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How To Grow Big Cannabis Plants Outdoors

When you’re looking to grow big cannabis outdoors, both size and what you do with it are important. Fear not if your outdoor cannabis plants look more like Kevin Hart than The Rock. With the right tips, you’ll soon be gazing out over some serious size.

If you’ve ever browsed weed-related social media accounts, you might’ve marvelled at the hulking green majesty of the cannabis trees grown out in California. Unless you’re a seasoned cannabis cultivator, you’ve no doubt wondered how they do it, too.

Unfortunately, it’s not just a case of buying special cannabis tree seeds and following the usual steps. But there’s good news! By reading this article and following the guidelines, you, too, can grow cannabis outdoors that will dwarf your neighbour’s poplars.

Big Cannabis Begins With The Right Strain

As with any project, quality genetics is the best place to start. Opt for photoperiod strains, as autoflowering cannabis is engineered to produce smaller plants. You’ll still get cracking cannabis from autoflowering strains, sure. But if it’s the sheer size you’re after, photoperiod cannabis strains are the best choice.

Have a clear idea of what you want from your cannabis in terms of flavour and effects, and hop to Seedsman’s strain finder. From there, look for the tallest-growing, highest-yielding cultivars. Get those cannabis seeds added to your basket for a good head start.

Grow Big Cannabis Plants Outdoors

Pictured above: Seedsman’s Badazz OG Cheese

If this is your first time growing big plants, it’s common sense to start with only one or two. Growing one plant makes it easier for you to monitor and address any issues. By growing two, you at least have a backup if one should ail beyond rescue. Avoid biting off more than you can chew initially, as the logistics alone involve a significant step up.

Should You Use Indica or Sativa for Big Cannabis Plants?

The anatomy of each is very different. If you’re somewhat new to growing marijuana, it helps to know the differences between the two main plant types. Indica and sativa may share similarities, but when it comes to stature, there are some contrasting physical characteristics.

Basic Anatomy of Cannabis Sativa

Sativas are typically taller, making them good for producing the kind of height you’ll want on a project like this. They have narrow leaves, so while they can stretch up the way, you might find they leave you wanting more in terms of the bushy appearance.

Cannabis sativa has a longer flowering cycle than indica and is suited to warm outdoor climates.

Basic Anatomy of Cannabis Indica

Indicas tend to produce a shorter plant than sativa. While the right techniques can help the stretch, they’re less likely to achieve the sheer height you’ll want to see in a cannabis ‘tree’. They have broader leaves than sativas, an advantage in terms of achieving that full, bushy look you’re going for.

Cannabis indica has a shorter flowering period and is better suited to growing in a cooler outdoor climate with a shorter season.

Hybrid cannabis strains combine the best of both worlds. Through selective engineering, breeders have taken the best features of both types of cannabis and combined them to make exciting new strains. These hybrids contain the most favourable properties of each strain used in breeding, like the high-yielding properties of one strain and the resilience of another.

By selecting the right hybrid genetics from the outset, you can get a head start on growing monster cannabis plants. Choose a sativa-dominant strain if height is your preferred attribute and an indica-dominant hybrid if you prize more of the full, bushy appearance. Either way, a hybrid will provide you with both qualities in suitable abundance.

You Need Space to Grow Big Outdoors

Space may be the final frontier, but it’s the second step to growing big weed outdoors. Having sufficient room for your plants to grow is key for several reasons:

  • The more space the roots have, the bigger they will grow
  • Bigger roots mean bigger plants
  • The plants themselves will need space to stretch upwards and outwards

Once you’ve settled on a garden area, make sure you leave plenty of growing space between plants – think metres instead of feet. Look at pictures of similar projects online, and you’ll notice plants are spaced significantly further apart than conventional cannabis grows. Remember to pick a site that receives the most direct sunlight and is relatively shade-free.

