Wednesday, September 16, 2009

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.

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