Step 2) Wetting the Root Zone

Ok, in this step we will discover how to properly cover and wet the root zones of your plants and trees. Not vertically like we did in the last step, but horizontally.

Remember, in the last step we figured out how many minutes it took to water your plants to the proper depth. Now we are talking width.

Why width? Because plants naturally send out roots to the drip line, or foliage line. The leaves and branches will naturally direct rain water away from the trunk towards the outside rim of foliage.

We want to place our emitters at about the same place to take advantage of the natural tendencies of the plant

Remember the illustration below? You can see how plant root structure stretch out from the trunks. We want to place emitters so the water wets as much of the root system as possible. We also want to encourage new plants to spread their roots out, as well.

You can also see how some larger plants will need more then one emitter, and trees can need numerous emitters to form health root growth.

In the drawing below, you can see a couple of examples of emitter placement as it relates to the canopy of plants and trees

The small canopy might be a small ground cover or accent plant like a Lantana or maybe Penstemon. One emitter wets a large amount of the root area.

However, when we move up to a larger plant, say a Sage or maybe Ruellia one emitter wets only a small part of the root area. At least two are needed.

You can see that even a small tree then can easily require eight or ten emitters to water the root area evenly.

Don't forget, as the plant or tree grows and spreads it's canopy, so do the roots. Your emitters will need to be moved out or new emitters added to evenly wet the root area and deliver enough water for the size of your plants.

Adding emitters to trees can be a real chore, especially if you're not experienced. I like to use the 5/8" drip tubing to loop around the tree and if you add an emitter every 2' to 2 1/2' you get a fairly even wet zone.

Here we have dug out a hole for a 15 gallon or 24" boxed tree. We have looped the tubing around the edge of the hole. the placement of the tubing is important because you must wet the root area that has been in the container, but also encourage the root to expand and anchor the tree. Right on the edge is perfect.

I like to use five 2 gallon per hour emitters on a 24"boxed tree. Four around the edge of the container and one on the base of the trunk.

You can use the smaller 1/4" tubing or "spaghetti" to fine tune the exact drip point where the water will enter the soil. Again, as this tree grows, you will need to move these emitters out and add a few more.

In this image you can see the emitter placed on the 5/8" tubing and the spaghetti leading up from it. The spaghetti tubing can be up to 10' long before you begin to lose volume.

Soil composition is important here also. The more dense or clay like your soil is the more the water will spread out as it percolates down to the roots. You may not need to add two emitters to medium sized plant because the water spreads out nicely. On the other hand, sandy soils usually require more emitters because the water doesn't spread much at all. It can run straight down with only a small wet spot on the surface.

We'll talk a little bit more about soils and also about irrigation timing on the next step.

Step 3) Cycle and Soak.

Landscape Irrigation without the Numbers – Step one.

Step 1) Discovering your watering rate:

Basically in step one, we want to figure out how many minutes it takes your system to wet the root zone of your plants.

First we need to let your yard or garden dry out a bit.

Then you will water it once for the normal amount of time.

Then you will measure the depth of the wetted area under your plants.

Let the soil in your yard or garden dry out for the regular interval between irrigation cycles, plus maybe one or two extra days. Watch your plants carefully. You may need to hand water certain plants, especially your pots and containerized plants that begin to stress.

When you are satisfied the ground is dry, or when many of your plants are beginning to wilt, turn your irrigation system back on manually for one cycle. Everything should get the normal drink of water. If your plants normally get 30 minutes, run it for 30 minutes. The best time to do this is early in the morning or just after the sun sets. Wait about an hour after the normal watering cycle is finished, then grab your soil probe. You are going to gently push it into the soil about 4” - 6” away from the drip emitter or bubbler of each plant. Remember, I said gently.

**** But first, a word of caution. ****

Every yard has utility lines, water, electric, phone, cable TV, natural gas and sewer. Add to that, landscape irrigation pipe and hoses, pool piping, landscape lighting, electrical for outdoor kitchen, patios, fountain pumps, drainage line, etc. Anytime you dig or push a soil probe into the ground, you should understand where these things are and take proper precautions not to hit any of them. There is a chance that you could make contact with an electrical line and receive a lethal electrical shock. Never use a hammer or anything to drive or pound your soil probe into the ground. Also make sure your probe is rounded or blunt on the tip. This way, if you do bump a drip line or pipe, your probe will probably slide off rather then puncture or cut the line.

Always call before you dig or excavate! Arizona Blue Stake will mark your utility lines in your yard for free.

The soil will be wet so the probe should push in easily. My wife can do this with one hand. If you have very little hand and arm strength, you might need to use two hands, but be careful. If the probe doesn’t go into the soil easily, don’t force it. You can move to the other side of the plant and try it, or move to another plant and try it again. I have been using soil probes for a very long time and I have never damaged anything. However, I use them very gently as if I expect I might hit a drip hose or pipe.

When the probe hits dry soil, it will be become harder to push it down. Don’t force it. You are measuring the depth of the wet soil only. Hold your finger, or mark your probe at ground level and then pull it out. This is the depth of the wet zone or soil reservoir your irrigation system has provided for your plant.

The 1, 2, 3 rule works well for mature plant root zones. Here in the desert, ground covers have a root zone about 1 foot deep. Shrubs feeder roots will usually run about 2 feet deep. Tree feeder roots usually run about 3 feet deep. Lawns should be watered to about 8”.

