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Grow Healthy Marijuana with Optimum Yields

What Do Marijuana Plants Use to Grow Well and Produce Optimum Yields?

Cannabis is becoming an increasingly important crop across the nation. No doubt, as more states legalize the use of this age-old herb, growers will continue to take greater interest in its cultivation. While marijuana is a relatively simple plant to grow, producing substantial, high-quality yields isn’t so simple. Given the number of strains now available, working out how to grow a healthy and high-yielding plant requires some fundamental cultivation knowledge.

Understanding the Essentials for Cultivating Cannabis

All types of plants need certain fundamental elements to grow well and produce high yields. Marijuana is no different. Its basic requirements are water, light, heat, nutrients and air. Of course, quite a few considerations enter the mix under each variable. In order to fully understand the needs of your marijuana crop, it’s important to break down each requirement into its key elements.


Like humans, plants require a balance of certain vitamins and minerals in order to thrive. Seventeen specific nutrients are vital to plant health. Some are classified as macronutrients whereas others are micronutrients.

Cannabis plants need large amounts of macronutrients, such as nitrogen, phosphorus, potassium and sulfur. Potassium plays a major role in osmoregulation, and helps roots develop well so they can support the plants and aid in nutrient uptake. Appropriate amounts of nitrogen help stalks and leaves develop during the vegetative phase while phosphorus boosts growth during the flowering phase.

Micronutrients are minerals needed in smaller volumes, such as chlorine, iron, copper and zinc. Though plants don’t need large volumes of these minerals, a lack of them could lead to developmental issues and smaller yields among other problems.


In addition to vitamins and minerals, marijuana plants need light. Cannabis uses CO2 and light to create food via photosynthesis. Photo means light and synthesis means creation, so for plants, photosynthesis is literally the act of using light to make food. Without light, plants quickly die.

So, chlorophyll, the compound in plants’ leaves that makes them green, converts CO2 and sunlight into glucose. Different types and amounts of light are required depending on the stage of growth. During the seedling and vegetative phases, marijuana plants need more blue-spectrum light, while the flowering phases call for higher exposure rates of red-spectrum light. The Emerson Effect is a lighting technique used during the flowering phase, and involves two different red-spectrum wavelengths (deep red and far red) that are exposed to the plant concurrently—a technique that closely mimics the quality of sunlight plants receive in autumn months. The photosynthesis  while the plant is flowering, which significantly and is featured in some LED light setups.


Water is arguably the most important element for sustaining life on Earth. Every living thing needs water in order to survive, and cannabis is no exception. Water accounts for as much as 80% of a marijuana plants’ total composition, and it plays several key roles in health and growth.

Without the oxygen from water, roots can’t draw in enough nutrients from the soil to effectively feed the plants. Inadequate oxygen levels in the soil can also make plants more vulnerable to root rot, fungal growth and other problems. Also, water dissolves nutrients in soil or growing media, decreasing the size of nutrient particulate, allowing the plant’s roots to absorb nutrients more easily. Another important contribution from water is the pressure it causes, forcing upward movement of both water and nutrients into the branches, stems, and flowers.

At the same time, water passes through a plant’s cells via vacuoles, which acts like tiny bladders providing pressure, structure, and strength. This becomes increasingly vital as marijuana grows and blooms. After all, the more they grow, the more water they need to maintain their structural integrity and support their flowers until harvest season. Cannabis plants have varying water requirements depending on the strain and phase of growth, so researching the specific water requirements of each plant is ideal!


When it comes to temperature, marijuana plants are a bit like cold-blooded animals. They thrive in warmth because a certain amount of heat helps promote photosynthesis and transpiration, which is the process through which plants breathe. In much cooler environments, though, cannabis tends to shut down and stop growing because cold temperatures tend to shock the plant.

Although cannabis plants need warmth, extreme heat can be as detrimental as extreme cold. When temperatures climb too high, plants often lose more moisture than they’re able to draw in. This is the reason they sometimes wilt in hot, dry weather. For most marijuana strains, the optimum temperature range is between 68 – 78°F, although optimal temperatures vary between strains.


Marijuana plants also require carbon dioxide (CO2) and hydrogen (H) from the air. CO2 combines with water (H2O) in the chloroplasts where the elements are converted into food (glucose) for the growing plant.

Venturing beyond the Basics of Cannabis Cultivation

We’ve covered the essentials for cannabis growth. Still, plenty of details lie beneath the surface. How much, and at what time intervals, does the cannabis plant require these basic environmental variables? When does enough become too much? Perhaps most importantly, where do the variables come from?

Giving Marijuana Plants the Nutrients They Need

Traditionally, marijuana plants draw their nutrients from soil. Some dirt just isn’t composed of adequate vitamins and minerals to support the needs of cannabis. It’s certainly possible to test your soil to find out if it’s suitable for growing. The process takes some patience and effort, but nutrient testing kits are readily available at home improvement stores, horticulture centers, and online.

Nutrient testing may not be necessary, though. Color is usually a good indication of whether the soil is capable of supporting optimum plant growth. Soil that’s dark brown or black tends to be rich in the nutrients marijuana plants require.

Enhancing the Soil

Soil that’s light brown or has a sandy texture isn’t quite ready to nurture plants. If sandy soil is the only option, consider adding fertilizer or compost to the mix before planting. This will enrich the soil and make it more suitable as a growing medium.

