How to Grow Cannabis Outdoors
This article was co-authored by Jamie Corroon, ND, MPH. Dr. Jamie Corroon, ND, MPH is the founder and Medical Director of the Center for Medical Cannabis Education. Dr. Corroon is a licensed Naturopathic Doctor and clinical researcher. In addition to clinical practice, Dr. Corroon advises dietary supplement and cannabis companies regarding science, regulation, and product development. He is well published in the peer-review literature, with recent publications that investigate the clinical and public health implications of the broadening acceptance of cannabis in society. He earned a Masters in Public Health (MPH) in Epidemiology from San Diego State University. He also earned a Doctor of Naturopathic Medicine degree from Bastyr University, subsequently completed two years of residency at the Bastyr Center for Natural Health, and is a former adjunct professor at Bastyr University California.
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Growing marijuana outdoors produces a higher yield, gives your buds a unique flavor, and it’s far less energy-intensive than using indoor grow lights. Outdoor cannabis plants can grow up to 14 feet (4.3 m) tall and produce 4–8 pounds (1.8–3.6 kg) of quality weed per plant–and it’s not rocket science to grow cannabis outdoors. We’ve put together a comprehensive guide to tell you everything you need to know about picking a location, germinating marijuana seeds, and maintaining your crop to get the highest possible cannabis yield.
How to grow marijuana outdoors
Growing marijuana outdoors is great because you won’t need to spend a ton of money on it and you can rely on the power of the sun. If you have access to a sunny spot in a private yard or even a balcony, terrace, or rooftop, you can grow weed outside. You will be tied to the sun and the seasons and local weather, but you won’t have to spend a bunch of money on equipment and utilities like indoor growers.
If you’re growing weed outdoors, it’s great to find a community of cannabis growers in your area to see how others are growing in your specific climate. Local climates vary, so it can be helpful to see what strains thrive where you are, and also when other growers are popping seeds, harvesting, and more. You can also join online forums or Social media groups, but a great place to start is your local grow shop.
Benefits of growing weed outdoors
Relying on the power of the sun, you won’t need to spend a ton of money on an outdoor grow. You’ll need some soil, fertilizer, seeds or clones, and maybe a small greenhouse to get them started. You won’t need to pay for electricity for lights, AC units, or dehumidifiers, and you can even collect rainwater.
The sky’s the limit with outdoor plants—you can let them get as big and tall as you want, as long as they’re manageable. One plant can potentially yield between a half-pound and full-pound of dried weed! Growing a handful of hands for yourself is more than enough. With an indoor grow, your space is a lot more restricted.
Indoor grows can be wasteful, using a ton of electricity to power all those lights, fans, and other equipment. The sun and the wind are free!
It’s fun and relaxing
Don’t underestimate the therapeutic value of gardening. It’s relaxing to spend some time outside, roll up your sleeves, and get your hands dirty for a while. And there’s nothing better than smoking something you grew yourself.
How to set up your outdoor marijuana grow
Here are some important considerations before starting an outdoor marijuana grow.
Climate in your area
It’s crucial to have a good understanding of the climate in the area you’re going to grow. Cannabis is highly adaptable to various conditions, but it is susceptible in extreme weather.
Sustained temperatures above 85°F will cause your plants to stop growing, while continued temperatures below 55°F can cause damage and stunting to plants, even death.
Heavy rains and high winds can cause physical damage to plants and reduce yields, and excessive moisture can lead to mold and powdery mildew, especially during the flowering stage.
Choosing the best outdoor cannabis grow site
Once you have an understanding of the climate in your area, you’ll need to consider a few things before planting your weed.
Weed plants will need full, direct sun for at least 6 hours a day. You may have a backyard, but it might not be great to grow there if it doesn’t get full sun every day.
Your cannabis plants should receive as much direct sunlight as possible, ideally during midday, when the quality of light is best. As the season changes and fall approaches, your plants will get less and less sunlight throughout the day, which will trigger the flowering stage.
Having a constant breeze is good for your plants, and especially in hot climates. But if you live in an area with a lot of high winds, consider planting near a windbreak of some sort, like a wall, fence or large shrubbery.
Privacy and security
You also want to consider privacy and security. A lot of people want to conceal their gardens from judgmental neighbors and potential thieves. Tall fences and large shrubs or trees are your best bet, unless you live in a secluded area. Also, most state laws require that you keep cannabis plants concealed from the street.
