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Soil or Hydro?
by Nebula Haze
Which growing medium is right for your cannabis grow? Should you grow hydro, with soil, or a hydro-soil fusion (such as soilless potting mixes)? Which grow medium will produce the results you want?
Today, get a basic explanation of what to expect for each type of cannabis grow medium (including pros/cons, effect on yields, quality, etc)
Table of Contents
- Hydro Pros vs Cons
- Different Types of Hydroponics
· DWC (Deep Water Culture)
· Top-Fed DWC (Bubbleponics)
· NFT (Nutrient Film Technique)
· Ebb & Flow (Flood & Drain)
· Aquaponics (Fish for Nutrients)
· Aeroponics (Misted Air)
· Drip System (Automatic Watering)
· Hand-Watered Hydro (Soil-Hydro Fusion) - Some Hydro Systems Are NOT Suited to Cannabis
- Hydro Setup
- Hydro Maintenance
Soil-Hydro Fusion - coco coir & other soilless mediums
Intro to Growing Cannabis in Soil
Growing plants in soil seems to be what many people try first when it comes to growing in cannabis. If you’ve grown other plants in soil and/or have maintained a soil garden, this may be the best choice for you because you will already be familiar with a lot of what you need to understand to grow cannabis in soil.
Note: Do not use “Miracle-Gro” soil or any soil that has “extended release” nutrients. These types of soil will continue to release nitrogen to your plant roots for up to 6 months. This can burn your cannabis plants in the flowering/budding stage and reduce your overall yields.
Soil Pros for Growing Cannabis
Many Already Have Soil Experience - Growing cannabis in soil is similar to growing plants like tomatoes or corn - soil growing may be the most intuitive option for you, especially if you already have gardening experience.
Simple - hand-water your plants in containers
Outdoor Growing - most outdoor growers choose to grow with soil. In the wild, cannabis grows in soil, so growing outdoors in soil is most like a cannabis plant's natural environment. Many people find that when growing cannabis outdoors, soil is the simplest and most intuitive way to grow. Growing with composted "super soil" gives the grower the ability to grow outside without needing to add synthetic bottled nutrients or manage the pH of the soil.
Option 1: Store-Bought Soil + Nutrients - Growers can buy soil online or at a store, and simply add nutrients throughout their grow while watering for thriving, happy cannabis plants.
Option 2: Compost Your Own Super Soil - For those who don’t want to worry about soil pH or adding nutrients throughout the grow, there is the option of amending and composting your own super soil specifically made for cannabis plants. While this option takes more time before you start growing, it can be somewhat simpler especially for those who have composted soil in the past. Note: Some growers believe growing in organic composted super soil with a rich microbial life actually improves the taste and smell of cannabis by causing plant to produce higher levels of terpenes and terpenoids.
Soil Cons for Growing Cannabis
Pests - Soil is organic material, and there are many types of bugs that can live in soil. Often, soil-growers seem to suffer more often from pests attacking their plants than hydroponic growers.
Slower Growth - Growing in soil is not as fast as growing in a soilless or hydroponic setup - hydroponic plants tend to get better growth rates, especially in the vegetative stage.
Setup Cost - Basically you just need soil and a container. Common cannabis soil mixes include Fox Farms Happy Frog and Fox Farms Ocean Forest. Any high quality organic soil mix will do in a pinch. Avoid Miracle-Gro soil or anything with “extended release” nutrients! If soil seems heavy, it can be beneficial to add 30% perlite and 10% vermiculite to aerate and loosen soil. One proven soil option is to compost your own super soil, which can be made organically and gets some of the best results of any soil. Common cannabis containers include classic plastic pots, terra cotta pots, smart pots (fabric pots) and air-pots. Standard gardening pots do best with soil that has perlite added so that there’s plenty of aeration for the cannabis roots. Smart pots and air-pots each add extra air to the root zones from the sides, so they don't require much (if any) extra aeration or perlite in soil mixes.
Setup Effort - Soil growing probably has the least setup effort of any method (with the possible exception of growing cannabis in a soilless mix). The biggest effort will likely be choosing your soil and nutrients.
Learn the basics of growing cannabis
Maintenance Cost - After setup, the main cost of soil growing will be replacing your soil every grow (highly recommended - reused soil often does not get great results unless you know how to amend it with the nutrients that were used during your grow). Occasionally you will have to replaced used containers that crack or break.
