Water Supply for Your DIY Greenhouse

Supplying enough water for your DIY greenhouse is one of the main requirements for the optimal growth of your plants. If your greenhouse is very small and you have only a few plants to take care of, you can do it the old-fashioned way – carry a watering can from the house and water each plant individually. But, as your greenhouse grows and you have more plants, you will soon find out that you need a better and easier watering system. There will be days when you simply cannot manage to go two or three times a day to give all the water your plants need, and your plants will suffer.

Basic requirements for any type of greenhouse watering system is that it uses water efficiently, without waste, and that it provides sufficient quantity of water for each plant at regular intervals.

There are many different systems for automatic watering of plants in the greenhouse. Some of them require that your greenhouse has its own supply of water, and some require electricity to run pumps. There are still many simple systems that do not require any utilities.

If you plan on adding an automatic watering system to your greenhouse, plan the lay of water pipes before you pour your concrete foundation or lay down the greenhouse floor.

Greenhouse Capillary Matting

Capillary Mats are made of special water absorbing material. They are placed below each pot or tray and plants’ soil takes water by osmosis, when needed, until the soil is saturated. Although you can keep mats wet by hand, there are systems with a container attached to the garden benches that supply each mat with water. Make sure that the water reservoir is hanging below the soil level, so that the water does not flow constantly and does not over-water the mat and your plants.

For watering individual plants, you can use water spikes attached to a simple water bottle. The spike releases just enough water for the plant’s needs.

There are also many double-pot systems which draw water from an attached reservoir through a valve and a tube.

To see an example of (or purchase) capillary matting for single hanging plant baskets, click here. Please note this will open a separate window  for amazon.

Greenhouse Drip Irrigation Systems

Typical Drip Irrigation Connection


Drip irrigation systems are very popular with greenhouse gardeners, because it they are very efficient, easy to install and the save water by being easily adjustable. Water is comes to each pot or tray through a system of tubes and spikes or nozzles. The tubes can be laid on the soil level, all over the greenhouse, or you can hang them over the benches and plants. The overhead system uses gravity to provide water, and does not need any pump or electricity to run. Such systems use a container filled with water, sufficient for one pot, or large enough for the whole line of plants. All you need to do is to refill the container regularly.

Hose Connections & Vacuum Breakers

More sophisticated drip irrigation systems are attached to a garden hose or the house main line.  In that case, you have to make sure that the water does not back-flow from the greenhouse to the house water supply and pollute the house water with the remnants of fertilizers or pesticides that you distributed through the watering system in the greenhouse. Such back-flow can happen if the pressure in the water supply drops to a low level when the municipal water pumping system fails, a line breaks or a fire trucks pump from fire hydrants. A hose connection vacuum breaker is a simple device that, attached to your greenhouse hose or watering system, will prevent such back-flow from the greenhouse to the house water supply.

There are many examples of vacuum  breakers available for sale. Here are three examples (for sale through amazon) in case you are searching;

Example 1 – Garden Hose Vacuum Breaker

Example 2 – Garden Hose Vacuum Breaker

Example 3 – Garden Hose Vacuum Breaker

Greenhouse Water Use Calculation

Greenhouses are greedy water users, particularly if you are growing plants such as tomatoes, hydrangeas or similar. In time, you will know the water needs of each plant you grow. Your water bill will show you how much water you used, and in some parts of the world it can be very expensive.  You can use a simple calculation to figure out in advance how much water you will need.

Bedding plants and pot plants need about half a gallon of water per square foot per day. To find out how much water the entire greenhouse uses, calculate the square footage of your greenhouse (for example 12’x16’) and multiply it by 0.5, for the average water use per plant. Most greenhouses have between 70 and 90 percents of usable space, so multiply the result you got by 70 or 90/100 and you will get a rough figure of your water use per day. For more precise calculation for different types of plants, check the Texas University calculator at http://aggie-horticulture.tamu.edu/ellisonchair/water/B1274.pdf . This article has some other useful and interesting advice on conservation of water and the protection of the environment from the greenhouse water outflow contaminated with fertilizers and insecticides.

Water conservation is becoming an important issue in many parts of the world. It is everyone’s duty as responsible greenhouse gardeners to use available systems and devices to provide optimal water for our DIY greenhouse, without wasting it and without polluting the environment.


Resource: http://www.irrigationtutorials.com/dripguide.htm

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