How to Grow Weed in a Hydroponic System

With weed laws leaning in a more favourable way across the world, many smokers want to try their hand at growing their own. A good hydroponic system can help foster fast and sufficient growth in any kind of cannabis plant. Here we will help you choose a system that you’re comfortable with based on your financial situation and experience level.

What is hydroponics?

Hydroponics is, in short, growing plants without soil. Instead, hydroponic gardeners use a nutrient-rich water solution to give the plants what they need. This generally allows for more control over every variable and can be a far more efficient means of growing, with plants often growing faster and producing higher yields than traditional soil-based methods.

In a hydroponic garden, plants are grown in containers filled with an inert medium, such as clay pellets, Rockwool, or coconut coir, which supports the plant’s roots instead of soil. This allows the nutrient solution to circulate more freely as well as give the roots much-needed oxygen. The containers are then submerged in the water which provides all the necessary nutrients.

What are the advantages of hydroponics?

Hydroponics has several distinct advantages over traditional soil growing.

Increased yield: Since growers can monitor every single aspect of the plant’s growth, and correct any errors in real-time, hydroponics typically grow faster and produce higher yields compared to traditional soil-based methods.
Water conservation: In a world of dwindling resources, anything that cuts down on use is a win. Hydroponics—perhaps counter-intuitively—uses less water than soil growing. This is because the water can be recycled within the system instead of just flowing out through the soil.
Year-round growing: While this is more of an indoor vs outdoor thing, hydroponics allows for year-round growing, regardless of weather conditions or location. This is particularly valuable to those living in areas with shorter growing seasons or limited outdoor space.
Space efficiency: Hydroponics can be set up in smaller areas than soil grows. Additionally, they can be stacked to utilise vertical space, making them a great option for those with limited outdoor space or those looking to maximise their growing area.
Pest and disease control: Since hydroponic systems don’t use any soil, the odds of developing soil-borne pests and diseases are practically zero. This can help reduce the need for pesticides and other chemicals.
Higher quality product: The controlled environment of hydroponics ultimately leads to higher quality products, with consistent flavours, potency, and appearance.

Does hydroponics have any downsides?

As great as hydroponics is, there’s a reason why it’s not the only method that growers use. No system is perfect and hydro has a few downsides that are worth keeping in mind if you’re looking to get set up.

High up-front costs: Setting up a hydroponic garden isn’t cheap, especially if you opt for more advanced systems. In addition to the light and seeds, you need air pumps, water pumps, nutrient test kits, and all manner of little extras that can very quickly add up.
Technologically complex: Put a seed in dirt and it grows. That’s what they do. By removing soil from the equation, hydroponic systems are more complex and require more technical knowledge.
Risk of system failures: As mentioned earlier, there are a lot of moving parts in a hydroponics setup. The failure of any one of them could spell catastrophe. Running a hydroponic system means constantly putting out small fires as things break down and need replacing. Even a small problem can result in crop loss if not addressed quickly.
Nutrient management: Being in control is a double-edged sword. While hydroponics lets growers monitor every variable, it also means that managing all of those levels is a time-consuming and potentially complicated task. Too much or too little of nearly any nutrient can lead to plant health issues or reduced yields.
Limited plant variety: Not all plants are suitable for hydroponic systems, and some may not grow as well as they would in soil. Luckily, WeedSeedShop sells a wide variety of seeds that are perfect for indoor growers.

What kinds of hydroponics setups are there?

No two set-ups are identical but, overall, they can all be broken down into a few broad categories. Each has its own pros and cons and which is best for any individual will depend on several factors.

1. Ebb/flow hydroponic system

An ebb/flow (ebb-and-flow) hydroponic system is a setup that uses a water pump to periodically flood a tray containing several plants (each in its own container) for a set amount of time, usually a few minutes, before draining the excess water back into the reservoir. This cycle is repeated throughout the day to make sure that plants get all the nutrients and oxygen they need. It’s one of the more simple and beginner-friendly hydroponic systems and it can typically be set up using common materials like plastic containers and PVC pipes.

Pros of an ebb/flow system

Easy to set up and maintain
Suitable for a wide variety of plants
Can be used with a range of growing media
Allows for good aeration of plant roots
Can be automated with timers or sensors for easy operation

Cons of an ebb/flow system

Often prone to system failures, such as pump malfunctions or leaks
Requires more maintenance to get proper nutrient solution levels and pH
Tend to require frequent monitoring to ensure the flooding and draining cycles are functioning properly
Not be as efficient for large-scale growing compared to other systems

2. Top-feed hydroponic system

A top-feed hydroponic system is one that uses a pump to deliver nutrient-rich water directly to the plants from the top. The system works by pumping water from a reservoir through tubing to a drip emitter or sprayer, which delivers the solution to the top of the plants. This water is absorbed by the plant and the rest drains back into the reservoir, where it can be reused. This is either run constantly or in cycles throughout the day.