Maintenance Effort - Watering your plants, providing cannabis nutrients as needed, managing the pH of your root zone (you should be managing your root pH if you’re not growing in composted super soil which has microorganisms in your soil to help manage pH and make nutrients available to your plant roots).
How long until harvest? Soil has relatively slower growth rates than hydroponic methods, but a tuned-in soil grow can achieve impressive growth rates if given a great environment and plenty of bright light. Most soil grows will require 1-3 months of vegetative time (depending on how big you want your plants) plus 2-3 months of flowering/budding (depending on your strain). Learn more about how long it takes to grow cannabis here. Some growers feel that cannabis grown in organic super soil has the best smell/taste profile, though this is highly disputed among hydroponic growers. :)
How long can grower be away? It’s important for a grower to always remain close by for their first grow, especially for inexperienced growers. Experienced growers can safely spend more time away from the garden. Bigger containers hold more water and therefore give growers more time away, since constant watering isn’t needed. In the best case scenario it is always best to check on your plants at least once a day. You never know when a pest infestation will take hold, a plant will fall over, or some other unexpected event will happen.
Growing with Hydroponics
Intro to Hydroponics for Cannabis
While technically any growing medium besides soil is considered hydroponics (including growing in a soilless medium like coco coir), when most people think of “hydroponics” they think of a water reservoir.
Technically any type of hydroponics with no inert medium is called a “solution culture” to differentiate it from other types of hydroponics.
This section focuses on types of hydroponics where the cannabis roots grow directly in water and/or the grower needs to maintain a water reservoir.
In the next section we will cover soilless mediums, which are technically a type of hydroponics, but which most people consider more like growing in soil.
Click Here for Short Summary of Hydroponics History
Hydro Pros for Growing Cannabis
Faster Growth - Faster vegetative growth than any other growing method, which can result in harvests that come in sooner.
Bigger Yields - Experienced hydroponic growers usually get bigger yields than experienced soil growers - given the same conditions (light, nutrients, etc).
Less Likely To Get Pests - Of all the grow types, hydroponic growers are least likely have their garden attacked by bugs or pests (though it’s definitely still possible). Many pests need soil as part of their lifecycle, and many growers accidentally introduce pests into their grow room when buying new soil.
Some Options Are Low Maintenance - Some hydro methods are relatively low maintenance, and many growers believe some options are as simple as growing in soil (learn more about different types of hydroponic setups below).
Hydro Cons for Growing Cannabis
Setup Cost - Hydroponic setups are usually more expensive to set up initially, and some types of hydroponic growing may require some DIY.
Figuring Out Nutrients - Getting the nutrients “dialed in” can be difficult for some hydro growers (especially when combining nutrients and supplements from many different companies) unless you follow a proven formula. In hydro, growers have total control over nutrients, which means hydro growers can fix nutrient problems quickly, but also that nutrient problems should be monitored and fixed as soon as possible.
Root Problems - Many unprepared hydro growers run into problems at the roots, though it’s important to remember that there are several proven steps that can be taken to ensure happy, healthy roots - such as providing plenty of oxygen at the roots and keeping water temps around 70°F (20°C).
Some Options Are High Maintenance - Some hydro growing methods are relatively high maintenance, and may take lots of checking in for the best growth rates
Growing Hydro Outdoors Can Be Difficult - While hydroponic growing can be accomplished outdoors, many people find it difficult to control all the essential variables outdoors (sterile environment, controlling heat/cold, powering pumps, etc).
Different Types of Hydroponics
Learn which ones are and aren’t suited for growing cannabis
Good Hydro Methods For Growing Cannabis
DWC - roots in nutrient reservoir that is oxygenated by bubbling air through the water. There are lots of different variations of the DWC method.
Top-Fed DWC (Bubbleponics) - like DWC except water is also pumped to the roots via a top-feed - fastest growth of almost any hydro system
View tutorial on how to make a Top-Fed DWC hydroponic system for growing cannabis
Note: What’s “RDWC”? It stands for recirculating DWC, which involves many DWC units hooked together with pumps and a “controller” to make sure all the plants get what they need. Usually only used for very big grows with many DWC units - this method allows a grower to maintain many DWC reservoirs in one place, and have the water pumped to all the plants
NFT (Nutrient Film Technique) - roots in containers on a tilted surface (often PVC piping). A water pump drips water from a reservoir to the roots of the first plant, and a shallow stream of water flows down the ramp over the roots of all the plants, one at a time. At the end, the water is usually drained back into the main reservoir to be recirculated. It is called “NFT” or “nutrient film technique” because there is a film of nutrient water flowing over the roots at all times.
