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Best Compost and Fertilizers for Outdoor Marijuana Plants

Now that marijuana is legal across most of the United States, more people than ever have access to the recreational and medical benefits of this age-old natural herb. Still, news write-ups say dispensaries throughout the nation may be a bit slow to expand their inventories. At the same time, not all cannabis seed strains are going to be available through public sources.

Because of all this, people from California to Minnesota are increasingly considering the benefits of growing their own cannabis crops at home. Doing so gives them greater freedom of choice over the strains they use, more control over the quality of their buds, and a wide range of other advantages.

While numerous factors go into growing marijuana, understanding the best compost and fertilizers for outdoor marijuana plants will undoubtedly help you get more out of your crop. Whether you grow in a greenhouse in Colorado, or just in your back garden in Florida, there are several options are available and not all of them are created equally.

Hashing Out Marijuana’s Nutritional Needs

In essence, marijuana needs a blend of 17 crucial vitamins and minerals. Each one plays a role in how the plants grow, branch out, flower, and become ready for harvest. They also have a hand in bud development and potency.

Some vitamins and minerals fall into the category of macronutrients. This means plants need them in larger quantities, and they’re present in higher concentrations throughout plants’ bodies. Others are micronutrients, meaning plants only require them in small amounts.

Three essential macronutrients are carbon, hydrogen, and oxygen. Plants get these from air and water. All the other nutrients come from the soil, and this is where fertilizer becomes incredibly important. Three of the most critical soil-derived macronutrients for marijuana plants are nitrogen, phosphorus, and potassium, or N, P, and K.


  • Nitrogen: Nitrogen is one of the primary components in chlorophyll, the chemical plants use to complete the process of photosynthesis. This element helps keep cannabis growing during its vegetative stage. It also aids in maintaining the plant’s DNA structure. Nitrogen fosters all the desired traits of the strain you choose to grow.
  • Phosphorus: Though plants need phosphorus throughout their lifecycles, this element is most crucial during the flowering stage. It helps buds develop and grow and is partially responsible for increasing their THC and CBD concentrations.
  • Potassium: Potassium work in several ways to promote plant growth and health. It’s important for nutrient exchange and helps plants generate food and energy. It also ensures they’re able to store excess energy for use when they need it.

Outdoor marijuana plants rely on their soil for the nutrients they need with the exceptions of hydrogen, oxygen, and carbon. Some soil is optimal for plant growth because it already contains all the nutrients your Arizona cannabis garden needs to thrive. Nutrient-rich soil is generally dark brown or almost black in color, and it feels a bit soft to the touch. In other cases, though, you have to intervene.


Potting Soils and Mixes

Some home-based gardeners opt for basic potting soils or potting mixes. These products are meant mainly for plants grown in pots. While they have certain advantages, they’re often not the best choices for growing marijuana.

Potting soils are blends of dirt, nutrients, and organic matter whereas potting mixes contain organic materials but no actual dirt. Though potting soils offer certain vitamins and minerals, they tend to become compacted. This means they won’t drain properly and can prevent oxygen from circulating around the roots of your plants. Potting mixes offer better drainage, but they quickly break down when exposed to the elements.

In most cases, it’s better to forego potting soils and mixes altogether. Your marijuana harvest will benefit much more from other alternatives, such as fertilizers and organic composts.


Standard Fertilizers for Cannabis Growth

Standard fertilizers and soil enrichment products are readily available on store shelves and online. They’re often more expensive than potting soils and mixes, but you get more value for the money. When you’re looking at fertilizers, it’s important to keep the previously mentioned nutrient trinity in mind: nitrogen, phosphorus, and potassium

Fertilizers and other soil enrichment products clearly display the N, P, K ratio on their labels in that particular order. You’ll see three numbers separated by dashes on such products. Several variations exist, including 10-10-10, 5-10-10, and 20-20-20.

These numbers indicate how much of each element is present in the product in question. Fertilizers also contain other essential vitamins and minerals as well as fillers and materials for improving soil aeration and water retention.

Experts often recommend fertilizers with a 20-20-20 nitrogen, phosphorus, and potassium ratio for outdoor plants during the vegetative phase. At this stage, nitrogen will help your cannabis plants grow lots of leaves, and this is vital for drawing in sunlight and carbon dioxide to produce food and energy.

