. But just how much sunlight do weed plants need in order to grow and flower properly?

Find out how much sun your cannabis plant needs, and how to best take advantage of it.


The more sunlight, the better; that’s the golden rule for growing weed outdoors. Unfortunately, we don’t all have access to a terrace, balcony, patio, or garden that receives full sun all throughout the day. In this article, we’ll take a closer look at weed’s passionate relationship with the sun, and show you just how much sunlight your outdoor plants need to produce a great harvest.

Why Does Cannabis Need Sunlight?

Through the power of photosynthesis, cannabis plants transform light energy from the sun into chemical energy to fuel their growth. Your weed plants use the energy they soak up from the sun to convert the water, carbon dioxide, and minerals they get from their environment into oxygen and energy-rich sugars to develop healthy roots, branches, and foliage.

What’s the Difference Between Sunlight and Artificial Light From Grow Lamps?

Whether sunlight “beats” artificial grow lights is an age-old debate in the cannabis community, with proud, loyal legions on either side. At RQS, we’re firm believers that there’s no replacement for Mother Nature, but we understand that growing indoors under artificial lights also has a lot of benefits.

We personally love growing under the sun because it’s free and there’s simply no industrial lamp capable of replicating the sun’s power. However, providing cannabis plants with 10–12 hours of unobstructed sunlight can be challenging for the average home grower, especially when you’re trying to keep your plants out of sight from prying eyes.

That’s where indoor growing really shines; not only does it allow you to run really private grows, but growing under lights also has the added benefit of giving you a lot more control over your plant’s environment and light cycle.

How Much Sunlight Do Outdoor Cannabis Plants Need?

Cannabis plants are happiest when they get between 10–12 hours of direct sunlight per day. As you’ll likely have witnessed with your own eyes, weed plants grow really vigorously, and hence need a ton of solar energy to fuel their growth.

However, it is possible to grow healthy cannabis plants outdoors with a minimum of 6 hours of uninterrupted sunlight. Just keep in mind that these plants will grow slower and therefore may produce lighter and lower-quality yields than plants getting optimal amounts of sun.

Can You Grow Cannabis With Indirect Sunlight Outdoors?

Read through a few grow forums and you’ll find plenty of growers who swear they’ve made it to harvest with just 1 or 2 hours of direct sunlight per day. Cannabis is, after all, a hardy plant that can withstand some pretty rough conditions when growing in the wild.

However, when growing weed at home, you’ll want to provide optimal conditions to maximise the size and quality of your yields. If they’re growing in the shade, your plants will reach for the sun and develop long, lanky branches, few bud sites, and light, airy buds with less resin.

When Do Cannabis Plants Flower Outdoors?

Outdoors, photoperiod cannabis plants will flower after the summer solstice, when the days grow shorter and the nights grow longer. In the Northern Hemisphere, this happens gradually after the June solstice, which usually occurs on June 20th or 21st, depending on the year. In the Southern Hemisphere, cannabis plants will gradually start flowering after the December solstice, which takes place on December 20th or 21st.

Keep in mind that outdoor plants will start flowering gradually, as the daytime hours will diminish much more gradually than indoors, where you will flip your plants from veg to bloom with the flick of a switch.

Is There a Difference Between Sunlight in the Equator vs in the Hemispheres?

Yes, there is a very big difference between sunlight in the hemispheres and the equator (or intertropical zones between the Tropics of Cancer and Capricorn).

Given the Earth’s orbit, its poles tilt toward the sun during different times of the year; the Northern Hemisphere is closest to the sun on the June solstice, while the Southern Hemisphere is closest to the sun during the December solstice. The closer a pole is to the sun, the more direct sunlight it receives, and the longer the days in the corresponding hemisphere.

The equator, however, continually remains at the same distance from the sun. Hence, it gets a constant 12 hours of sunlight all year round.

When to Grow and Harvest Cannabis in the Northern and Southern Hemispheres

Outdoor growers in the Northern Hemisphere will typically germinate their seeds in between spring and early summer, depending on their location. Along the Iberian Peninsula, for example, growers might start in early March and manage to grow two full crops of autos by August. Further north, however, growers will have to start a little later to avoid facing frosts, rain, hail, or other unfavourable conditions.

Growers in the Southern Hemisphere, on the other hand, might kick off their grows as early as September, and will typically harvest between March or May, although some sativas might be ready by early June (depending on the genetics and the local climate).

When growing outdoors, it’s important to know what genetics you’re working with and how they’ll respond to being planted during different times of the season. If you’re growing big sativas, for example, you may want to start your grow a little later to avoid the plants getting too large. If you’re working with fast autos, on the other hand, try to get your seeds in the ground as early as possible to squeeze two harvests into one growing season.

How to Grow Weed Outdoors Along the Equator and in the Tropics

As mentioned earlier, areas along the equator receive a steady 12 hours of sunlight throughout the year. If you’re lucky enough to live in an area sitting on the equator, you might be able to grow cannabis outdoors all year round (weather permitting, of course). In these areas, photoperiod strains might behave similarly to autoflowers, flowering automatically once they reach maturity.

The Tropics of Capricorn and Cancer, on the other hand, receive up to 10.5 and 13.5 hours of sunlight per day following the summer and winter solstices (respectively). In these areas, you might also be able to grow cannabis all year round, depending on the weather, and might find your photoperiod strains to flower based on age rather than a change in light cycle.

Understanding Tropical Cannabis Strains

While cannabis may have its roots in Asia, the plant has managed to spread and adapt (thanks to the help of humans) to almost every corner of the globe. Varieties that have adapted to the unique climate and light cycle of the tropics and equator typically germinate much earlier than those adapted to grow further north or south. They may also stay in veg much longer, and even continue developing foliage as they flower, leading them to produce elongated and airy buds.

Just remember that, although equatorial photoperiod strains might behave similarly to autoflowers, they aren’t true autos. Autoflowering strains contain specific genes from Cannabis ruderalis that cause them to flower based on hormonal changes triggered by age. Photoperiod equatorial strains don’t have this gene, and thus their flowering might still be triggered by light changes (as minimal as they might be along the equator or in the tropics).

Wondering how much direct sunlight cannabis needs to grow properly outdoors? Unsure when to harvest in your hemisphere? Find out the answers inside.