Clay soil isn’t recommended for growing marijuana, either. It has a high mineral content, but it often lacks vitamins. It’s also too dense and sticky for cannabis roots to penetrate. Though clay holds moisture well because of its texture, it doesn’t drain quickly or completely enough to allow roots to breathe. All these factors make for a less-than-favorable growing medium.

If clay soil is the only option, it’s possible to make it suitable for cannabis cultivation. Mixing in compost, dead leaves or grass clippings will add more organic matter to the soil and improve its overall composition. Adding perlite will promote airflow and drainage. Manure will also add much-needed nutrients. Prepackaged, deodorized varieties are available if you’re opposed to the smell of manure.

It’s best to mix those supplements into the soil well in advance to planting your marijuana to allow them time to mix and balance into the substrate. The pH levels will be affected by supplements, so keep an eye on pH levels as they indicate how acidic or basic the soil is. Cannabis usually grows best in soil with a pH of 6.0 – 7.0. Testing kits are available to check soil pH, and if the test reveals the soil is too acidic or too basic, you can purchase products to adjust it accordingly.

Shedding Some Light on the Situation

When grown outdoors during the right seasons, cannabis gets all the light and heat it needs from the sun. This full-spectrum sunlight gives plants much of the energy required for photosynthesis. Natural light from the sun varies in color and intensity according to the time of year and time of day. Marijuana plants take in the portions of the light spectrum they need at specific times to encourage stalk, foliage, and flower growth.

Indoor cannabis plants must take in light and warmth from grow lights that produce synthesized light. Several types of grow lights are on the market, each one geared toward plants’ various needs. Compact fluorescent bulbs come in assorted wattages and give off different spectrums of light. Since they don’t burn quite as bright and hot as other grow lights, you’ll need to place them closer to your plants. If the lights are too far away, the plants will stretch toward the lights, weakening the branches.

Conventional fluorescent bulbs are often used for indoor growing as well. They generate more heat than their compact counterparts, so they should be placed further away from your marijuana plants. Both types of fluorescent bulbs can provide the full spectrum of light, so they work well for all growth stages.

For growers who want to take a more in-depth approach to indoor marijuana cultivation, metal halide (MH) grow lamps are best for cannabis’ vegetative state because their blue spectrum light closely resembles the dominant spectrum of early-summer sunlight. High-pressure sodium (HPS) lamps offer red spectrum light, which is the dominant spectrum of sunlight during autumn, so HPS lights with their red wavelengths contribute to optimum growth during the flowering phase.  Some growers use both MH and HPS, each for the optimal spectrum of light they can provide during specific stages of growth.

Color and intensity are important qualities pertaining to light but giving your cannabis plants the correct amount of light is also crucial for producing optimal yields. Most strains require 18 hours of light and 6 hours of darkness per 24-hour period during the vegetative state. When they reach the flowering phase though, they need about 12 hours of light followed by 12 hours of darkness per 24-hour period.

If growing indoors, be sure to monitor the temperature of the lights and adjust their distance from the plants as needed. You may need to use exhaust fans to help regulate temperatures. This is especially true if you’re using fluorescent, metal halide (MH) or high-pressure sodium (HPS) grow lamps, or have several plants in a small indoor space.

Watering Your Marijuana Plants

First-time cannabis gardeners often seek out specific formulas for determining how much water their plants need and how often. In most cases, though, it’s impossible to dictate exact volumes and frequencies because of all the variables in different strains and growing conditions. It’s usually best to simply keep an eye on your plants and give them water as needed.

During the germination and seedling stages, marijuana needs significant amounts of water. During these beginning stages, soil can remain consistently moist by adding small amounts of water 2 – 3 times each day.

Once the plants have been growing for 4 – 8 weeks, they’ll need less water. They may only need to be watered once every 2 – 3 days. If the soil is moist an inch below the surface, it is saturated enough to hydrate the plant. These standards apply to the flowering phase as well.

Be sure to take note of any signs of dehydration in your marijuana plants. If they’re brown and wilted and their soil feels dry, they probably need more water. Should they appear yellow or withered despite being adequately watered, they could be getting too much water. Alternatively, they might be getting too much or not enough nutrients. Both nutrient burn and nutrient lockout present symptoms like dehydration does, so be sure to research common nutrient-related issues before assuming yellowing leaves are an indication of dehydration.

Keep in mind, water can also affect the soil’s pH levels, so it’s important to test the soil if your plants are responding poorly post-watering. Outdoor growers are advised to water early in the morning when the temperature is low (before the sun rises) to ensure the water is absorbed by the soil before evaporating into the warm daytime air.

Give Your Cannabis Plants Room to Breathe

Giving your marijuana plants enough room to branch out and get the carbon dioxide they need is as vital to the growing process as all those other aspects. Opinions vary on how far apart plants should be spaced from each other for adequate air flow, but most experienced growers recommend leaving at least three feet of space between each seed when planting in the ground. If you’re using pots or planters, keep them spaced approximately a foot apart once the plants begin branching out laterally.

In a Nutshell

All this information may seem like a lot to remember, but growing cannabis really isn’t overly complicated. For the most part, it’s simply a matter of paying attention to the soil prior to planting as well as throughout the growing process and keeping an eye on your plants while they grow.

If your marijuana plants have the right amounts of light, heat, air, water and nutrients, you can expect to produce some hefty yields! Every bit of time and effort you put into cultivating cannabis contributes to a bountiful harvest. Ready to get started? Visit to see our selection of cannabis seeds.