Types of outdoor grow spaces
Some growers plant in containers on balconies or rooftops that are shielded from view, while some build heavy-gauge wire cages to keep thieves and animals at bay. Whatever you decide, think about how big you want your final plant to be—outdoor cannabis plants can grow to 10 feet tall or even more, depending on how much you let them go.
Garden plot: Probably the most common outdoor growing spot, many will plant cannabis alongside other growing veggies.
Balcony: This can be a great spot if it gets good light—ideally, it faces south—and will usually get good wind. However, you may need to cover your balcony from peeping neighbors.
Roof: This can be great for sun but may have too much wind.
Soil and other media for outdoor cannabis growing
Soil, at a basic level, is defined as the topmost layer of earth in which plants grow—it’s a mixture of organic remains, clay, and rock particles. Cannabis plants thrive in soil rich with organic matter, and they need good drainage.
Most outdoor weed growers will either dig a hole and add fresh soil for the plant, or grow their weed in pots. This will allow you to better control the growing medium and the amount of nutrients your plants receive.
You can plant directly into the ground, using the preexisting soil, but you’ll need to understand your soil’s composition and amend it accordingly. If you go this route, we recommend getting your soil tested, which will minimize headaches, and it’s easy and relatively inexpensive. A soil test will tell you the makeup and pH of your soil, any contaminants present, and will recommend materials and fertilizers to amend your soil.
Soil has three basic consistencies, in various ratios:
Soil also varies in:
- pH level
- Water retention
- Nutrient makeup
Silty soil is the ideal growing medium. It’s easy to work, warms quickly, holds moisture, has good drainage, and contains a lot of nutrients. The best silty soil is dark, crumbly loam—it’s fertile and probably won’t need any amending.
- Medium granular size
- Naturally fertile (contains nutrients)
- Retains water
- Stabilizes plants
- Poor drainage
- Easily compacted
Sandy soil is easy to work, drains well, and warms quickly, but it doesn’t hold nutrients well, especially in rainy environments. You’ll want to dig large holes for your plants and add compost, peat moss, or coco coir, which will help bind the soil together.
In hot climates, sandy soil should be mulched to help with water retention and to keep roots from getting too hot.
- Large granular size
- Low pH
- Good drainage
- Prevents compaction
- Easy to work with
- High oxygen levels
- Poor water retention
- Dries out quickly
- Nutrients get washed away
Heavy clay soils drain slowly and don’t hold oxygen well, so they will need to be heavily amended. A few weeks before you plant, dig large holes where you’ll be placing your weed plants and mix in big amounts of compost, manure, worm castings, or other decomposed organic matter. This will provide aeration and drainage, as well as nutrients for the plants.
- Small granular size
- High pH
- Provides minerals
- Retains water
- Stabilizes plants
- Poor drainage
- Heavy soil
- Hard to work
While some plants thrive in their native soils, which are usually one of the compositions listed above, cannabis plants are best grown in soil that includes a combination of the three consistencies above—this mixture is known as loam.
The best way to identify loamy soil is by touching it. How does it feel? Sandy soil should be difficult to compact while clay should compact into a tight ball that won’t crumble. When squeezed, loamy soils should form a loose ball that will hold its structure momentarily before breaking apart in large chunks.
- Mixture of sand, silt, and clay
- Near neutral pH
- Water retention
- Naturally fertile
- Easy to work
- Nutrient retention
- Supports microorganisms
- High oxygen levels
Most potting soils used in gardening are loam soils. If you’ve ever worked with potting soil, you’ll know that its composition is rich and diverse, and it looks dark and hearty. Beyond texture and color, the soil should smell rich and alive.
Buying the right soil for an outdoor cannabis grow
For most first-time gardeners, we recommend buying a quality potting soil that will provide your plants with enough nutrients to get them through most of their growth cycle without having to add many amendments. This pre-fertilized soil—often referred to as “super-soil”—that can grow cannabis plants from start to finish without any added nutrients if used correctly.
You can make this yourself by combining worm castings, bat guano, and other components with a good soil and letting it sit for a few weeks, or it can be purchased pre-made from a local nursery or grow shop.
While shopping for soil, you might be overwhelmed by the options available at your local garden store. The soil type is the basic structure of your soil. From there, look at nutrients, microorganisms, and other amendments that improve the soil. Your choices will be flooded with words like:
- Worm castings
- Bat guano
- Peat moss
- Fish meal
- Bone meal
- Glacier rock dust
- Plant food
These are just some examples of amendments commonly used in different types of soils. Heavily amended soils will have long lists that break down all organic nutrients they contain. Some companies create soils that offer a great structure with base nutrients, but allow you to fill in the gaps as you desire.
