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Best Soil for an Outdoor Cannabis Garden

Correctly preparing the soil for an outdoor cannabis garden can make all the difference to the quality and size of your eventual harvest. Cannabis has specific requirements in terms of soil quality and texture. Here is a brief guide to ensuring all variables are optimized.

Choosing the best soil for cannabis means monitoring soil acidity, texture and pathogens or pests inherent in soil. Making your own soil or purchasing sterile soil gives you full control over the acidity, nutritional content and texture of the soil. At the same time, planting in the ground exposes cannabis plants to the entire living organism that is soil — and this is very difficult to create in a pot.

In any case, the growing medium is fundamental to the grow itself as well as the final harvest. Having well prepared soil can help a grower mitigate problems throughout the grow. Theoretically, if soil is well nourished, the plant should thrive with little intervention. A healthy plant necessarily starts with great soil, and without the optimum soil for growing cannabis, you will never be able to bring about an optimum harvest.

Soil texture and composition for outdoor soil

The best soil texture for cannabis is light, loamy soil that drain swell but also retains a degree of moisture. Loamy soils are a mixture of sand, silt and clay in an approximately 40:40:20 ratio:

  1. Sand is a major constituent of many soils, and is characterized by granular particles of rocks and minerals that measure 0.05mm to 2mm in diameter.
  2. Silt is finer than sand, and consists of particles measuring 0.002mm-0.05mm.
  3. Clay is finer still, and its particles measure less than 0.002mm in diameter.

One method of determining soil composition involves shaking soil in a jar full of water and allowing the particles to settle; a more detailed explanation can be found here.

The smaller the average particle size in soil, the harder it is for water to travel through it. You can think of it like a coffee machine. If you pack the coffee into the wand too tight, it’s near impossible for the water to come filtering through. By the same principle, sandy soils have very quick water drainage, while soils with high clay content become waterlogged easily.

If you’re using natural local soil, you can mix extra sand, silt or clay into it to improve its soil draining or retaining capabilities as needed. Drainage and soil stability may also be improved by adding gravel, which in technical terms is rock and mineral particles measuring 2m-75mm in diameter. Larger rocks can be removed where possible to avoid causing obstruction to the roots of plants.

If soil is poor, you may wish to consider buying good-quality commercial soil and mixing it into existing soil. You can also add manure, mulch, bloodmeal, bonemeal, or a range of other soil additives designed to improve nutrition release. You can even grow your plants entirely in bought commercial soil, in bags or pots so that they are not exposed to local soil.

Regulating pH of soil for growing outdoors

The optimum pH range for cannabis is between 5.5 and 6.5, making it slightly acidic. If soils are more acidic or alkaline than this, a range of deficiencies or toxicities can result. Soil that is too acidic or too alkaline disturbs a plant’s ability to absorb and use nutrients. If nutrients are not taken up in optimum ratios and quantities, your plants will not achieve the maximum quality and yield, your final harvest will suffer as a result.

Soil pH can be adjusted with a pH regulator. This is usually a solution that can be purchased from any gardening store. The most commonly used ingredient to lower pH (make it more acidic) is sulphur. Sulphur reacts with specialized bacteria commonly found in soil to create sulphuric acid, therefore acidifying the soil.

To increase pH, agricultural lime is usually added to soil. However, it isn’t necessary for cannabis cultivators to purchase sulphur or lime. These are usually available in solution at garden stores. A thorough guide to adjusting pH can be found here.

Remember that before you add a pH regulator to your soil, you first must know the current pH of your soil. This is measured with a soil pH meter. It can also be purchased from your garden store. You should only add pH regulator to your soil once you know the current state of acidity.

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How to Choose the Best Outdoor Cannabis Strain

Sterilizing your outdoor soil

Sterilizing your soil by exposing it to steam can kill off many harmful bacteria, fungi and insects, while allowing several beneficial bacteria to remain alive. If purchasing good-quality commercial soil intended for growing cannabis, it is usually unnecessary to sterilize soil. However, if using local, natural soil, it may be helpful to sterilize where possible. It may also bring the added advantage of killing off any unwanted weed seeds present in the soil.

