Updated 11/27/2015 at 4:15PM
Introduction to Irrigation
Irrigation in the landscape is an absolute must. No matter what type of plant material or arrangements you are considering, you must consider irrigation along with it. We all know that the typical St. Augustine lawns with shrubs and trees require regular irrigation. But what do we do about drought tolerant plants, Florida Friendly plants, or even Florida Natives? The answer depends on areas such as your choice of plant material, your site conditions, and your soil profile. We will discuss these areas below, but first we must discuss establishment.
Establishment of plant material involves making the transition from pot to ground smoothly, without a reduction in plant health. I have an area that focuses on this topic, but it needs mention here too. Any plant, whether it is native, drought tolerant, Florida friendly, or any other such moniker; will require supplemental irrigation to become established. The establishment period will take 6 months to 2 years depending on plant type and size. Any native or drought tolerant plant can make this claim because of the extensive root system it develops over time. Deep and wide, this root system is one aspect that allows these plants to survive during extended periods of drought. Establishment irrigation allows the new plants to survive while they are getting their roots out.
We will briefly discuss some major areas that affect irrigation selection. Choice of plant material, your site conditions, and your soil profile are three important considerations. Selecting plant material that is not only appropriate for the site, but is also physiologically adapted to periods of drought, will be essential if you decide to go this route. Your site condition must also be evaluated. Primarily, consider how much sun light you get, especially during the summer months when it is directly overhead and most intense. Many plants can survive not only in sun but also in partially shady conditions. The same plant in partially shady conditions will experience less water stress than in full sun. Finally, you must consider your soil profile and its capacity to hold water. If you have the typical sandy soil found throughout Florida, then you can expect it to drain water relatively quickly. There are some instances where there is a lot of organic matter or even clay in present. These will both increase the water holding capacity of your soil, requiring less irrigation. Dig up and inspect the soil in your project area to find out.
If you have an existing system: The first step is to evaluate the existing system to determine if it is functional and working efficiently. If it has been operating up this point, then make sure to include an inspection for coverage and leaks. Turn on each zone and let it run for a long enough period of time to make sure it is calibrated to irrigate that zone properly. If you cannot get the system to operate, contact a licensed irrigation contractor. See below for considerations in collecting bids. Complete any irrigation repairs required before proceeding with your renovation. If there is a rain sensor, inspect and clean it. If there is not, then make sure to install one if your controller has that option. If your controller does not have this option, consider upgrading.
If you do not have an existing system: At this time it will be important to step back and evaluate the scale of your work. If you do not have irrigation, chances are your landscape is not lush and tropical with green lawns. You may have bahia grass with a mixture of weeds, and even a few shrubs and trees. These types of established plants can survive without supplemental irrigation. But if you are looking to upgrade, irrigation will have to be addressed in some fashion. There are a few different types of irrigation. They include drip, overhead, and micro to name a few. These will be discussed below.
Before you consider installing an irrigation system of any type, think about the use of drought tolerant and native plants that are suited to your site conditions. There is a small list of plants that can survive extended periods of drought without supplemental irrigation. However, please keep in mind that even these plants must receive irrigation to become established. Do not count on yourself or anyone else to hand water new plants to establishment. Depending on the size of the plant, this process may take 6 months up to one year and must be performed on schedule. So, make sure to arrange some sort of irrigation based on what is described below. Once your plants are established you can simply turn it off.
Next, you will need to ask: What are you looking to accomplish with your landscape? If you are simply renovating a small area, replacing some sickly shrubs, or even planting just a few trees; then your irrigation goals will be different than if you are redesigning your entire landscape. Let’s talk about smaller projects first, and then we’ll proceed to larger ones.
Small projects: If you are renovating a smaller area, then it may not be cost effective to install an entire irrigation system. In order to install the typical in ground irrigation system, you must tap into the main water line from the street. This not only requires a permit, but the expertise of a licensed irrigation contractor. Do not attempt to do this yourself, keep in mind you would be messing with the public water supply for all your neighbors.
You can, however, run a small simple system off the hose bib. Go to any hardware store and a purchase a splitter (so you can still use your hose), a simple battery operated programmable timer, and a drip line. You easily hook them up to your hose. Making sure all gaskets are installed, and there are no leaks. So make sure to tighten everything very snug, but do not over tighten. Get a long enough drip hose to go up one side of the arrangement, and down the other. Drip hoses have minimal coverage area, so both sides of the root ball need to have some of the drip hose on it.
Set up of the timer is easy. Program it to irrigate every day for the first week or two, twice a day if it is really hot and dry. After the first week or two, reduce the frequency down to every other day. Then systematically reduce it from there until you are at the desired frequency. Unless you have purchased very drought tolerant plants, or have planted in a little shade; you will most likely need to continue irrigating at least once a week. Don’t forget to mulch! This conserves soil water by reducing evaporation from the surface. Drip hoses typically have a life span of less than two years, inspect regularly for cracks and leaks and replace immediately.
If you are installing a tree(s), you can use a water bag. This bag wraps around the trunk of a tree, and zips up the side. You fill the bag up once a day, and it slowly drips out the bottom over a 6-12 hour period. These bags are not appropriate for shrubs and small plants.
Do not attempt to run an underground or permanent PVC irrigation system off your hose bib. The transition from hose to PVC is not reliable, tending to leak, and there is usually not enough water pressure at the hose bib to run this type of system.