You may need to put all of your plants in containers if you don’t have great soil. Also, if you’re unable to perform the heavy labor needed to dig holes and amend soil, containers may be the only way for you to grow your own cannabis outdoors.
If you don’t have a suitable patch of earth to make a garden, containers can be placed on decks, patios, rooftops, and many other spots. If needed, you can move them around during the day to take advantage of the sun or to shield them from excessive heat or wind.
However, plants grown in pots, buckets, or barrels will likely be smaller than those planted in the ground because their root growth is restricted to the size of the container. In a broad sense, the size of the pot will determine the size of the plant, although it’s possible to grow large plants in small containers if proper techniques are used.
What size pot do I need?
In general, 5-gallon pots are a good size for small-to-medium outdoor plants, and 10-gallon pots or larger are recommended for big plants. Regardless of size, you’ll want to protect the roots of your plants from overheating during warm weather, as pots can quickly get hot in direct sunlight. This will severely limit the growth of your plants, so be sure to shade your containers when the sun is high in the sky.
Fertilizers and nutrients for outdoor soil
Cannabis plants require a large amount of nutrients over their life cycle, mainly in the form of nitrogen, phosphorus, and potassium. How much you need to add to your plants will depend on the composition of your soil.
Typically, outdoor growers will add amendments to soil when weed plants are transplanted outside. Outdoor amendments usually come in powder form that you mix in with soil.
Start off with fertilizers that are inexpensive and readily available. Some release nutrients quickly and are easily used by the plant, while others take weeks or months to release usable nutrients. If done correctly, you can mix in a few of these products with your soil amendments to provide enough nutrients for the entire life of your plants. Most of these items can be purchased cheaply at your local nursery.
We recommend these organic fertilizers:
- Blood meal or fish meal for nitrogen
- Bone meal or bat guano for phosphorus
- Wood ash or kelp meal for potassium
- Dolomite lime for calcium and magnesium
- Epsom salts for magnesium and sulfur
There are also commercially available soil blends that already contain the proper mix of these types of ingredients.
For first-time growers, we recommend avoiding commercial fertilizers like long-release granular fertilizers. These can be used, but you need to have a good understanding of how they work and what your plants need.
We also advise against using nutrients designed for indoor weed growing—they are generally composed of synthetic mineral salts and can damage soil bacteria.
Again, getting your soil tested can be very useful and will tell you how to amend your soil and what types and amounts of fertilizer to use. If you are unsure how much to use, be conservative, as you can always add nutrients to the top of soil—called “top dressing”—if plants start to show deficiencies.
How to Grow Marijuana Outdoors
Growing marijuana plants outdoors is generally easier than growing them indoors because Mother Nature chips in to do some of the work. Even so, you have to lay the groundwork for a successful grow to ensure that your plants receive the nutrients they need. Here, we lead you through the process of preparing a site for outdoor cultivation.
As long as you have a sunny location in an area where you get at least eight to ten weeks of relatively sunny weather and temperatures between 60 and 90 degrees Fahrenheit, you can grow cannabis outdoors. If your growing season is short, you can get a jump on things by starting your plants indoors and then transplanting your seedlings (after a brief hardening period). If you live in a warmer climate, you can simply plant your seeds outside after the threat of frost passes.
How to choose a cannabis grow site
- Compliance: Your grow site must comply with all local rules and regulations. It must be private property owned by you. In most locations, your garden must be secure with a privacy fence and plants no taller than the fence. Any gates must be locked to prevent kids from getting to the plants and to discourage theft.
- Space: The amount of space you need depends on the number and types of plants you want to and are legally permitted to grow. Your plants will need to be spaced at least three to five feet apart, so they all get plenty of sun and breeze.
Think ahead. Will each plant have enough space when fully grown? Will plants shade other plants from the sun?
- Soil: Cannabis can grow in a wide variety of soil types, as long as the soil has sufficient drainage. If it doesn’t, you can amend the soil or plant in containers.
- Sunlight and darkness: Cannabis plants need at least five hours of direct sunlight plus at least five hours of indirect sun daily. They’ll reward you for more sun with a bountiful harvest. Also, don’t plant a photoperiod strain under or near a bright street lamp; otherwise, it may not flower properly.
Consider surrounding objects such as buildings and trees and how the angle of the sun changes over the course of the growing season. As a result, an area that gets full sun all day long during one part of the growing season may be shaded part or all of the day during another part of the growing season. Ideally, your grow site will get sun all day long throughout the growing season.