Adjust your timer till you have the right wetted depth for most of your plants. You don’t have to be perfect, just get close and write down your results. I usually make a simple drawing with the wetted depth for each plant along with the number of minutes used on the timer. This is very close to the amount of minutes you will use to irrigate each given zone or valve.

Don’t go out and buy a bunch or drip emitters and try to balance each plant just yet. In the next step we will talk about proper wetting of the entire root zone and balancing the water rate at each plant. You may need to change or add some emitters in this next step. That will be when you can go out and buy stuff.

Work through your watering depths and check back here for Step 2. Wetting the Root Zone.

Landscape Watering by the Numbers

Ok, it’s mid July and the Monsoons haven’t made much of an appearance yet. Recently we’ve had the hottest days of the year (so far) and some of your plants are probably looking a little sick. Many of us actually over-water this time of year because we worry about our plants out there suffering in this heat. So, in the spirit of hot air and since July is now Officially National Smart Irrigation Month, here is the beginning of a series on how to water your plants.

There are some pretty good guides and pamphlets out there that cover the subject very well.

This is the best pamphlet I’ve seen so far and you can download a PDF here.

The problem is these guides take time and to read and follow and we are all busy, right? Sometimes it’s just easier to add more time to the controller. And so this is how it happens that people get big water bills and many times sick plants from over watering.

Would you like a quick start guide? OK!

I have a fairly simple process that is part of a program I use on almost all of the properties where I manage the Landscape Irrigation. I have developed this process because everyone’s yard, garden and landscape is unique. Every yard is a micro-climate all its own. Plus the irrigation system is almost always different too. Sometimes they need some work, but I’ll cover that in another article.

However, the goal is almost always the same. We must deliver just enough water to wet the root area of the plant plus just a tiny bit of extra. Then to let the root zone dry a bit, then repeat. I’ll show you how to do that in your yard in three steps.

You will need a soil probe for this process. I think every gardener should have one. It doesn’t have to be spiffy. A very long screw driver or a piece of rebar with a point on one end works great. A three foot long soil probe is best, but a 24” probe can work. I use an old piece of rebar with a “T” welded to one end and grind stripes every 6”.

Here is a picture mine. It’s old and not real trendy.

You don’t need a “T” on the end. Rebar bent to an “L” on the end will also work great. I think almost any hardware store that sells rebar, sells shorter pieces and can bend an “L” on one end for you. Concrete installers use bent rebar all the time to brace concrete slabs. Very long screw drivers are cooler looking but they can be expensive.

**** A word of caution. ****

My soil probe is all metal. Yours doesn't have to be all metal. I have used all metal soil probes for many years without a problem. Used properly, they are about as safe as any other tool. However, there is a chance you or I could make contact with an electrical wire, conduit, irrigation line, sewer line, or water line that has been buried in your yard. There is a chance you could come into contact with a lethal amount of voltage. If you decide to use a soil probe of any kind, use it at your own risk. Never use a hammer or anything else to drive of force your soil probe into the ground.

In the next article, I will cover the proper use of a soil probe. Used properly, I believe they are about as safe as any other tool. There are some really cool soil probes on-line that range from $80. on up. There are a number with fiberglass shafts that should insulate you in the event you strike a high voltage line on your garden.

So go find one in the garage, build one or buy one and then come back for step one.

Over half of your water never reaches your house?

The EPA and water providers across the country have been studying our water use. Water shortages in small towns to large metropolitan areas have forced water providers to gather data about usage patterns so they can find solutions to our growing demand.

One standout in the data is that nationally about 30% of the water that passes through our water meters goes straight to our landscaping. AMWUA (Arizona Municipal Water Users Assoc.) publishes 60% for Arizona. Why is that important? Because the estimated residential landscape water use in this country is roughly 7 billion gallons of water per day. My guess is this makes landscape irrigation the largest single water user in the American household. That has the EPA's attention. Worse yet, the study also show that roughly half of that water is wasted. How?

1) Over watering. Believe it or not, automatic controllers are part of the problem.

2) Deficient system design and function. Some systems just need a tune-up, others were just designed poorly and some weren’t designed at all.

3) Large lawns. The number one water user in most landscapes.

4) Evaporation and run-off. Some experts believe that when you water during the heat of the day, 60% of the water simply evaporates. Watering during the heat of the day in the summer isn’t good for desert plants either.

5) Leaks. A leaking valve can run through hundreds of gallons a day for weeks before you notice it. Some very small leaks make a big impact when they leak 24-7.

Not to worry. I’m going to cover each of these items in a series of D.I.Y. articles over the next few weeks. Each article will cover the most common reasons I see for the above problems and a number solutions for each. I’ll tell you what to look for and how to fix the problem. If you don’t want to fix it yourself, at least you’ll understand the issue better. You’ll be better prepared to talk to your sprinkler pro and you might even be able to tell if he really is a pro.

I always advocate hiring an experienced irrigation professional to maintain your system. Landscape Maintenance people usually don’t have the experience or the training to keep your system running properly. Some of the better maintenance companies will have a dedicated irrigation staff. This is a much better choice.

Of course you can always call me. Landscape Irrigation is how I got started in this industry and I will always have a passion for it. I would love to come out and help you tune up your system, perform a system Audit or replace your system with a more efficient design and the latest in water wise equipment.

Saving water in your landscape

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