Flood & Drain (Ebb & Flow) - roots in container which is flooded with water and drained on a timer - get plenty of nutrient water to roots as well as oxygen.
Aquaponics - roots in reservoir that uses fish to provide nutrients - you manage the fish to make sure they provide the right kind of nutrients, and the plant roots help filter the water for the fish. This method can be used for growing cannabis, but is not well suited to growing a lot of cannabis plants and can be difficult to get everything working together properly (for example: choosing the right type of fish, managing nutrient levels for different cannabis life stages, making sure the fish thrive, dealing with fish disorders that can cause fish to die, etc).
Aeroponics - roots in misted air - this method gets more oxygen to roots than almost any other system. Can be difficult to get setup if you want to DIY (do it yourself) but there are lots of already-made aeroponics kits for growers interested in this style of hydroponics.
Drip system - Basically an automated watering system - can be used full hydro, with a soilless medium or even with soil. Plants are provided water via top-feed from a reservoir of water. There’s lots of variation on drip systems. For example, sometimes these systems are re-circulating, and sometimes the water is discarded after being dripped through the roots. Sometimes the water feed in on a timer, and sometimes the water flows constantly.
Soilless Mediums (Hand-Watered Hydro) - While growing with cannabis roots directly in a soilless medium like coco coir is technically considered hydroponics, I will go over it in the next section because as far as the grower is concerned, the experience of growing in soilless mediums is more like a fusion of soil and hydro compared to most other hydro techniques.
These Hydro Methods Are NOT Suitable For Growing Cannabis
Raft System - Only meant for small plants like lettuce, raft hydro systems keep plants on a "raft" floating in a nutrient reservoir.
No tiny hydro systems like ones made for growing herbs! These hydroponic systems are far too small for a plant like cannabis. They don't have enough room for roots, or enough light to get cannabis to properly produce buds in the flowering stage. Don't use an Aerogarden (Aerogrow)! It is a struggle to get cannabis to grow in one of these, and you will get a lot better results using almost anything else (never mind the fact that they're expensive).
Never Use an AeroGarden for Growing Cannabis!
Setup Cost - many hydroponic setups are very inexpensive, especially if growers are willing to DIY and build their systems from scratch. Most of the parts for hydroponic systems are readily available at the hardware store and usually aren't terribly expensive. The more complicated your system, generally the more it costs. So if you need lots of pumps, tubing and special pieces you may spend quite a bit to get everything. Luckily, these days there are many companies that sell kits with everything included, and often these kits are comparable in price to building everything yourself.
Setup Effort - When it comes to setup, you will benefit greatly from doing your homework. I highly recommend finding a grower with a proven setup already (a grower who has at least one grow journal showing a successful harvest), and copy them for your first grow. Many already-made hydroponic kits can be found online, and these are often easy to put together. Certain setups that use a timer usually take some tinkering to get everything to work the way you like (example Flood & Drain, certain Drip systems, etc). For aquaponics, the grower must also consider the time and effort it takes to set up a tank that can support fish.
Learn the basics of growing cannabis
Maintenance Cost - Once your grow is setup, the majority of your maintenance costs usually go towards your nutrients and your grow lights. Learn about hydroponic nutrients. Learn about different grow lights. However, you will need to replace tubing, pumps and air stones every few grows or as they wear out.
Maintenance Effort - Your first grow will likely take a lot of maintenance as you get a feel for how everything works together. As long as you do your research beforehand, you will avoid common growing hydro problems like root rot and figuring out your hydroponic nutrient schedule. The amount of long-term maintenance depends quite a bit on which hydro setup you choose. A dialed-in DWC setup with a relatively large reservoir can take as little as a half hour each week to maintain the reservoir. Most hydro setups are relatively low maintenance as long as the grower has grown in the setup before. Some hydroponic setups take inherently more maintenance, for example aquaponics (growing with fish) and aeroponics (growing in misted air - take a bit of maintenance to make sure spray nozzles are always working properly).
