What is hydroponics?

Hydroponics is simply growing plants in water rather than soil. In order for the plants to grow well, we need to add all the necessary nutrients to the water so for the plants to use.

Why grow plants with hydroponics

There’s many reasons to grow with hydroponics, we go into more depth here, but a couple of good reasons include:

1. Faster growing plants - since we supply all the necessary nutrients to the plants roots, there’s no need for the plant to hunt around the soil for what they need so they can concentrate on growing quickly.

2. Less Care. Growing you plants in water eliminates one of the biggest challenges to home gardening, correct watering. You can’t over water or under water with hydroponics. So long as the roots are partly submerged your plants will be happy. Growing plants in soil particularly in pots is not so forgiving. Forget to water them on a hot day and your plants may die. With Hydroponics you can typically go a week or more without having to touch the water.

3. Less effort. Gardening in soil will often mean heavy work digging the ground over or weeding. There’s no need for a spade or a fork with hydroponics; and depending upon the system you choose to grow in, plants can more easily be grown off the ground and so eliminate the need to bend down.

Although with the right balance of nutrients it is possible to grow almost any plant, for most people it would be impractical to grow very large plants, for example fruit trees. Also when growing a large volume of slower growing plants, it may not be economical to use hydroponics.

What can I grow with Hydroponics

Well, almost anything. With a quick google you will find plenty of examples of plants you wouldn’t imagine would be suitable for hydroponics… potatoes? There are of course plants which are more commonly associated with hydroponics for example lettuce or salad greens. Lettuce are some of the easiest plants to grow with hydroponics. They grow quickly and importantly do not grow too large. Check out our Blog pages to see some of our lettuce trials.

Plant size is particularly important when growing indoors where additional lighting might be needed. It may not be possible / affordable to house large plants and provide them sufficient light. Try growing compact plants and crops like some of the chilli varieties we stock.

Now this isn’t an issue if you are intending to grow outdoors or in a greenhouse. With hydroponics you will quickly learn that there is no one size fits all approach. This variety can be some of the attraction to Hydroponics but to begin with there are some simple approaches.

Other ideas for plants to grow indoors include, strawberries, spinach, herbs, flowers, whilst outdoors or in greenhouses you could try tomatoes, cucumber, blueberries etc.

How to get started

Hydroponics can be as simple or as complicated as you want. The simplest approach just requires:

1. A bucket or tray (preferably a dark colour to exclude light and with a lid)

2. Something to hold your plants up e.g. a mesh pot and perlite

3. Some nutrients to feed your plants

4. A means of measuring Nutrient Concentration (EC Meter of rule of thumb) and measuring pH (pH pen or pH test paper)

5. A pipette

6. Light (the sun or artificial light e.g. a grow lamp)

Firstly you’re going to want to pick some seeds. Lettuce is a good place to start. They are simple to germinate and quick to grow.

Germinating your plants

Next you need to germinate your seeds. There are lots of different methods described on the internet. One method is to fill a mesh pot with perlite and then spread a few seeds on top. Lightly cover the seeds and then leave them standing in water (so the water comes half way up the mesh pot). This can be tap water, rain water, bottle water, distilled water. Any kind of clean water will do.

Within a few days your seeds will germinate and start to push its root (Radicle) down towards the water. After a few more days, the stem will start to grow followed by the seed leaves (Cotyledons). Once the seed leaves have opened it’s time to change the water for nutrients to start to feed your seedlings.

Growing your seedlings on

Replace your water with a hydroponics nutrient like Hydrofeed Complete. It must be a specific hydroponics nutrient that has all the elements your plants will require. A standard fertiliser will be missing many of the elements required because these would normally be provided from the soil. See below for how to mix nutrients.

Make sure that your seedlings are getting plenty of light. They’ll need up to 14 hours a day. You can either grow them outside in spring or summer or indoors any time of year (under an artificial light). Be careful trying to grow plants on a windowsill with modern glass as this will filter out the light your plants need.