Pros of a top-feed system

Easy to set up and maintain
Gives easy access to plant roots for pruning or maintenance
Can be used with a range of growing media

Cons of a top-feed system

Requires frequent monitoring to ensure proper nutrient solution levels and pH
Requires additional equipment, such as drip emitters or sprayers
Can be prone to clogging or uneven watering

3. Deep water culture (DWC) hydroponic system

In a deep water culture (DWC) hydroponic system, plant roots are suspended in a nutrient-rich water solution. The system works by using a reservoir to hold the nutrient solution and an air pump and air stone to oxygenate the water. The plants are placed in net pots with their roots suspended in the water. Also in the reservoir, an air pump provides oxygen to the roots, while the nutrient solution provides all the necessary nutrients for plant growth. It’s a simple and low-maintenance hydroponic system that’s ideal for many growers.

Pros of a deep water culture system

Simple setup and low-maintenance setup
Provides good aeration to plant roots
Suitable for a wide range of plants

Cons of a deep water culture system

Requires additional equipment for aeration, such as air pumps and stones
Not always suitable for larger plants or those with extensive root systems
More difficult to access and maintain plant roots compared to top-feed systems

What do I need to get started with hydroponics?

Now that we know what we’re doing, how do we do it? Before starting any grow setup, it’s important to put together a full checklist of everything you’ll need. Never tell yourself that you’ll “get it when you need it.” By the time you notice it, it might already be too late.

Seeds

It seems obvious, but first and foremost, you need seeds. Sure, you can use those seeds you got in that bag from that guy at that party last summer, but starting with good genetics is key to a successful harvest. WeedSeedShop has loads of seeds in all varieties so you can get the perfect strain for your needs.

Space

The space that you have to work with will ultimately define most of the choices that you make in your setup. It’s important not to crowd your plants too close together but you also don’t want your hydroponics setup to be too expansive. How much space you’ll need will vary from plant to plant, but a general rule is that you want about 0.1-0.25 m² (1-2 ft²) per plant.

It’s vital to choose a hydroponic system and container size that will fit your plants’ full growth potential and to ensure that there’s enough space between plants for proper airflow and light penetration. It’s typically a good idea to look at the plant’s product page for recommended spacing requirements.

Reservoir

This is where you need to pick a system and commit to it. What type of reservoir you need will vary based on what type of system you’re going to be using.

Ebb/flow: Plastic storage containers or trays make perfectly fine reservoirs for small to medium-sized setups. For larger setups, food-grade storage totes or tanks are ideal as they’re more durable and can hold larger volumes of water.
Top-feed: A plastic container or bucket with a lid is really all you need as a reservoir for smaller setups. For larger grows a food-grade tank is, again, recommended.
DWC: Similar to top-feed, a bucket with a hole in the lid is enough to get started.

Overall, it’s necessary to pick a reservoir that’s big enough to hold all the water you’ll need for the plants being grown in the grow area. Generally, a single reservoir is plenty as long as it can be easily connected to all of your sites.

NOTE: Always make sure that your reservoirs and all tubes are completely opaque. Any light getting into the water will cause mould or algae growth and this can quickly destroy your entire harvest!

Medium

Once you’ve got your reservoir, it’s time to start filling it up. Generally, most growers tend to opt for one of the following:

Rockwool: One of the most popular choices, Rockwool is made from spun mineral fibres and provides excellent water retention and air circulation for plants.
Perlite: A lightweight and porous material that can improve drainage and aeration in hydroponic systems.
Coconut coir: Made from coconut husks, coconut coir is a renewable and eco-friendly option that provides excellent water retention and aeration.
Vermiculite: Similar to perlite, vermiculite is a lightweight and porous material that can help improve drainage and aeration.
Clay pellets: Also known as hydroton or LECA, expanded clay pellets are lightweight, pH-neutral, and provide excellent drainage and aeration.
Gravel or pebbles: Most commonly used in ebb-and-flow hydroponic systems, as they provide support and drainage for the plants.

No matter which medium you choose, the process is effectively identical. Fill a net cup about halfway with your chosen medium, then place your seedling (in a sponge) into the cup and fill the space around it.

NOTE: What kind of cup you choose depends on your medium. You don’t want bits of perlite or coir clogging up your pumps. Always make sure that your medium is secure and wont fall through your cups.

It’s important that the plant’s roots are completely covered and not open and exposed to any light or immediate air. While they do need oxygen, exposing roots to the atmosphere is likely to cause algae or mould growth.