How long until harvest? All hydroponic grow styles generally achieve faster growth than growing in soil, especially when it comes to speed of vegetative growth. The fastest growth rates are achieved when roots have constant access to both nutrient water and lots of oxygen. That means that growers get the fastest cannabis growth by adding more bubbles and dissolved oxygen into their water, or exposed always-moist plant roots directly to air (like aeroponics). While vegetative growth is often faster with hydroponic setups, growing hydro does not reduce the time a plant needs in the flowering/budding stage - that’s determined mostly by genetics.
How long can grower be away? Depends on the setups. It’s important for a grower to always remain close by for their first grow, especially for inexperienced growers with DIY setups. You need to be there if there’s a leak, or something stops working properly. With safe & professional setups, experienced growers can safely spend more time away from the garden. Bigger water reservoirs (or bigger pots for soilless mediums - anything that holds more water at a time) give growers more time away, since constantly adding water isn’t needed. Highly tuned setups like aeroponics tend to need more constant checking in, while simple and direct setups like DWC can be left alone for quite a few days. In the best case scenario it is always best to check on your plants at least once a day. You never know when a bulb will go out, a plant will fall over, or some other unexpected event will happen.
Hand-Watered Hydro - Coco coir & other soilless mediums
Intro to Coco Coir & Other Soilless Potting Mixes
While technically any growing medium besides soil is considered “hydroponic”, growing in coco coir or other types of soilless mediums can feel a lot like growing in Soil.
Soilless Pros
Faster Growth - Soilless growing mediums tend to achieve faster vegetative growth than growing in soil.
Less Likely To Get Pests - Soilless growers are least likely have their garden attacked by bugs or pests, but it’s definitely still possible.
Easy - Hand-water your plants in containers, just like soil. Many growers believe that growing in a soilless medium requires about the same effort as growing in soil. If your soil setup involves feeding nutrients in the water, growing in a soilless medium will be nearly the same experience.
Soilless Cons
Not As Fast As Full Hydro - Growing in a soilless medium will get faster growth rates in soil, but cannabis plants will not grow as fast as a hydroponic medium that is able to get more oxygen to the roots.
Figuring Out Nutrients - Getting the nutrients “dialed in” can be difficult for some soilless growers (especially when combining nutrients and supplements from many different companies) unless you follow a proven cannabis nutrient formula for your specific growing medium.
Cost - Soilless potting mix and container. One of the more common soilless mixes used for cannabis is “coco coir” which is made from coconut husks. Usually a soilless mix contains many different inert components to achieve just the right amount of aeration and water holding properties. I don’t recommend making up your own soilless mixes until you have some experience as it’s easy to make a mix that either holds too much or not enough water.
One proven soilless mix is to hydrate coco coir bricks and add 30% perlite and 10% vermiculite to aerate and loosen the mix.
Common cannabis containers include classic plastic pots, terra cotta pots, smart pots (fabric pots) and air-pots.
Classic pots do best with a lighter soilless mix with plenty of aeration for the cannabis roots. Smart pots and air-pots allow for heavier mixes that hold more water, since each of these types of pots add extra air to the root zones from the sides (which adds more oxygen to encourage faster root growth, but also means potting mixes tend to dry out faster).
Setup Effort - Growing with a soilless mix has very little setup - just get the mix and your container. The biggest effort will likely be spent choosing your soilless mix and nutrients. Remember, a soilless mix is technically a hydroponic setup, so it’s important to get nutrients that are either specifically formulated for your mix, or formulated for hydroponic growing. Nutrients that are formulated for soil usually do not work well for growing in a soilless setup.
Learn the basics of growing cannabis
Cost - The main cost of soilless growing is replacing your potting mix every grow (highly recommended, reused potting mixes often contain a buildup of nutrient salts that are difficult to properly rinse out). Occasionally you will have to replaced used containers.
Maintenance Effort - Watering your plants, adding cannabis nutrients, managing the pH of your root zone (you should be managing your root pH if you’re not growing in a soilless mix in order to make sure nutrients are readily available to your plant roots).
How long until harvest? Soilless mixes has relatively faster growth rates than growing in soil, and a tuned-in soilless grow can achieve impressive growth rates when given a great environment and plenty of bright light.
How long can grower be away? It’s important for a grower to always remain close by for their first grow, especially for inexperienced growers. Experienced growers can safely spend more time away from the garden. Bigger containers hold more water and therefore give growers more time away, since constant watering isn’t needed. In the best case scenario it is always best to check on your plants at least once a day. You never know when a nutrient deficiency will take hold, a plant will fall over, or some other unexpected event will happen that needs your attention.
Learn how I grew my first plants in coco coir
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