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Drip Irrigation: Learn the basics and benefits

Jul 6th, 2016 | Category: Growing

by David Pike

Last year’s growing season was so hot and dry I remember spending nearly an hour every morning dragging the hose around in my greenhouse to hand water each and every plant. With temperatures quickly climbing into the 90s, it was a challenge to patiently stand in the sun while I sprayed the base of each plant long enough to keep them alive for one more hot day.  I had plenty of time and incentive to dream about a drip irrigation system. This spring, as I was once again dragging a hose around my little tomato plants, trying not to crush them, and the greenhouse was heating up, I thought about how much time and sweat I could save this year if I actually installed that drip irrigation system I was dreaming of, so I finally did it!

Now, when I walk out to the greenhouse to water in the morning, I carry a cup of coffee with me.  I turn a valve on the hose, and hundreds of little drip emitters spring to life to deliver water at the base of each plant. I sit in the shade of a tree, sipping coffee and listening to the birds for about 15 minutes, and then turn the valve off – the greenhouse is watered! drip garden web 2

If you find yourself in a similar situation, with your garden, landscaping, greenhouse, or even the plants on your deck or patio, then you might consider a drip irrigation system as well. Drip irrigation companies advertise a 70 percent reduction in water usage, and because the water is being delivered to the base of your plants, you won’t be watering the weeds in between, resulting in less weeding.  They also claim it’s cheap and easy to install, but I’m not selling this stuff, so I will phrase this by stating that it’s relatively inexpensive, and not as difficult to install as you might think. These systems require a minor investment, and setting them up takes a little time and effort, but the long term savings in time, energy, and water is definitely worth it.

If you are still reading this, I will assume you are ready for a tutorial on setting up a basic system.  The first step is planning. Draw up a sketch of the area where you would like to install your system.  It doesn’t have to be exactly to scale, but if its close it will give you a better idea of the materials you will need. Draw in the house, buildings, paths, plants, trees, faucets, and any other features worth noting.  Next, take a look at your sketch and determine where the distribution hoses (1/2” plastic hoses) can run from a faucet to the area you are watering.  Distribution hoses can be up to 200’ long, and your plants can be up to 30’ away from the distribution hose and still get watered.   Now you will want to consider your soil’s drainage rate. Clay soil drains slowly, so it needs to be watered slowly and for a longer time than fast draining sandy soil. Use slower emitters in clay soil (1-2 gallons per hour), and faster emitters in sandy soil (2-4 gph). With your sketch in hand, walk outside and take notes about how many, and what type of emitters you will need for each plant. There are many types of emitters. There are sprinklers, flag drippers, soakers, stakes, and sprayers. They come in a variety of different flow rates, and some are adjustable. The easiest and most water efficient are flag drippers and soaker hoses, since they are not spraying water up into the air where it can evaporate. As a general guideline, for small plants, a 1 gph drip emitter is usually sufficient. Larger plants will need a 2 gph emitter, and very large shrubs will need 4 gph or multiple 2 gph, etc. Areas with lots of small plants, such as a lettuce patch, or a flower bed will small annuals, can be watered using 1/4” soaker hoses that plug into the distribution lines.drip lines web

Now that you have an idea of the layout of your system, you can head to the hardware store to buy materials. See the sidebar for a complete list of materials.

The anti-siphon, filter, and pressure regulator all attach in series to the faucet.  From there, attach a distribution hose and lay it out along its intended course.  This is easier said than done, because it comes in a tidy roll, and as it unspools it will corkscrew all over the place.  To make this easier, unroll it in the sun and as it warms it will soften.  Keep pulling on the end and twisting it as needed to work out all those pesky corkscrews.  Use stakes every 10’ or so to hold it in place, and put on an end cap.  When the distribution hose is set in place, use the hole punch tool to punch holes where you want to run a length of 1/4” hose to a plant.  Pop a barbed connector on the end of the 1/4” hose, and then pop that into the distribution hose.  Put an emitter on the end of the 1/4” hose and stake it about halfway between the base of the plant and it’s outermost leaves.  You can use up to 30’ of 1/4” hose to reach plants away from the distribution hose.

If this sounds complicated – it’s really not. Once you see the parts and play around with how they go together, you will figure it out quickly. It’s easy to fix mistakes, if you punch a hole where it shouldn’t be, just pop in a goof plug.  If you put in a wrong part, they pull out with a bit of prying.  All these hoses cut easily with a pair of garden shears.  If you would like to hide your system from view, you can dig a shallow trench to lay the hoses in, but don’t bury the emitters or they will clog.  If you plan on installing your system on a hill, be sure to use pressure compensating emitters, or the emitters at the bottom of the hill will have a much higher flow rate due to their higher pressure.

Materials Needed

Here is a list of materials you will need:

Anti-siphon – stops hose water from being siphoned back into the house.

Filter – keeps sediments from clogging the system.

Pressure regulator – lowers the water pressure down to 25 psi.

Hole punch – punches holes in distribution hose for 1/4” tubing.

Barbed connectors – to attach 1/4” tubing to distribution hose.

Stakes – keep the hoses in place.

Distribution hose – 1/2” hose, comes in rolls up to 50’.

1/4” hose – attaches to distribution hose to water nearby plants. 50’ rolls.

1/4” soaker hose – percolates water over an area.

Emitters – Drippers, sprayers, sprinklers, etc. attach on 1/4” hose.

Goof plugs – in case you punch a hole where it shouldn’t be.

End caps – cap ends of distribution hoses.

 

Optional:

Corner connectors – to turn a sharp corner.

“T” connectors – to divide a line into a “T”.

“Y” connector – to connect a regular garden hose on your faucet as well.

Timer – automates the entire system.

 

Published in the July 2016 issue of Grow Northwest 

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