Dish is Square Mile Farms’ Head Farmer. He’s spent the last year experimenting with growing 40+ types of vegetables, herbs and microgreens at our Paddington rooftop farm and in our office farm installations. Using his knowledge of building and maintaining indoor hydroponic systems he is on a mission to help London workers reconnect with their food by helping them grow it themselves!
Getting started with hydroponics
Are you interested in hydroponics or growing from home but don’t know where to start? Do you want to make your own system by up-cycling materials from your home? Growing hydroponically at home has lots of benefits: a regular supply of fresh, nutritious produce will certainly save you from making lots of trips to the supermarket!
There are a lot of different hydroponic systems, (check out my previous blog explaining them). In this blog we are going to cover the simplest one to understand. I’m going to explain how a Deep Water Culture hydroponic system works and how you can build one for yourself in no time at all.
What is the best hydroponic system for beginners?
Deep Water Culture (DWC) is the easiest type of hydroponic system that you can build and maintain at home. In this system, the plants grow with their roots submerged directly in nutrient-rich water. For home growers, this can be achieved by growing in large opaque storage containers or buckets. Commercial growers use rafts which float on a large bed of water; these work like a conveyor belt with young plants added on one side, they will move along until ready for harvest at the other side.
The lack of moving parts or recirculating water makes DWC systems relatively simple and cheap to build. The water in DWC systems does not recirculate, it remains sitting in the reservoir for the entire duration of the plant’s life. This means you must aerate the water to replenish oxygen that is used by the roots.
In soil, air pore spaces provide the much needed oxygen for roots and in recirculating hydroponic systems, water is aerated in the process of being pumped around. We can remedy this in a DWC system by using an air pump with an air stone attached (used in fish tanks) to ensure the water remains oxygen rich.
What can I grow in my DWC system?
The best crops to grow in DWC systems are Lettuce, Kale, Chard, Bok Choy, Basil and Parsley. These are all plants which are not too top-heavy. In DWC systems the roots are not well anchored and that means growing tall plants like tomatoes can be difficult, if you do grow them, you’ll need the right supports to keep the plant upright.
How to make a DWC hydroponic system at home
Materials: (scroll down for some product suggestions with links)
Storage container or bucket
Airpump with air stone
Hard Water Liquid Nutrients (A & B)
Hole saw with arbor
1. Find a suitable container for the system
Many find that deeper storage containers and buckets work well for these systems because the deeper the reservoir of water, the more stable the nutrient solution will be. Fluctuations in nutrient concentration and pH are more likely in smaller reservoirs, you will also have to top up the water more regularly.
Light should not be able to penetrate your container, otherwise there is a high risk that algae will grow in your water. I used this 55l opaque storage container which we had leftover from a previous project. In retrospect, I would have preferred to use a deeper container but for my purposes of growing leafy greens this will work fine.
2. Drill holes into the lid of the container
The plants will grow in net pots, these are pots with plenty of holes for roots to grow through. The next step is to drill holes into the lid of the container where the net pots will sit. This requires the only specialist tool you’ll need in this build, a hole saw, these are quite affordable and easy to use. The size of net pots you use must be larger than the hole so they don’t fall through.
If you’re using a wider container like mine, you can drill multiple holes. It’s important to plan carefully here: I kept the holes 15cm apart to accommodate for the size of the mature plants. If you’re using a 20l bucket, I advise drilling one hole in the centre to make a single plant system (they’re great for growing something larger like tomatoes or courgettes).
Pro-Tip: Place some wood below your lid when you drill your holes, this will prevent the saw jolting and breaking the plastic.
3. Assemble your air pump
The air pump must remain outside of the reservoir. It will come with a check valve, this ensures that the pump does not suck water back up if it is turned off. If it does not come with one, you must keep the pump above the water level.
Connect the air stone and check valve with a length of tubing, ensuring the arrow on the check valve faces the air stone. Then connect the check valve to the air pump in the same manner.
4. Fill the reservoir, add nutrients and adjust the pH