How Much Sunlight for Outdoor Marijuana Plants

How Much Sunlight for Outdoor Marijuana Plants
December 03, 2020

We all know that outdoor marijuana plants need sunlight to grow. The question is, how much sunlight do they need so that not only do they survive but also thrive? How much is enough so that they could attain their full potential, giving you insane yields of super potent buds?

Growing cannabis outdoors provides one unique advantage over growing indoors. No artificial light is better than the sun. What nature provides, though, you cannot control. You cannot dictate when the sun will shine, and for how long. Instead, what we – as our forefathers did – was to plant crops following the given climatic conditions of a geographical region. In other words, there is a specific time to germinate seeds, plant seedlings, up until harvesting. Much of this is predetermined by the light requirements of the plants across all stages of growth.

When you start the seeds at the right time, in an ideal location, you do not have to worry much about the sunlight. Mother Nature will do all the work. You just need to keep an eye on the garden, provide water and nutrients while also preventing pests and diseases from becoming a problem.

Sounds easy enough, right?

In this article, we’ll tell you how much sunlight outdoor marijuana plants need, including when and where to grow for maximum potency and yields.

Sunlight Requirements of Outdoor Marijuana Plants

Cannabis plants need light for photosynthesis. In this process, the organelles found inside the leaves – chloroplasts – capture light energy and use it to convert carbon dioxide and water into food. The manufactured food – which comes in the form of glucose – fuels vital processes, including respiration, growth, and reproduction.

Sunlight is considered the ultimate light for marijuana plants. That is because it provides full-spectrum light, covering all the wavelengths that are useful to plants. Of note are two wavelengths that are critical to growth. One is the blue spectrum, which plants need to grow in mass and develop stems, branches, and leaves. Another is the red spectrum, which is critical to developing flowers and trichomes.

The sun, being an able provider, is good news for outdoor marijuana plants, right?

Here’s the thing. Sunlight is not always available. It could be due to the season or the location of your garden. This is why careful planning is of utmost importance. Aside from choosing an optimal spot, timing is also crucial. The last thing you want is for the plants to fall short of their light requirements, or to still be outside as winter looms closer.

Note: This guide focuses on the Northern Hemisphere. Also, you may need to adjust the timeframe depending on the local weather and climate.

How Much Sunlight for Photoperiod Strains

Cannabis plants, with the exemption of autos, are photoperiodic, so this means your standard feminized seeds and regular seeds. Simply put, they are sensitive to light changes. Also, the amount of light they receive in a day – also called the photoperiod – triggers specific biological responses. For instance, the crops need “short days” and “long nights” to switch to the flowering phase.

Vegetative Stage

During the vegetative stage, the primary goal of the cannabis plant is to grow and expand the roots, branches, and leaves. They need as much sunlight as they can get to fuel rapid growth and development.

To be on track, germinate the seeds anytime between the spring equinox and late-April. Some push it to late-May. What should happen is that the plants are already outside when the summer solstice arrives by June 20-22.

Note: Ideally, you should jumpstart the growing process when the days are long, and the temperatures are warm. But in some places, the March weather is still too cold or erratic. If so, consider germinating and raising the plants indoors first. Bring them outside once the weather conditions have more or less stabilized. Remember, they need to be outdoors before summer rolls in.

Flowering Stage

This final growth stage is all about budding and producing resin. During this time, the photoperiod also plays a vital role. That is because cannabis plants require a 12-12 light cycle – or 12 hours of light and 12 hours of darkness – to bloom.

As the days become shorter towards the end of summer (or the start of autumn), the plants naturally receive less sunlight. It also indicates that they are almost at the end of their life cycle. In response, the plants will begin flowering so they can reproduce before winter.

Marijuana outdoors in flower

If you’re right on schedule, the buds should be ready for collection by the autumnal equinox, which occurs at around September 22-23. It is important to harvest before the cold sets in. Otherwise, the buds may become moldy. The assumption, of course, is that most of the trichomes have turned milky or cloudy in color, indicating maximum potency. At this point, around 60% to 70% of the pistils would have also have become darker.

Note: During the dark cycle, avoid light leaks at all costs. Street lamps and motion sensor lights are common culprits. They can confuse marijuana plants and cause them to revert to the vegetative stage. Worse, the plants can get stressed out, become hermaphrodites, and release pollen everywhere. This can spoil an otherwise high-quality harvest. Consider using garbage bags or light-proof tarps to keep the surroundings pitch-black.

How Much Sunlight for Autoflowering Strains

Autoflowering seeds grow into plants that do not rely on light changes to start blooming. Instead, they flower automatically, usually after 2-4 weeks of vegetating. After 6 to 8 more weeks, you can begin harvesting the buds.

Modern autos, in general, prefer longer days or more sunlight exposure. But really, you don’t have to worry too much. Compared to photoperiods, they can endure light interruptions and sparse sunshine much better.

A more pressing concern for autos is when to begin growing. If you start by early spring, for example, you can harvest multiple times in a year. Because of their short life cycle, you could start another batch summer, and then in early autumn.

Choose an Optimal Spot

Selecting the gardening site for your outdoor marijuana plants is, without a doubt, one of the most critical decisions you’ll make as a grower. It can be the difference between explosive yields and a meager harvest.

As a rule of thumb, the chosen spot should receive at least five hours of direct sunlight and five more hours of continuous indirect sun exposure every day. Also, during the height of summer, the sun can shine for over 12 hours a day. You want to take advantage of that.

Optimal outdoor growing spot for cannabis

If possible, opt for areas that face the south, which typically get the sun all day. Make sure there are no obstructions like houses, buildings, or large trees. Also, do not forget to keep the plants out of sight. The last thing you want is for pedestrians to notice the garden.