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A Macro Post on Micro-Irrigation

Mentioned in passing, er…sometime, that we completed the micro-irrigation in the backyard over this past weekend.  I had received two kits from family members as gifts, and since we lunched the backyard sprinkler system with the install of the pool a couple of years ago (and now have officially 4 hundredths of an acre under cultivation – not including all the flowers), we needed a better system than hand-watering.  About three weeks ago we broke out the kits and started poking around at the bits and pieces, experimenting with the various sprinkler and drip heads, basically figuring out what would work best for everything we had in place.

The point of micro-irrigation, by the way, is two-fold:  first, it uses far less water to irrigate directly at the roots of the plants than to spray water everywhere with a hose;  second, some plants are very susceptible to mildew/fungus, most of which are encouraged, to say the least, by wet foliage.  

The kits that are available bill themselves as specifically for “container gardening” or “vegetable gardens,” but the sad truth is none of them are exactly what you need.  They’re more sampler packs, containing a certain number of fittings and drip/sprinkler heads.  So unless you have a really small space (and don’t care if everything gets watered a different way), they can only be considered starting points.  

After trying everything in the packages, here’s what we ended up with (important note: Home Depot has a very fine selection of microirrigation supplies, a la carte, in their plumbing/pipe section)…

The main line from the hose bib has to be 1/2″.   (Take it from me, even for a small space, 1/4″ is not sufficient.)  So, you need the following to get started (examples are from dripdepot.com, an excellent place to get what HD doesn’t have/carry):

 

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The left is the irrigation system for the perimeter boxes.  It has an inline filter that’s somewhat larger than the inside-the-swivel adapter filter, but seriously, how much crap is getting into a hose that’s never removed?  So, we went with the much simpler rig on the far right hose for the patio boxes.  Yes, hose splitters are important – just never run them all at the same time – as you always will need a spray hose handy.  Or maybe that’s just us…

  • 1/2″ End Cap – This is to close off the end of the 1/2″ tubing to form a closed system.
  • 1/2″ Tubing Holder Stakes – these will hold your 1/2″ tubing flush to the ground (though I’d bury it in high foot-traffic areas, leaving it above ground where the 1/4″ tubing connects).

 

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These are the two main supply hoses we run, both have been buried (AND staked down underground) in all the walking areas.

  • 1/4″ Microtubing – This is what will run water from the 1/2″ tubing to your plants.
  • Microtube Stakes – These are used to hold the tubing and aim drip emitters exactly where you need them (ie. at the base of a plant).

 

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Microtube stake holding a flag dripper at the base of a melon.

 

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Just punch a hole in the 1/2″ line, and connect a 1/4″ line with dripper/sprayer using a barbed connector.  It pops right in the hole and, if done right, does not leak. If it does leak, big deal, it’ll only be a little bit.

  • 1/4″ Barbed Tee – These are also used to connect the 1/4″ tubing to the 1/2″ water supply line but in a slightly different fashion.

 

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We use these to add the dripper perpendicularly to one long line, as in the narrow boxes.

  • 1/4″ In-Line Shut Off Valve – Just what it says.   Honestly we only use two of these, before the sprayers under the lemon and lime trees, because those guys do not need water every day, only about once a week.  Deuced handy though.
  • Standard 1/4″ Punch – This is used to pop holes in the 1/2″ line to insert the 1/4″ barbed connectors.
  • Goof Plugs – For when you screw up with the Standard 1/4″ Punch and need to close the hole.  Work out your plan beforehand and you’ll need less of these.
  • 360 Degree Adjustable Dripper – This we call a spider, since the water flows out in that pattern.  It is a low-flow dripper, we use them mainly for our round pots.

 

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Used here, naturally not in a round pot, but to water all four of these watermelons at once.  The spray is low enough that it will be under the melon leaves when they get bigger.

  • 360 Degree Vortex Sprayer – LOVE this one, though Home Depot’s version is 0 to 20 GPH, which is a faster water flow, and better for the carrot beds in which we are using them.  We also use these temporarily where we have seeds direct-sown.

 

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Waters everything in a 3 foot radius.

  • Button Drippers – We use these with the microtube stakes to direct water precisely at the base of established plants.

 

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Button dripper and microtube stake at the base of a red bell pepper plant.

  • Flag Drippers – We use these also to deliver water directly to the base of plants, though they emit a small stream of water (speed depending on which GPH  you purchase) instead of a drip, so we use them where a higher water volume is required.

 

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First is delivering water to one of the climbing roses via 1/4″ tubing.  The second is punched directly into the 1/2″ line to water the oregano plant at the back of the cucumber box.

We also use several larger sprayers (picked up at Home Depot), this one to deliver water in a wide pattern around the fig tree and the two pumpkin hills on either side:
 

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And these for the tree and corn boxes:
 

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The last one can be adjusted via a knob on the side to increase/decrease the spray radius. 

It all may seem complicated (increased no doubt by my “explanation”) but it really isn’t.  The key to success is to lay out your plan on paper before doing anything at all, and make sure you don’t get overly ambitious and try and do too much…there is only so much space that can be supplied by a single 1/2″ line, and the water pressure decreases the more sprayers you add.  Home Depot has a handy little booklet they offer at no charge in their irrigation section, pick one up, read, then make your plan and buy your supplies. 

The savings – in both money and sheer time spent watering – make this a must-do for backyard gardeners.  What used to take me well over an hour – and jacked our water bill up by $30/month in the heavy growing season –  now takes about ten minutes per zone, and I expect similarly dramatic savings in the water bill next month.  So, get thee to irrigating!