Sterilizing is a difficult and time-consuming process that is often overlooked though. If it’s not feasible to conduct this step, there are other ways to control pests. You can introduce beneficial microbes and insects to soil, as well as organic, plant-based compounds that repel or kill pests without harming the plant.

There are various techniques for sterilizing outdoor soil. Solarization is one method, and involves thoroughly tilling the soil so that it is broken up into fine pieces, watering and covering with a sheet of clear plastic.

The sheet of plastic amplifies the heat and light of the sun and allows the soil to reach high enough temperatures to kill off most undesirable microorganisms. Soil must reach temperatures of 46°C (114°F) for four to six weeks to be fully effective. It should be checked and re-tilled regularly to ensure that temperatures are sufficient and consistent.

If soil solarization is not possible due to time constraints, it may be possible to sterilize your soil by using steam. Large-scale agricultural operations make use of expensive, specialized equipment, but it is possible to use cheaper household sources of steam such as a pressure cooker to sterilize soil.

There are also methods that have been designed for smaller-scale grow operations. For example, the Hoddesdon grid method is a technique that involves layering tilled loam on a steel grid over a shallow pan of constantly-boiling water so that steam can rise through it. When temperatures reach 82-88°C (180-190°F) throughout the soil, sterilization is complete.

Growing outdoors: Pots, bags, or holes in the ground?

When growing outdoors, there are several options available: grow your plants in pots or planters, keep them in growing bags (which may be the plastic sack your commercial soil was purchased in, or may be specially-designed bags that are typically made of hessian or breathable plastic). You can also dig holes in the ground and plant directly into the soil. Outdoor soil can be optimized using the methods outlined above, or use without modification if testing shows it to be naturally optimized for growing cannabis.

If growing in pots or bags, you have the advantage of using commercially-bought soil which is not only optimized for growing cannabis but pre-sterilized to ensure that no harmful microbes are present. The downside is that your plants will be constricted by the size of their container. Pots may also require regular transplants as well as water (which they cannot receive from groundwater as plants in permeable bags or holes in the ground can).

On the other hand, digging holes in the ground and planting your young plants straight into the soil allows them to grow without constraint, and will allow roots to access the maximum amount of groundwater. Thus, they will achieve larger sizes and will require less vigilant maintenance, but may be at increased risk of exposure to soil pathogens and even contamination from agricultural run-off, for example.

Choosing the best soil for cannabis is often not as complicated as growers make it out to be. This is especially true for those who are just beginning to grow cannabis, and are not particularly concerned with yielding specific amounts of specific cannabinoids. Cannabis grows almost everywhere, and is known to grow in wet soil next to riverbeds as well as on rocky mountainsides. Well-nourished soil with the correct texture and pH is the best starting point, after which many adjustments can be made throughout the grow using nutrients and pH regulator.

Watch your plants throughout the grow, and adjust the soil as need be. Growing cannabis is a learning process that requires time and patience, and the best things are learned on the job!

Prepping the soil for an outdoor cannabis garden makes all the difference. Learn about the small details that make a high-quality harvest.

How To Create Your Own Cannabis Super Soil Mix

Your buds are only going to be as good as the plants that bear them. And the best way to grow big, healthy cannabis plants is to use homemade super soil rich in nitrogen, phosphorus, potassium, and other vital nutrients.

Making a homemade cannabis super soil mix is much more rewarding than buying store-bought soil and bottled nutrients—and it’s not that difficult to make.

  • 1. What are the pros and cons of making your own super soil?
  • 1a. Pros
  • 1b. Cons
  • 2. Understanding soil and cannabis nutrition
  • 3. How to prepare your own cannabis super soil mix
  • 3a. Buy your base soil
  • 3b. Enrich your soil
  • 3c. Wash your super soil (if you want to plant right away)
  • 3d. Don’t plant directly into homemade super soil
  • 1. What are the pros and cons of making your own super soil?
  • 1a. Pros
  • 1b. Cons
  • 2. Understanding soil and cannabis nutrition
  • 3. How to prepare your own cannabis super soil mix
  • 3a. Buy your base soil
  • 3b. Enrich your soil
  • 3c. Wash your super soil (if you want to plant right away)
  • 3d. Don’t plant directly into homemade super soil

Store-bought soil works fine for growing cannabis, but it’ll only get you so far. To grow the best cannabis at home, we recommend always preparing your own soil. Keep reading for step-by-step instructions on how to prepare your own cannabis soil mix.