At this point you may wish to move your plant into a pot or other system to grow it on. If you’ve grown your seedlings in a mesh pot, the simplest approach is to use a lidded container. Make sure the lidded container is deeper than the height of your mesh pot and won’t let the light in (transparent pots are therefore not ideal). Cut a round hole in the lid slightly smaller than the mesh pot diameter. This is so the mesh pot will hang from the lid. Fill the container with sufficient nutrient solution so that the mesh pot will be half submerged once the lid is replaced and the mesh pot inserted into the hole.

Mixing hydroponics nutrients

Follow the instructions on the hydroponics fertiliser and ensure that you have added sufficient fertiliser to reach a suitable concentration. Ideally this would be measured with an Electrical Conductivity pen but it would also be possible to follow a rule of thumb e.g. for Hydrofeed Complete, 10ml of fertiliser per litre of water (5ml of Part A and 5ml of Part B) will give you about 0.7-0.8 EC in addition to your water.

Water from your tap will have some mineral salts dissolved in it already. Soft water will have less than hard water. Your plants will be able to use some of these minerals but most of it will just get in the way of the good minerals your adding to it from your fertiliser. The water out of your tap will have an EC above 0. It could be as low as 0.2 or as high as 0.8. For example if your tap water has an EC of 0.4 and you add fertiliser to it until the reading is 1.2 then 0.8 of that will be due to the fertiliser. If your water is much harder e.g. an EC of 0.7 then that same amount of fertiliser added will give an EC of 1.5 for your nutrient solution.

If your area has extremely hard water (you can look this up on the internet) then you can always use another water source. Options include rain water (which has less mineral salts), the cheapest bottled water from the shops or you could use distilled water (this is the best option as you will then know exactly what’s in the nutrient solution you mix).

There are many types of hydroponics fertilisers on the market, some are for early phases of plant growth, others are for when your plants are flowering/fruiting. Some will come as a single part (but will not contain all the elements your plants will require). Most will be in two parts that must be added to your water separately so they don’t clump together. You can also get multi-part single fertilisers where you can balance the concentration of chemicals yourself. We recommend starting with a fertiliser like Hydrofeed Complete as it contains all the elements your plants will need and is easy to measure out.

Once you’ve added your fertiliser and made up the nutrient, the pH needs to be checked and if necessary adjusted to between 5.8 and 6.2. To do this you will need to have a way to measure the water pH (a pH meter or pH measuring strips). If the water is too acidic/ph is too low, then add a pH adjuster (PH+/PH Up). This is an alkali which will raise the pH. Similarly if the pH is too high i.e. too alkaline, then you will need to the opposite pH adjuster, an acid (PH-/PH Down). We recommend using Hydrofeed pH adjusters as they are less dangerous to handle than other common pH adjusters on the market and, particularly for smaller quantities of nutrient, are easier to use.

Maintaining your plants

Your plants will need some ongoing maintenance. Typically this will require some attention once a week certainly far less than other potted plants.

Your plants will be using water and so the water level in the container will reduce. This will have the effect of increasing the nutrient concentration. It’s important to ensure that there’s enough water and that it is of the right quality. It is possible to add more water but remember to check the EC and pH as this may change when you add more water. Adding water to your nutrient can help extend the life of the nutrient however your plant will be using up the elements in the nutrient solution, potentially at different rates. The EC may seem fine but it doesn’t necessarily mean that there is enough of every element in the nutrient solution. It is therefore better to refresh the nutrients regularly e.g. once a week.

If you are growing your plants outside then keep a watch for any pests. Just like any other gardening, pests will love your tasty plants. If you grow indoors this will be far less of an issue. In our experience, growing lettuce indoors under artificial lights means no bugs, which is great when it comes to harvest time.

Again if you are growing your plants outside, watch out for rain. It seems counter intuitive but rain can be bad. If the rain gets into your nutrient solution it will dilute it and change the pH. It is even possible that it will swamp your plants. So best to keep your plants under cover or stop the rain getting into the system.

As your plants grow they may need some additional support (particularly if they grow tall, like tomatoes). You will need to provide support where necessary and needs to be done every now and then.

