We love watercress – the peppery bite goes really nicely in warm winter salads and is particularly good at cutting through fatty meats.
The plant is very high in calcium, iron and vitamin C. It can grow wild in the UK but it’s really too risky to forage because of the possibility it’ll be contaminated with liver fluke.
So let’s grow some then. It’s a good candidate for a first hydroponic crop as it’s so easy to grow.
Watercress loves flowing water so I thought I’d build a cascade of pools for it. A hydroponic watercress setup like this could also easily be built on a smaller scale and is ideal for a patio – you don’t have to go quite as mad as this! On the other hand, this would scale quite well for a larger setup.
Ok so here are the materials we used:
- 1 x 90L reservoir tank – a black tank will minimise algal growth though you can still expect some
- 3 x tote boxes – we bought food grade plastic for these
- 6 x plastic “mushroom” trays or similar
- 3 x Speedfit tank connectors, 22mm
- 3 x 22mm Speedfit elbows
- 6 x 22mm Speedfit inserts
- 1 or 2m of 22mm Speedfit pipe
- 1 x Hailea HX-2500 650lph Adjustable Pump with Air Pipe
- 1 or 2m silicone tube for water
- Assorted wood offcuts to support everything
This is what I did
- Drilled a hole suitable for the tank connector – you can see I had to take a part of the lip away to get this as high as I wanted.
- Then it was JG Speedfit pipe to the rescue once again to join on the elbows.
- On the lowest one, I made the pipe down a little longer. This goes back into the reservoir but should still allow the water to splash in.
- This will provide plenty of oxygenation of the water so I didn’t really need the pump to have an air pipe on it and could have bought a simpler one.
We bring the watercress seed on in grow cubes and in a propagator in winter. These then slot quite well into holes snipped out of the bottom of the mushroom trays. The cubes should be about half way into the water. As it turned out we don’t really need 4 holes cut in each one as watercress grows really quickly!
Once it starts going you have to keep harvesting it to stop it flowering – give it a good “haircut” every so often and it’ll grow back really quickly!
We do put some nutrients in the water but have also run it with clean water and it seems to do ok. Water ph should be 6.5 to 6.8 The EC should be 0.4 to 1.8 (EC or Electrical Conductivity is a measure of the dissolved salts or nutrients in the water – I’ll go into this more in a later blog focusing more on hydroponics). Not enough nutrients or too hot a temperature and the watercress will bolt and start flowering so good to keep an eye on this.
Every so often you’ll have to start over again as things get clogged up and overgrown. Recently we’ve just started using some of the existing plants to do this rather than start from seed again. On the junctions of the stalks you’ll notice the watercress will start roots. If you just pop these into the water the plant will regrow quite quickly.
We usually run this hydroponic system in rotation, cleaning out one of the totes at a time and re-seeding it before doing the next one a couple of weeks later. You shouldn’t run out of watercress!
Oh and if you’re got too much and have some chickens – they love it!!
For more information on the health benefits of watercress or more information in general try www.thewatercresscompany.com/health-benefits
Suppliers for the various bits that went into this include:
GroWell Hydroponics www.growell.co.uk
Booker Wholesale www.booker.co.uk
Amazon UK www.amazon.co.uk
Nisbets Catering Supplies www.nisbets.co.uk
CN seeds cnseeds.co.uk
Just to clarify, we’re not directly endorsing any of these companies and we get nothing from them for mentioning them. They’ve just proven themselves to us to be efficient and reliable suppliers – 5 stars to all of them, We’ll continue to try and give you a head start by doing this throughout this blog as half the difficulty is trying to find out where to get the things you need to make something yourself
We’re running the pump off solar now which feels good. Our solar panels charge up a leisure battery in about 4 hours (on a good day!) and this runs the pump via a small inverter for about 3 days. When the battery get’s down to 40% capacity I swap it for another one.
Get an Arduino to monitor the battery capacity and tell us when to change the battery – this will save us checking the batteries every morning when we’ve got better things to do. Make the tech work for us!