WHAT ARE THE PROS AND CONS OF CREATING YOUR OWN SUPER SOIL?

Like many aspects of growing, there are a number of pros and cons to creating your own cannabis soil. The pros, however, far outweigh the cons, and we encourage every grower to try preparing their own soil at least once.

• Good-quality homemade soil is rich in both macro and micronutrients, meaning you’ll be less reliant on chemical fertilisers.

• Growing with homemade soil gives you complete control over where your plants get their nutrients from. If you’re looking to grow organically, this is the way to go.

• Bud grown without chemical nutrients delivers a big, natural flavour like no other. A tastier, smoother smoke can be expected.

• The chemicals found in nutrient solutions create harsh runoff that can have a devastating effect on the local environment. On the other hand, using your own, homemade soil is completely sustainable and environmentally friendly.

• Preparing your own soil takes time, which is a luxury not all growers have.

• Preparing your own soil requires a larger initial investment than if you simply bought regular soil and a few nutrient solutions. Keep that in mind if you’re growing on a budget, but also remember that the results are definitely worth it.

UNDERSTANDING SOIL AND CANNABIS NUTRITION

Soil plays two key roles in the cannabis cultivation process. First of all, it weighs down your cannabis plants, keeping them rooted and protected against the wind. Secondly, and more importantly, it serves as a medium to transport nutrients and water to your plants’ roots. To better understand soil and how we can use a homemade mix to fertilise and nurture our cannabis plants, it helps to understand the basic nutrients cannabis plants need to survive and thrive.

Besides water, cannabis needs three main nutrients or _macronutrients_: nitrogen (N), phosphorus (P), and potassium (K). When you buy fertilisers, you’ll find products with varying concentrations of these nutrients designed to be used during different stages of the grow cycle. Here’s a brief rundown on how these nutrients help cannabis plants grow:

• Nitrogen is one of the main components of chlorophyll, and an essential building block of important amino acids.

• Phosphorus is essential for the production of ATP and phospholipids, which are used to build cell membranes.

• Potassium helps enable photosynthesis, regulates CO₂ uptake via stomata in a plant’s leaves, and helps strengthen cell walls.

Nitrogen, phosphorus, and potassium make up the bulk of the nutrients in most fertilisers you’ll find at a gardening store or grow shop. However, there are many other nutrients, known as micronutrients, that also play key roles in keeping your plants healthy and helping them produce the best possible buds.

Some of these micronutrients include calcium, iron, sulfur, zinc, boron, manganese, and copper, which you’ll find naturally in things like bat guano, worm castings, molasses, kelp, coffee grounds, and more.

When you prepare your own super soil for cannabis, you have the opportunity to prepare a rich medium for your plants ahead of time, rather than feeding your plants on an as-needed basis using chemical fertilisers. The hard work and effort you put into preparing your own natural and organic soil before sowing your seeds will pay off big time in terms of flavour and quality come harvest.

HOW TO PREPARE YOUR OWN CANNABIS SUPER SOIL MIX

Preparing your own super soil might sound daunting, but it really isn’t. The concept is, in fact, pretty simple; you’ll start off with some good-quality organic soil and enrich it with natural ingredients ahead of time. Once it’s time to sow your seeds, you’ll have a rich growing medium ready that will provide your plants with everything they need to produce beautiful, aromatic buds.

STEP 1: BUY YOUR BASE SOIL

Picking the right base soil for your cannabis plants is super important. Remember, cannabis likes well-aerated, permeable, and slightly acidic soil (pH of 6–6.8 is ideal). If possible, you’ll want to opt for an organic soil containing natural ingredients like worm castings, compost, coco coir, sand, and more. While these soils are generally more expensive, they’ll make a notable difference to the health of your plants and the quality and size of your harvest.

