The first step in moving forward is to develop a working irrigation diagram on paper. Seriously, there are some folks who like to wing-it but this only means mistakes creep in and (if you’re anything like me) you’ll have to make multiple trips to the supply store or online ordering.
I’m going to demonstrate using our own garden as an example because I intend to install a system next year. I’m really tired of struggling against the heat with a shallow soil that dries out too fast and reduces both growth and survival rates. So what you see me doing is the real thing.
Plan Your Work And Then Work Your Plan.
Get some graph paper and measure/sketch out your garden.
Here’s my rough sketch of where I want to install drip irrigation in our gardens. Note I suggest you do it first with pencil because you’re going to want to change things up.
What’s a Zone?
This is a good time to introduce you to the concept of “zone”. A zone is an area of the garden that will receive irrigation. In a very small garden, it’s quite possible you’ll have one zone. But as your garden gets larger, multiple zones emerge.
Our island property will have more than this because we’re running larger gardens and they’re spread out more. As the diagram below shows, we’ll have six potential zones. One zone for each of the major garden areas. The fourth and fifth zones are for our trees. I intend to run drip emitters out to these large trees to eliminate any future heat/drought effects.
Note that I could easily combine the shrub bed and shade garden at the back of the house into one zone and in real life, I likely will. I separated them out for the purposes of this lesson series. The same thing for the front perennial gardens and the vegetable gardens. I can run them on a single zone as well.
Home gardens on urban lots may only need two zones. One for the front yard and one for the back. Our Florida garden has one for the east side and back and the other for the west side and front. But two zones is always a good idea.
Possible zones are circled in red.
Rules Of Thumb For Emitters and Drip Hoses
- Drip irrigation hoses tend to drip at 1 gallon per hour per foot of hose. So a 50-foot drip hose puts 50 gallons of water out every hour. That water will travel between 6-inches (15cm) to 12-inches (30cm) away from the hose.
- Emitters for home use are generally 1-gallon per hour per emitter.
How Big Is A Zone?
Here’s where you have to understand your flow rate. If your flow rate is 600 gallons per hour, then you can use 600 1-gallon per hour emitters at the same time or 600 feet of drip hose.
If your flow rate is 200 gallons per hour, you can use 200 1-gallon emitters at the same time.
If your flow rate is 200 gallons per hour, you can use four 50-foot lengths of drip hose (the kind that weeps along its entire length)
In our case, there’s a slight chance I’ll use up the flow rate for our pump in each zone as I expand the gardens or add more plants in each (more plants will demand more water)
Also, quite frankly, I have no idea what I’m going to use in the future so having extra zones won’t hurt us.
Given I’m not automating the zones (eliminating expensive electrical switches valves) having a few extra isn’t a concern. If I was going to automate it all, I’d try to be a little closer to “reality”.
But if you look closely, you’ll see the back shrub and shade garden could likely be combined into one zone and the front perennial and vegetable garden could be combined.
The two outlying tree areas are going to require their own system.
So, bottom line, I will likely install just four zones.
This is one advantage to drawing it all out. You get to visualize how close/far away from each other your garden zones will be.
A Point To Understand
This is the rough drawing. It’s identified the basic zones. BUT, your real zones will depend on your flow rate.
We now know where we want to irrigate and if there are specific plants we want to keep well watered.
But there are multiple ways to deliver the water – from micro-droppers and container drippers to big impact sprinklers and drip irrigation.
I’ll be using two kinds of emitters.
- Soaker hose irrigation for all the general garden beds.
- Drip emitters for specific trees. (I want to minimize the amount of watering systems around the trees to reduce the possibility of mower damage.) It also is more efficient to put emitters down for specific trees. They’re also more expandable as the tree grows.
Note the commonly available emitters usually work at 1-gallon / hour. Given the demands of large maples, we’re going to be running multiple emitters for each tree. And with drip emitters, we can add extra units as the tree grows.
What About The Lawns
I do not intend to water the lawns so I’m not using impact or pop-up sprinklers (circular spray jets that work back and forth.) There are several issues here I should address:
The first is that I’m not worried if the lawn goes brown. It will survive.
It’s basically a hay field that’s been mowed and my priority since moving in has been to get the vegetable and flower gardens sorted out. Given the level of construction that’s gone on (basement/siding/roof) it’s a wonder we have any gardens left. 😉
The second is that our soil depth isn’t deep enough to run popup nozzles so we’d have to use a higher number of impact sprinklers set on the edges of the lawns. They’ll be run over by cars, mowing machines and assorted grandchildren.
The third is the evaporation with overhead sprinklers is high and it’s a waste of water.
Let the lawns fend for themselves.
But you want to water your lawn.
Watering a lawn will take overhead impact sprinklers rotating back and forth. The principles are the same. Simply treat each overhead sprinkler as an emitter (the flow rate varies with each sprinkler and can usually be adjusted)
My sense is that some of you are going to get very confused about zones and what sizes of emitters etc. Here are several good resources (the Lee Valley links are particularly good as they give you emitter sizes) 🙂
This is an excellent consumer resource for designing your irrigation system.
You can download the irrigation guide directly to your computer
1) Draw out your garden in a rough way.
2) Determine how many zones you might want
3) Decide on what kind of emitter you want for each zone. (You don’t have to worry about how large an emitter is at the moment. Simply decide if you want soaker hose or a drip nozzle system to water the zone) Write this down as well.