More extensive projects: If you are renovating a larger area such as the entire back yard, or the entire landscape, you will need to consider hiring a licensed irrigation contractor. But first, a word of warning: It is not good practice to try and establish an extensive landscape project using drip hoses off the hose bib. They are also not meant to be permanent, with a lifespan of less than 2 years.
You should collect bids from several irrigation contractors, just as we did for the design and installation process. Your contractor will be familiar with code requirements in your area. You should also check with your HOA for any requirements they may have. As we stated above, he will need to connect to the public water supply. Many municipalities offer reclaimed water for irrigation purposes, which saves money on the water costs. This is an excellent choice, unless the irrigation will be applied in living area where overspray may affect you. If you are landscaping around a pool, or small garden that includes sitting and eating area right next to irrigation emitters, you may want to consider using the main water supply in a separate zone.
This type of system will consist of an irrigation controller mounted and wired into the house electrical system, a set (or manifold) of valves wired to the controller, and a system of PVC pipes buried underground (about 12” deep). The underground PVC pipes run to emitters that are recessed into the ground and rise up under pressure to spray water during the cycle. These emitters can be rotors or pop ups. Many contractors use risers in shrub beds to raise the emitter over the level of the shrubs so the spray reaches the entire planting bed.
Even if you are installing a Florida Friendly landscape with the goal of independence from supplemental irrigation, you will not only need to establish it, but you will also need to apply supplemental irrigation during extended periods of drought. This would include times when we don’t see rain for more than 7-10 days, and when temperatures are high. This usually occurs during the spring, but may also occur during the summer and fall. There is a small range of plants that can survive these conditions without supplemental irrigation, so unless you have selected these plants, you will need to apply some supplemental water during these times to maintain acceptable plant health.
You may have selected a mix of Florida Friendly and tropical plantings. In this case you can use a technique known as hydrozoning. When you hydrozone, you organize the plant material with high water needs into one area. This area can be set up on a separate zone to be irrigated more often than drought tolerant zones. This will allow you to save water and money, while also adding a tropical feel to your landscape.
You will also need to know how much lawn grass you are planning to install. Extensive lawns, especially St. Augustine will not survive without supplemental irrigation during drought periods. With large lawns, rotors will be a better choice over pop ups. Your irrigation contractor will know this, but make sure that you have discussed it with him. If you have an extensive lawn area in full sun, then bahiagrass would be a more drought tolerant option. Once established, bagiagrass can survive without supplemental irrigation. If you desire a more lush lawn, give it a shot of water every 7-10 days during periods of extended drought.
If you are going to install the typical St. Augustine lawn with tropical palms, common ornamentals, shrubs, and annual planting beds; then you can plan on consuming more water. Given that, system efficiency and regular maintenance will be the key keeping water use to the lowest levels possible. Also, these types of landscapes typically do better with a bit of shade, the best being a break from the midday sun. The shade will help to reduce water demands. So make sure to integrate a few large trees such as live oak or southern magnolia.
Micro irrigation: An excellent option to overhead irrigation systems is micro irrigation. Micro irrigation uses poly tubing that lies above ground. It can be partially covered by the mulch, as long as the emitters are not covered. The idea is that the plant material grows up around it, eventually concealing the tubing.
Micro irrigation uses small emitters inserted directly into the poly tube, or emitters connected to the poly tube with ¼ tubing and staked into the ground. These emitters are rated at gallons per hour as opposed to gallons per minute ratings that are given to overhead risers, pop ups, and rotors. Therefore, the use of these emitters has the potential to save quite a bit of water and money. Employing either a downward or a horizontal spray pattern, these emitters also serve to keep water low to the ground and off the foliage as plants grow tall. This serves to reduce water loss due to evaporation while also reducing incidence of disease.
Micro irrigation cannot be used in lawn grasses, since the emitters need to retract under the turf for mowing. Micro should be used in planting beds and other gardens. The micro system should be on its own zone. It is bad practice to mix micro systems and overhead emitters on the same zone. The micro irrigation zone will also require different frequency and duration than overhead zones. This system also requires more frequent inspection because the emitters can be broken/damaged more easily that pop-ups. Make sure to integrate this into your maintenance schedule.
Budget: At this time collect the bids and see if this fits into your budget.
In the end, your irrigation system should be configured around your landscape design. Whether you have an existing system or are installing a new one, make sure it is set up using the techniques outlined above.
Scheduling: Once your irrigation system is installed and set up, you will need to schedule the frequency and duration for the different zones. As stated in the introduction, you will need to irrigate more frequently immediately after installation, and then taper the frequency off from there.
Irrigation for establishment is covered in more detail in the Establishment section.
Once established, you will need to set up a regular schedule. Most municipalities restrict irrigation to twice per week during certain times of the year, and once per week during other times. Some turn off irrigation water altogether during the cold months of January and February. Irrigation days are typically Wednesday/Saturday or Thursday/Sunday depending on whether or not you have an odd/even address respectively. Scheduling irrigation events is usually prohibited between the hours of 10am and 4pm. The best time to schedule your system to run in early in the morning, perhaps around 4 or 5 am. This will reduce evaporation losses, and keep your foliage from being wet all night. It is not recommended to irrigate in the evening. If you do so, the foliage stays wet for a longer period of time which increases the incidence of disease. You will need to check with your local extension office to find out the details for your municipality.