Grow Big Cannabis Plants Outdoors

Pictured above: Seedsman’s Alaskan Purple

Big Outdoor Plants Need Big Outdoor Pots

It goes without saying, but we’re saying it anyway – you need huge pots to accommodate the plant and its roots. This is vital to growing big plants efficiently. You’ll need smaller pots for your seedlings, post-germination, of course – but you’ll need to level those up, too. Once you see roots appearing under the pot, you need to transplant them to larger pots to allow them to grow, and you need to do that as soon as possible.

For massive cannabis plants, you’re looking at needing anywhere between 1000L and 1500L of substrate per plant to allow the root system to grow sufficiently. This will accommodate the kind of vigorous growth necessary to produce awe-inspiring size. Failure to give your plants the type of space and amount of substrate they need will only inhibit the growth and yield of the plant. All aspects of the game are being levelled up for this project, so you mustn’t cut corners. Think big, always.

Geotextile pots are a favourite of Californian growers – they not only have the kind of size you need, but they also create a well-aerated environment, meaning plants have more oxygen. This ramps up the plant’s metabolism and capacity for growth.

To Grow Cannabis Trees, Consider Soiling Yourself!

Many Californian growers specialising in huge cannabis plants use a homemade substrate called ‘Supersoil’. This well-oxygenated soil contains all the necessary nutrients for optimal plant growth. To truly go organic, you may want to follow the Cali example. How much you need obviously depends on how many plants you want to grow, but the rule of thumb for Supersoil is to use 1000L-to 1500L per plant.

A small disclaimer: The downside is that this is a considerable undertaking if you’re hoping to produce several plants. Making your own Supersoil will require some budget and heavy lifting. Ensure you have the necessary means and physical capability (really!) to distribute this soil and transport it when needed – shovels, wheelbarrows, and a few extra pairs of hands will make this a good bit easier on your spine.

Producing good soil on your own is doable, but it’s far from a cakewalk. If you’re willing to invest the time and effort, here’s a recipe you can follow:

  • 30% white peat
  • 30% black peat
  • 10% perlite
  • 10% coco coir
  • 10% sphagnum moss
  • 10% vermicompost
  • Mycorrhiza and Trichoderma (to apply in roots when you’re repotting)
  • A top layer of Biochar and straw to prevent evaporation from the surface

Putting a thin layer of diatomaceous earth works as insulation but carries the necessary advantage of repelling parasites such as substrate flies. It will also help keep larvae from feeding on the root hairs, which would inhibit root growth and ultimately hinder plant growth.

Grow Big Cannabis Plants Outdoors

Pictured above: Seedsman’s Purple Ghost Candy

The Main Stages

To maximise plant growth, it’s important that you do things a little differently during the different growth stages of your plant’s growth cycle. When looking to grow marijuana plants of behemoth proportions, the most important thing is to prepare correctly and then wait.

Germinating your seeds should be carried out indoors and well ahead of the growing season, with February being an ideal time to carry out this stage. By germinating this early, you can develop your seedlings indoors under artificial lighting to give them a good head start. This is all about establishing the plant and its hardiness before taking it into the outside world. A plant must be robust to reach the lofty heights of 8 feet-plus that you’re seeking and starting indoors under grow lights will build a solid template for that big growth. Once the plant is well established and strong, get it outside and straight into your growing medium. Transplant them outdoors nice and early if your climate allows, giving them a prolonged growing season under favourable conditions.

Grow Big Cannabis Plants Outdoors

Pictured above: Seedsman’s Peyote Gorilla

When growth/vegetation is underway, ensure your plants receive a photoperiod of 18/6 but watch for roots that appear underneath. This means the roots don’t have adequate space to flourish. As soon as this is obvious, you’ll have to transplant your cannabis into bigger pots; otherwise, you’ll stunt their growing ability. You may find this happens regularly, so prepare an array of pots of differing sizes to accommodate that bumper growth.

Moving plants to bigger pots is an uphill task. It’s heavy work, and assistance is preferable for this portion of the operation. You want to keep your plants safe and steady and minimise the risk of any damage.