Phosphorus will help strengthen the roots for nutrient uptake and give your plants the upper hand when the time for bud production rolls around. During the flowering phase, you’ll want to switch to a fertilizer with higher levels of phosphorus. Potassium makes plants less vulnerable to diseases and harsh growing conditions.

How to Use Fertilizers

In most cases, it’s best to mix fertilizer granules into the soil in early spring at least a few days before you plant your wholesale cannabis seeds or seedlings. Try to work fertilizers into the soil near the same level your plants’ roots will be. If you mix them in too deeply, your plants’ roots won’t be able to reach them during those first few weeks of growth.

If you choose a liquid fertilizer, avoid fertilizing at the same time you place your plants in the ground. Doing so could burn the roots and hamper nutrient uptake. Wait a couple weeks after planting to apply liquid fertilizers.

For outdoor marijuana plants grown in a garden, you may only need to apply fertilizer once every couple of weeks or so. Those grown in pots might require extra food a couple times a week or more. Autoflowering strains also do not require a great deal of added nutrients as compared to their photoperiod counterparts, mainly due to their smaller size and quicker flowering cycle. Some growers fertilize every time they water their plants, but this is also generally not advisable.

All that being said, countless varieties of fertilizers are on the market. Each one has specific guidelines on its label. If you’re in doubt, there’s no harm in simply following the manufacturer’s instructions.

Above all else, look to your plants for cues. They’ll give you warning signs if they’re malnourished or getting an overabundance of nutrients. Some indications your plants are getting too much or not enough of an essential vitamin or mineral are browning or yellowing leaves, stunted growth, and leaf shedding.


The Downside of Fertilizers

Fertilizers are extremely helpful tools in the world of gardening. They have proprietary blends of the nutrients that plants need to thrive. They’re also simple to use. Still, fertilizers have certain drawbacks as well.

Most fertilizers contain chemicals. Some of those agents have been found to cause cancers and other illnesses. Though most are essentially safe, farming experts and experienced growers alike insist chemical-laded fertilizers can negatively impact the taste and aroma of marijuana’s buds. Because of this, many gardeners prefer a different approach to cannabis cultivation.

Taking the Organic Route

For those who’d rather stay away from chemicals and synthetic additives, composting may be the better alternative. This is a more time-consuming and labor-intensive approach, but it’s completely natural and won’t burn the plants’ roots or negatively alter the buds’ tastes and aromas.

Composting entails mixing organic materials and allowing them to decay over time. It’s the same process used by Mother Nature to create rich soil that’s optimized for growing, but human intervention tends to speed up the process.

Whether you simply create a compost pile in the backyard or purchase a composting bin, there are several materials you can add to the mix to give your plants a healthy boost. Grass clippings and dead leaves make a great base for compost. From there, the possibilities branch out significantly.

Save any raw fruit and vegetable peelings and scraps for your compost pile rather than tossing them into the trash. You can also rinse and crush eggshells to mix into the pile. Used tea bags, coffee filters and grounds, and shredded brown paper bags make helpful additions as well.

Some composters dig up earthworms from their yard to put them into the compost bin because they add helpful bacteria and aid in aeration. Other products you can add include fish emulsion, bone meal, blood meal, chicken litter, and cow or bat manure. All these items have valuable properties that add nutrients and break down organic matter. In turn, they’ll help give soil the right consistency to hold water, drain well, and allow for ample airflow around your plants’ roots.

Avoid adding meat scraps and dairy products to your compost pile. Animal-based products will add unhealthy bacteria to the mix and cause odors, and they’ll ruin your compost rather than helping it along. Compost piles can take six months to a year to become ready to use but turning them often will help speed the process.

All Things Said and Done

You have plenty of options for giving your cannabis plants the nutrients they need to grow, thrive, and produce loads of potent buds. Fertilizers are the simplest options available. They provide carefully balanced mixtures of the nutrients your plants need, and they’re simply added to the soil at regular intervals.

Compost offers a more natural alternative. Creating compost takes a certain amount of time, effort, and patience, but the end result lacks harsh chemicals that could potentially detract from your buds’ flavor and aroma or have other unpleasant effects.

Either way, the techniques you use for enriching the soil around your cannabis plants should not only add in nutrients but foster oxygen circulation around the roots and aid in water retention. In the end, you’re bound to reap a bountiful harvest as well as all the benefits those buds hold in store. Try our high-CBD seeds or the 710 seeds which are high in THC and perfect for making oil and concentrates.


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