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Case Study: Raised Bed Garden
   

First the standpipe

This garden is an example of how to install drip irrigation in a garden with raised beds. In this case, the owner wanted a drip system with a long service life and chose heavywall dripline. She also asked that the dripline in each bed could be easily moved out of the way for tilling in spring and fall.

A garden hose was used to deliver water to a standpipe we built and fastened to a garden wall post. The standpipe has a digital timer, an FLR4 filter, a PR2 pressure regulator and an FC16 adapter to join to T2 tubing.

Using a series of FB8 Barbed Elbows and FB5 Tees, we began extending T2 tubing to all the beds. The tubing had to cross the garden paths repeatedly to reach all the beds so we moved the wood chips that covered the paths to place the T2 tubing as close to the ground as possible.

Later the owner will come back and cover all the tubing in the paths with wood chips so that no one trips over the tubing and so that it is protected from foot traffic.

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The standpipe was fastened to the
garden wall post with metal clamps

   

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Narrow beds only required one length of D4100 dripline that was later notched into the wooden cross pieces

Narrow beds

There are narrow raised beds on the perimeter of the garden, so the first step was to join DL4100 heavywall dripline to the T2 tubing coming from the standpipe using an FB8 Elbow. We extended DL4 dripline around the entire permeter using FB8 Elbows to make the turn in each corner.

The DL4100 dripline has drippers pre-built inside the tubing that each deliver .5 gallons per hour and are spaced 12 inches apart.

The soil in the garden is a clay loam mixed with lots of organic material, ideal for good capillary action by the water from each dripper. One length of dripline should ensure a continuous wetting of the narrow beds.

The owner can test the system by operating the drip system for about an hour then digging down in the bed with a shovel to see the wetting pattern and how deep and wide the water is reaching. There may be only a small wet spot showing on the surface at each dripper but the water will wet a larger volume of soil beneath the surface, up to 24" in diameter or more.

 

   

Wide beds

The easy way to extend the T2 supply tubing to each bed is to keep as close to the side of a raised bed as possible to avoid having the tubing under foot. Then we used FB5 Tees and FB8 Elbows along with short sections of T2 tubing to branch off the main supply tubing. The tubing is routed up and over the edge of each bed at one end. It extends across the end of the bed to form a header. Use OE3 Support Clamps to hold 1/2" tubing tight against the side of a raised bed.

The beds are four feet wide so the owner chose to install three lengths of DL4 dripline about 18" apart in each raised bed.

When she plants, she will locate seed or bedding plants on either side of each dripline and close to where each dripper is located.

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Four-foot wide raised beds were built around the centre of the garden and narrow beds are on the perimeter

   

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Tees and elbows were used to extend the T2 tubing up onto each bed to join to three driplines. All the tubing in the pathway will be covered.

Attach the dripline

The T2 header is cut to add FB5 Tees and join the sections of DL4 dripline that extend the length of the bed. An OE7 Figure Eight end stop closes off the end of each length of dripline. The OE7 can be easily opened to allow flushing the lines at the beginning and end of each season.

The header and dripline assembly can be swivelled over and out of the way to permit cultivation at the beginning and end of the season. Barbed elbow connections are water-tight but the tubing can still be pivoted around the elbow.

The DL4 dripline was difficult to uncoil from the roll due to the low temperature on installation day but as the weather warms, the dripline will relax and conform to the shape of the beds.

We used OE4 Shepherd Stakes to hold the tubing in place until the weather warmed.

We filled an old thermos full of boiling water and dipped the end of the tubing to warm it and make it easy to push the tubing over the ends of the barbed fittings we used. As soon as the tubing cools, it shrinks tight to the fitting and is very difficult to pull off with your bare hands.

The owner will flush the faucet assembly when the water is first turned on, join the tubing to the faucet assembly, open all ends of the dripline and flush the entire system. The end stops are closed and the drip system is clean and ready to use.

 

   
 
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