Set Up a Garden Irrigation System

On your sketch, note which plants need little water, either because they tolerate drought or are too young to have established root systems. Also note plants that need more water, such as plants that love water as well as established shrubs and small trees (under 15 feet). Large trees aren't good candidates for a drip garden irrigation system because their roots are so extensive — fortunately, established trees seldom need watering.

The emitters that slowly drip water to plants vary in how many gallons of water they deliver per hour (gph). For perennials, 0.5 gph emitters are usually large enough, placed near the base of the plant. For small shrubs, place one or two 1 gph emitters about a foot from the base. It's okay to estimate; you can add more emitters later if needed, or plug emitter holes with goof plugs if you have too many.

Once you know how many emitters you'll include, add the total gph for the garden irrigation line. If 250 gph or less, buy 1/2-inch tubing. For greater than 250 gph, get 3/4 inch.

 

The header attaches to the hose bib (or PVC pipe in the garden) and controls the water. Assemble the garden irrigation system in this order, starting at the hose bib:

1. Y-connector (optional). In essence, it makes two faucets out of one: a side for the drip system and the other as a regular faucet. Levers let you close a side.

2. Timer (optional) to turn the system on and off automatically.

3. Anti-siphon device to keep contaminated water from flowing into the house. See if your water utility or city requires a specific type.

4. Filter, to keep grit from clogging the emitters. It's easier to attach a Y-filter or T-filter than an in-line one. The mesh size depends on how clean your water is; typical municipal water can use 50 or 100 mesh.

5. Pressure regulator to adjust the household water pressure to a safe level for the drip system.

6. Adapter to connect the regulator to the drip line; get the same size as your tubing.

Lay the polyethylene irrigation tubing in the sun for a few hours to make it more pliable. Rake mulch out of the way and then lay out the main line. Cut the line at each lateral branch and reconnect the newly cut ends with a T-shaped compression fitting. Insert the lateral into the stem of the T.

After you lay out the main line and laterals, use a special punch to create holes for the emitters and 1/4-inch tubing. Then push the emitters and tubing into the holes. If you make a mistake, plug the hole with a goof plug. Put an emitter at the ends of the 1/4-inch tubing, to keep it from clogging.

Connect one end of the tubing to the header assembly. Turn on the water to make sure the water flows through all the main and lateral tubing. Turn off the water and cap the open ends of the main line and laterals so they don't gush water. Then turn the water back on and check that all the emitters drip.

Adjust the position of the tubing in the garden irrigation system, if needed, and then use special U-shaped pins to anchor the tubing to the soil. Rake the mulch back into place over the tubing; covering the tubing not only keeps water from evaporating, it protects the tubing from destructive ultra-violet light.