Some other ingredients to look for in organic soils include:

• Peat moss
• Guano
• Manure
• Rock dust
• Sand
• Coco fiber
• Natural fertilisers (like K-Mag)
• Pine castings
• Perlite
• Vermiculite

If you can’t find a good-quality organic soil with at least some of these ingredients, don’t fret. Simply go to your local nursery or gardening centre and buy a neutral potting soil. Again, opt for something slightly acidic if possible.

STEP 2: ENRICH YOUR SOIL

Start by placing your soil in a big container; break it up with a graip to ensure it’s well-aerated. Once it’s nice and loose, you’ll want to get to work enriching your soil with more natural ingredients to create a rich growing medium for your cannabis plants.

Some things to add to your soil include:

  • 1. Worm castings
  • 2. Coffee grounds and/or tea leaves
  • 3. Eggshells
  • 4. Vegetable and fruit peels
  • 5. Compost
  • 6. Coco coir
  • 7. Perlite
  • 8. Vermiculite
  • 9. Sand
  • 10. Bone meal
  • 11. Blood meal
  • 12. Rock phosphate
  • 13. Epsom salts
  • 14. Lime
  • 15. Dolomite
  • 16. Organic fertiliser pellets
  • 1. Worm castings
  • 2. Coffee grounds and/or tea leaves
  • 3. Eggshells
  • 4. Vegetable and fruit peels
  • 5. Compost
  • 6. Coco coir
  • 7. Perlite
  • 8. Vermiculite
  • 9. Sand
  • 10. Bone meal
  • 11. Blood meal
  • 12. Rock phosphate
  • 13. Epsom salts
  • 14. Lime
  • 15. Dolomite
  • 16. Organic fertiliser pellets

Simply add these ingredients to your soil and use your graip to combine everything properly.

The “correct” amount of each ingredient you use in your super soil will depend on the quality of your starter soil and how much time you have before planting. If possible, prepare your soil at least six months before you plant. That way, you’ll be able to use more of the ingredients listed above as they’ll have time to break down properly.

Once they do, they’ll create a rich topsoil for your plants, similar to what they’d have in nature. This super soil will be rich in nitrogen, phosphorus, and potassium, as well as all the other micronutrients we mentioned earlier.

This process, however, takes time. Compost, for example, can take anywhere from a few months to years to be ready, and you’ll need to take that into account when planning your grow. Vegetable or fruit scraps alone can take a few months to break down.

If you want to plant straight away, you can still use some of the ingredients listed above. You’ll just need to be more careful as you’ll be at risk of creating a really nutrient-rich (or “hot”) soil that can actually burn your plants. As a general rule of thumb to get you started, try using the following ratios of soil and other ingredients:

– 4 parts starter soil
– 1 part worm castings
– 1 part coco coir
– 1 part perlite/vermiculite (for extra drainage)
– 2.5–5% guano
– 2.5% bone and/or blood meal

When adding micronutrients like epson salts, azomite, lime, and dolomite to your soil, always read the package instructions. These nutrients are really strong and can cause nutrient burn when not used properly.

STEP 3: WASH YOUR SUPER SOIL (IF YOU WANT TO PLANT RIGHT AWAY)

If you don’t have months to prepare your own super soil, here’s a simpler, faster way to prepare your own cannabis soil at home.

In the pots you plan to grow in, combine:

– 3 parts organic starter soil
– 1 part perlite
– 1 part worm castings
– ½ cup greensand
– ⅓ cup guano
– ½ cup dolomite lime

Mix everything together using your graip, then soak the soil for at least two days in pure water, keeping it wet all throughout. This will ensure your soil isn’t too hot for your seedlings. Allow the water to run off and the soil to mostly dry before planting. Once you do plant, make sure to use just plain water for at least the first three waterings.

STEP 4: DON’T PLANT DIRECTLY INTO HOMEMADE SUPER SOIL

It’s really important to note that homemade super soil is very nutrient-rich and shouldn’t be used for seeds, seedlings, or clones. These young plants are very delicate and will suffer from nutrient burn in such a hot medium. Instead, you’ll want to germinate your seeds and keep your young plants in neutral soil for at least the first few weeks, only transplanting them once they’ve officially started vegging.

Stop growing weed with crummy store-bought soil. Click here for step-by-step instructions on how to easily prepare your own cannabis soil at home.