Where can i grow plants with hydroponics?

Hydroponics opens up some more options for where gardeners can grow their plants. Just like plants growing in soil, you can grow plants with Hydroponics outside in the garden, on a balcony, in a greenhouse or poly-tunnel or indoors.

Using Hydroponics outdoors eliminates the need for good quality soil (or any soil at all), level ground, weed free ground etc. The systems used to grow can be lighter and hence easier to lift and hang on a wall or other vertical arrangement, making it great for space saving.

Using Hydroponics in greenhouses has all the benefits described above but also plants will suffer less water stress. It is possible to have automatic watering systems for soil based plants however this type of system is just as complex as a pumped hydroponics system but uses more water and typically won’t grow as quickly.

Plants can be grow with Hydroponics anywhere indoors using artificial lighting, even in the basement. This can also be done with plants in soil but is easier and cleaner to do with hydroponics and doesn’t bring bugs inside like it does when growing in soil.

Finally growing in spaces which are small, where mass might be an issue, such as balconies and rooftops, hydroponics offers approaches that would be lighter than when growing in soil.

Approaches to Hydroponics, why choose a different system?

The approach described above, sometimes called a Bato bucket, is the simplest way to grow plants with Hydroponics. There are many different setups that can be used. It is possible to add a fish tank oxygenator to the bucket which will keep the water aerated. This is more important with larger volumes of water as there will be less surface area for air to be absorbed.

Other more complex systems involve pumping the nutrients to the plants. These include:

• Nutrient Film Technique - This is where nutrient solution is pumped to the top of a network of pipes which allows the nutrient to flow over the roots of the plants you are growing. It requires more complex equipment but means that the roots receive the necessary nutrients and are never short of air. It is also a lighter weight system as it uses less water. The downsides however are temperature control of the nutrient is more challenging and if there is a long interruption in the power to the pump or a pump failure then your plants could die.

• Flood and Drain Technique - This is where the nutrient solution is pumped into a grow bed. The pump is on a timer so that nutrients are pumped for a set time. The grow bed is a tray or similar with a grow medium and some small holes in the bottom. The flow rate of the pump and the holes in the tray are sized so that when the pump is turned on for a short time, the grow bed will fill up. When the pump is turned off, the grow bed will slowly drain leaving the plant roots wet but not flooded. This way the plants regularly receive nutrients but also have plenty of access to air. As with the nutrient film technique it would be problematic if there is a long interruption in the power supply or if the pump failed.

• Deep Water Culture - This is very similar to the bucket technique except plants are often grown in rafts floated on the surface of the water. The water is then pumped around the system to ensure an even mix and that it is suitable aerated. This technique is good for growing large volumes of smaller plants and is less sensitive to temperature changes due to the larger volume of nutrient used.

• Drip Feed - This technique is where nutrient is slowly dripped onto the plants via a network of small pipes. The plants are grown in a container with a grow medium and the nutrient may be collected and pumped around the system again or is sometimes discarded. This technique is often used commercially to grow tomatoes.

• Aeroponics - This is a system that is similar to the drip feed system except instead of dripping the nutrient onto the plants, it is sprayed onto the roots. Plants grown this way will be supported such that the roots can be suspended in air rather than using a grow medium.

Depending upon what you plan to grow, what space you have available, whether you have a power supply and how much you wish to spend on the system will determine whether any of the approaches above are more suitable.

How do I dispose of hydroponics nutrients after they’ve been used?

Safe disposal of nutrients is important in order to protect the environment. It is important to ensure that any fertiliser is prevented from getting into the ground water and river systems as it will promote algae growth which will harm the river ecosystem. You can dispose of your fertilisers by recycling them on your flowerbed (rather than use a separate fertiliser). Just ensure that the pH is appropriate for the type of plant you are fertilising and that the concentration isn’t too high. If in doubt then water it down. Alternatively small quantities of fertiliser can be washed down the drain where it will be treated at a sewage plant.

For larger volumes e.g. for commercial growers, it is possible to filter the waste water to remove the nutrients and make it safe to dispose of the used water.