Nutrients

Here’s where things start to get a little tricky. Many soils designed for growing already have nutrients in them. However, in hydroponics, everything must be added separately.

Most companies sell some sort of three-part nutrient combo. This package should contain a mixture for the growth phase, the flowering phase, and a bottle of micronutrients. With hydroponics, it’s all about keeping things balanced. You’ll want to completely change your water at least every week and make sure that the nutrients stay fresh. As they get used by the plant, salts get left behind and these can kill a plant if left unchecked.

Light

The SINGLE most important item in any grow space is the light. Outdoor growers get to use free, unlimited solar power and there’s simply no way to replicate that indoors. However, the goal isn’t to grow 3-meter-tall trees, we want shorter, bushier plants and there are several great options available.

For most growers, the options come down to HPS or LED.

High-Pressure Sodium

HPS bulbs are the tried-and-true workhorse of hydroponic growing. With a strong red spectrum, their perfect for flowering and they are incredible at putting out massive amounts of light. HPS lights can be used in any kind of space and generally range from 200 watts (for a single plant in a small closet) to 1,000 watts (for up to 2×2 m).

With all of that light, though, they generate a great deal of heat that will need to be ventilated. They also aren’t incredibly efficient and running a 600-watt HPS light can get expensive.

LEDs

In the last decade or so, LED lights have fallen remarkably in price while increasing in efficacy. Today, the best LEDs are about twice as efficient as an HPS, offer a fuller spectrum of light, and emit virtually zero heat. Anyone looking to get started with indoor growing should really consider an up-front investment in a good LED light.

Ventilation

Yes, you need to ventilate your room. It doesn’t matter how many fans you have moving air around your grow space, you NEED old air taken out and fresh air brought in.

If you’re using an HPS light, venting heat out is crucial. Those things get very hot and will eventually burn your plants. But even if you’re using an LED, you need ventilation. Plants create a tremendous amount of moisture through transpiration (plant breathing) and that moisture needs to go somewhere.

Typically, your grow area should be between 20° and 28°C and have a humidity of 40% to 50%. If the area is too humid, mould and algae become very real risks.

How to add nutrients to a hydroponics setup

There are literally thousands of nutrient blends on the market that specialise in everything from root development to flavour enhancement. Most of these are optional add-ons that can be used to counter certain deficiencies or to boost certain aspects of a given strain. If you don’t know what you’re growing, or you’re starting a new set-up. Keep it simple.

Follow the instructions on the bottles. It really is just that easy. It can be tempting to go overboard and add in all of the boosters and additives but there is such a thing as nutrient burn.

Simply fill a watering can (10 litres is a good size) with cold water and pour in the recommended amounts of nutrients and give it a stir. Then, fill your reservoir. Remember, plant roots need some oxygen, so be sure to leave about a few centimetres between the bottom of the net cups and the top of the water level.

How to care for a hydroponics setup

Hydroponics requires a fairly close eye. Things can go very wrong very quickly (luckily, they can usually be fixed quickly, too). As they say, an ounce of prevention is worth a pound of cure, so keeping your grow area clean will save you hassle down the road.

Getting started

Make sure that you have everything you need on hand and ready to go before you ever even open your seeds. Too many times have growers (totally not me, I swear) germinated, transplanted, and then realised that their light still hadn’t arrived. Be prepared.

To get your space ready, get rid of any soft or permeable surfaces. Hydroponics uses a lot of water and anything like carpeting will become an issue as it will almost certainly begin to mould. Next, make sure that your walls are as reflective as possible. Matte white paint, mylar, and aluminium foil all make great choices.

Lastly, block off any external light sources. Plants need complete darkness to properly flower.

Cleaning

Before you start, clean everything. If it can be boiled or put through a dishwasher, do it. If it can’t, wiping it down with isopropyl alcohol is a great way to disinfect it. You’re building an environment specifically engineered to be ideal for plant growth. Any contamination will almost certainly cause problems down the road.

Once your plants have put down roots, cleaning your setup becomes increasingly difficult as plants in a hydro setup are much harder to move than those in soil. Every week, wipe down surfaces with isopropyl alcohol and make sure that the floor stays dry.

Watering

Change your water regularly. Pump it all out (or as much as you can at least) and refill your reservoir with clean water (no nutrients). Pump that out and repeat a few times until the water coming out of your reservoir is clear. Then, refill the reservoir with a nutrient/water solution. This will prevent the buildup of dissolved salts that can strangle your plant.

Want to know more? We’ve got a whole range of in-depth guides to cover all of your growing needs. Did we miss something in this guide? Let us know down in the comments.

How to Grow Weed in a Hydroponics Setup

What is hydroponics?