Basic Hydroponics

The term "Hydroponics" is fairly familiar nowadays, and is often explained simply as growing plants in water instead of soil. In traditional farming and home growing, the soil fills a number of functions. It provides stability for the plant, stores nutrients, retains water, and traps pockets of air that the roots need. In hydroponics a liquid fertiliser provides the water and nutrients. Often an inert material (such as clay balls) is still used to provide stability for the roots and to store liquid between watering - but it isn't a necessity.

Any future space colonies are probably more likely to use aeroponics - where the plant roots sit in a fine mist - or aquaponics - where the plants are part of a self-sustaining system that includes fish. However, hydroponics is a nice, simple introduction to the principle, and one with lots of opportunity for experimentation.

There are a number of quite different hydroponics systems, which vary in how water is delivered to the roots. Descriptions of the five main systems is available on the Simply Hydroponics website, but what is missing is the most basic system of all - hand-watering. This is the most like traditional house plants; you'll just water the plants when they need it.

Before You Start

Gather your growing medium and hydroponic feed. If you are watering by hand, then you don't want to be doing it every 15 minutes; and so we need a growing medium that is going to hold on to the water. Coco Coir is an excellent choice in this case - which is basically just the hairy bits from the outside of coconuts. As mentioned before, it does not contain any nutrients itself, but in all other respects it is similar to soil (it's brown etc.).

The choice of liquid nutrient can be more complicated. I went with ATA Coco Max A+B, mainly because it is specifically for use with Coco Coir. It is a two-part feed (comes in two bottles: A and B), which you mix together in water. I got some useful advice from the owner of a local hydroponics shop, and it can't hurt for you to consult an expert.

Mix up some feed before you start to save time later.

Step 1

Start by choosing your plants. It is entirely possible to grow from seed using hydroponics, but it would take weeks to realise if anything had gone wrong. With already growing plants, you can see the warning signs of any failed attempts more quickly. I'm using a pair of 1 year old orange trees. The misshapen leaves on the taller one are from a previous period of draught (where I forgot to water them).

Orange plants growing in soil, in pots Orange plants growing in soil

Step 2

The next step is to remove the soil. This step is slightly easier if the soil has been allowed to dry out a little - but not so much that the plant is showing signs of wilting. Spread-out some newspaper, gently squeeze the pot a few times to loosen the soil, and then coax out the plant. Gently (that word will be used a lot at this point) tease out the roots, and try to remove as much soil as possible. Finish by giving the roots a gentle wash. A little bit of remaining soil is OK.

Roots with soil removed Roots with most of the soil removed

Step 3

Now it is just like re-potting any plant; although in this case it is probably better not to add any stones at the bottom for drainage. Place some of the Coconut Husk at the bottom of the pot. Place your plant in the pot, and continue adding Coconut Husk around it for support. Press it in with your hands to ensure the plant is well supported. Finally pour in plenty of liquid feed until the whole growing medium is damp.

Plants in pots next to bottle of feed The final result


That's it - hydroponics at its simplest. You will just need to water the plants occasionally using the prepared growing medium. It is simplest if you make up a batch of the feed and store it in a bottle until needed. Just be sure to keep the bottle out of sunlight (e.g. in a cupboard, or thick bag), to prevent things growing in it.

Now obviously such a simple system is not going to give you maximised results, but it is a starting point. You could add a pump and a timer to automate the watering, add growing lamps, heaters, even place the plants in a tent and pump in carbon dioxide. All of the things that you might consider part of the futuristic technology of hydroponics. But just remember, at its simplest, it's just nutrients in water.


One month on, and both plants are growing well. If this is your first attempt, then so long as they don't die you can consider it a success.

Both plants one month after re-potting. Both plants one month after re-potting.