Consider a root growth stimulator once a week, and use compost tea to stimulate plant recovery after transplanting your babies.

The Vegetative Stage – Key to Achieving Size

To gain an advantage in growing sizable cannabis, you’ll have to extend the vegetative stage of the growth cycle far beyond what you ordinarily would. With adequate space for root growth, the plant will continue to grow, and this is perhaps the key component in achieving tree-like proportions. How long to extend it for, unfortunately, varies with the type of genetics. Still, you may go as long as 8 weeks into an indoor vegetative phase before finally shifting your plants outdoors.

Prepare your soil in advance of the shift. This way, your plants can be placed in top condition once you plant them outdoors. You can give your plants up to two months of outdoor light and climate to further develop.

Depending on your location, you might consider ending the flowering phase early to avoid mould issues in the autumn months. The flowering stage is important, but seasonal changes bring potential problems.

Feeding and Watering For Maximum Growth

It stands to reason that plants need more food and water to pack on mass. While there many ways to go about this, the key is to follow the manufacturer’s guidance on feeding. Make sure to adapt feeding in accordance with the growth phase and climate.

Watering plants of this size is different to regular practices, too. Plants – or trees – need a great deal of water, but the spectre of overwatering issues still looms large. Aim to supply your plant with about 10-20% of the pot’s size worth of water, ensuring you don’t leave plants sitting in a pool of run-off water.

Avoid the temptation to gorge your big plants with a huge influx of nutrients from the outset. It’s more important to let healthy roots develop, so build up nutrients initially. Start with around a quarter of the strength, to begin with, and make incremental increases as your plants develop. Too many nutrients can cause as many problems than too few. Remember, organic fertilizer is more forgiving than liquid nutrients and make a safe alternative the liquid variety. Microorganisms can also be helpful, so use these to your advantage.

Training Techniques For Big Outdoor Cannabis

You’ll need adequate support for your plants. There are a number of ways to go about it.

Use stakes near the plant’s main stem to help support the structure and encourage vertical growth. Otherwise, you’ll find issues when your plant begins to stretch. Nets or trellises are also advised, as your plants will take on the kind of stature that will benefit from as much control as possible. By employing nets, you can support the top of the plant around the main cola and upper branches for additional structural support.

Topping your plants is a good technique to redirect energy away from the main central branch and toward competing branches. This allows for more uniform development and greater overall growth and bud production. There’s no sense growing just for sheer size – you still want to ensure your plant produces excellent yields.

Pruning your plant can assist similarly. As the lower areas of plants don’t receive the same amount of sunlight, judicious pruning will allow more light to penetrate the canopy. This will facilitate serious growth and enhance bud production but offers benefits for your plant’s survival. Big, bushy trees will likely contain pockets of still air in the inner areas, which can wreak havoc in terms of mildew or mould. Pruning and defoliation techniques will create essential airflow in areas of the plant that will let your cannabis breathe.

Final Thoughts on Growing Big Cannabis Plants Outdoors

Invest in some tree ladders. Once your plants take stretch, your tiptoes alone won’t give you the access you need. Getting there without causing structural damage to the plant itself may be challenging. Research and find the method that suits you to work in the upper sections.

One of the benefits of the social media age is that you can view other people’s results and ask questions. Be meticulous in your research on outdoor cannabis growing, and do a little homework on strains before buying your seeds. Watch videos online, view grow diaries and look at the photographs. This will help you see how the cultivators who have already achieved the results went about it. It’ll also give you a good insight into which strains performed the best.

Good luck, and if you decide to give growing big marijuana outdoors a try, be sure to share your results for us to see!

Grow Big Cannabis Plants Outdoors
Cultivation information, and media is given for those of our clients who live in countries where cannabis cultivation is decriminalised or legal, or to those that operate within a licensed model. We encourage all readers to be aware of their local laws and to ensure they do not break them.

Duncan Mathers