- Convenient access: You’ll be tending to your plants regularly and be eager to watch them grow, so pick a location with easy access. A backyard garden may be ideal.
- Access to water: Unless it rains every few days, you’ll need to water your plants regularly, so pick a site that has easy access to water.
Cannabis must be grown on private property, so you must own the land. Growing on public land, such as a national park or forest, is illegal.
Evaluate the soil
- Loamy: Loam soil is a combination of approximately equal parts of sand and silt along with relatively little clay. It retains moisture, but it also drains well, so plants aren’t sitting in saturated soil in which they’re susceptible to root rot and other diseases. Loam soil crumbles easily in your hands. If the soil is rock hard when dry, it contains too much clay. If it doesn’t hold together at all when you squeeze it into a ball, it may be too sandy.
- Fertile: Healthy soil also contains organic matter, such as decomposing wood and other plant matter. You can mix mulch and other amendments into the soil to increase its fertility, if necessary.
- Slightly acidic: You can use a pH meter to test the soil’s pH, which should be in a range of 5.5 to 6.5. Anything lower is too acidic, and anything higher is too alkaline.
- Alive: Good soil is home to many critters, including earthworms and beneficial bacteria and other microorganisms. If you don’t see anything crawling around in your soil, it’s probably lacking in organic matter.
Take a soup can of soil from several areas around your grow site to your local nursery or university extension office to have your soil tested. Test results show pH levels; levels of key nutrients, including potassium, phosphorous, and nitrogen; concentrations of organic matter; and so on. You may also receive specific recommendations on amendments needed to improve soil quality.
For a more thorough guide to evaluating outdoor soil, check out the free Willamette Valley Soil Quality Card Guide published by Oregon State University.
Decide whether to grow in-ground or in containers
- Planting in-ground is generally easier and more forgiving. With quality soil, you don’t have to worry so much about plants becoming root bound or developing root rot, and you may not have to water as frequently.
- Containers add height which may make your plants taller than allowed by law or taller than the privacy fence you built.
- If containers are too small, plants can get root bound, preventing them from absorbing the water and nutrients they need. In containers, plants may also be more susceptible to root rot if the plants don’t drain properly.
- You can move containers around if the sunny locations in your space change over the course of the growing season.
- If you have poor quality soil, you need to amend the soil prior to planting, which adds to the cost and work involved.
- In a container, you can easily customize your soil mix to create the perfect grow medium for your plants.
Harden off your marijuana plants
If you start your plants inside (in a grow room or on a windowsill), harden them off before transplanting them to an outdoor location. Hardening off is a process in which plants gradually become acclimated to the outside environment over a period of seven to ten days.
Take your plants outside for 30 minutes or so on the first day and place them in a sheltered area where they receive indirect sunlight and perhaps a gentle breeze. Continue to increase this time by 30 minutes or so each day, gradually increasing their exposure to more direct sun. Watch your plants carefully for signs of heavy stress such as burning or wilting. Light stress is good, and it will accelerate the hardening off process, but heavy stress can kill a plant or severely impact its ability to flourish.
You should also harden off your plants against the cold. If frost is possible, keep the plants inside at night. Otherwise, gradually expose them to the cold nights. You may want to place them in a cold frame or under a box or bucket at first to provide some shelter from the cold without having to bring them inside, just be sure to uncover them the next day or they may overheat. Over the course of seven to ten days, they should be able to make it through a cool and frost-free night.
Support and protect your plants
When growing plants outside, you may need to provide them with support and protection from the elements, especially cold and frost as the summer growing season ends.
First, focus on providing your plant with structural support throughout its growth cycle especially in the flower stage. The idea is to provide your plant’s branches the support they need to grow big fat buds without becoming too heavy and breaking off from the main stalk. Bamboo stakes, along with twine or Velcro plant straps, are great and provide a variety of ways to stake your plants, such as the following:
- Place a stake alongside the stalk, and tie the stalk to the stake.
- Place three or four stakes around the periphery of the plant, and tie branches that need support to the stakes. You can also wrap twine around the stakes to create your own “cage.”
- Place a row of stakes in front of or behind several plants, and then tie stakes horizontally to the vertical stakes (or weave them together) to create a trellis. You can then tie branches to the trellis.
About This Article
This article is from the book:
About the book authors:
Kim Ronkin Casey has been a communications professional for more than 20 years and recently took a year-long leap into the world of cannabis as the communications manager for one of the leading dispensaries in North America. She now consults for companies in the industry on internal and external communications. Joe Kraynak is a professional writer who has contributed to numerous For Dummies books.