The Basics of Drip Irrigation

Now you have finished designing your garden, you know exactly what you are going to plant and where, it is now time to decide on how to make sure that everything grows. One of the most important things to consider is how you’re going to water everything.

A watering can or a hose are both good ideas, but they are indiscriminate, exceedingly hard work, and can often damage many plants, especially in their first stages.

Drip irrigation small
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If your garden is large this can also be a time-consuming and back-breaking task. By far, the most effective method is a drip irrigation system.

Many areas with certain climatic situations impose watering restrictions at certain times of the year. It is, however normal practice for most areas to allow unrestricted drip irrigation.

There are two types of drip irrigation systems. They both need a water supply, a way of regulating the water, and different sized tubings that connect to lead to a delivery nozzle.

It is the delivery nozzle that emits the water a drip at a time to the garden.

Delivery nozzles are normally marked showing how many gallons per hour will flow through them. I find it best to use this figure as a guideline since there are many factors that will affect the quantities of water that will flow through them.

Devices that control the water flow are available as cheap basic controllers that cost a few dollars, or as a state-of-the-art computer and remote controlled unit that can cost hundreds of dollars.

Plastic tubing is available in many sizes and both systems need the use of decreasing pipe size from the water supply to the delivery nozzle.

The size of the tubing to be used for the system depends on the dimensions and flow of water that the system is required to provide.

The tubing is laid from a water supply into the area to be irrigated. The initial tube is connected to a tube with a reduced diameter that is then connected by using elbow and T connections to allow the tube to be laid backwards and forwards across the area to be irrigated.

Emitters can be connected to this pipe or to a smaller pipe to enable the water to be dripped exactly were needed.

Another technique is to lay a polyurethane tape called a t-tape that has emitters connected along its length that allow a gentle flow of water along the length of the tape.

This layout is fine for vegetables or flowers, however, if trees are being irrigated, it is best to make a circle of tubing around the trunk to which four or five emitters can be connected.

A spray or misting watering system emits large quantities of water indiscriminately, perfect for a lawn that just wants plenty of water. However, this type of irrigation is indiscriminate, and uses more water than is required for most vegetable gardens.

A drip installation emits low levels of water over a longer time, and is ideal for delivering a specific quantity of water to a specific area of the garden.

drip irrigation for seedlings

It is important to be able to quantify how much water the system will deliver and be able to adjust this quantity according to the different zones in which different plants are being cultivated.

Using a drip irrigation is thought to increase plant productivity by up to 30%, while using 50% less water.

Above Ground

The first type of drip irrigation system is one that is installed on the surface of the ground.

An above ground installation is a good idea as it permits the watering points to be moved and adjusted according to what is planted and where they have been positioned.

Flexibility is important in domestic growing environments where planting will change during the seasons. I use above ground irrigation for my trees and vegetable patch.

I have mainly olive and almond trees. While the almond trees don’t need watering, the olives do need extensive watering, especially when they’re in blossom.

An above ground installation is important to me, as a bulldozer comes to plow the field every spring to remove the weeds, and to break up the surface, allowing easier water penetration.

With the system being above ground, it is easy to remove it for plowing, and it also allows me to check through the components of the system when I replace it.

As the system is laying on the surface of the ground I usually keep this all in place with short pieces of stiff wire that is bent into the shape of a U.

I also use an above ground system on my vegetables since I have a virtual year round growing capability, consequently there is always something different in the ground.

Different plants need different spacing and different amounts of water. The above ground system provides me with the level of flexibility and adaptability that I need.

Below Ground

A below ground drip irrigation system has the benefit of delivering the water directly to the root system which is actually where it’s needed. This type of system is best for those that consistently grow particular crops.

With no change in water requirements, there is little need to change the system. It is necessary to plan an underground water system at the same time as considering what is going to be planted as the system requires installing before any planting can be carried out.

Quantity of Water and When

The burning question on any gardeners mind is how much to water should I use and when should I be applying it? This question does not, however, have a straightforward answer as it is subject to many variables.

Climate

The climate is a very obvious factor that has a large effect on watering. Hot, dry areas will demand a higher level of water compared to cooler, wetter areas.

Due to the frugal nature of drip systems, they are perfect for areas that experience long rai- free periods, especially if a water availability is limited.

Seasons

Different seasons will see different plants being cultivated and consequently different quantities of water will be required.

A planting calendar is a good idea to be able to plant everything on time, and it can also be used to plan a watering program.

For locations that have a regular rainy season watering will not be required during this season. However, most geographical locations have changing seasons and variable conditions within those seasons.

Consequently, when conditions change watering routines will need to be changed to take into account these changes.

Type of Cultivation

What is being grown also has a profound effect on the quantity of water required. Plants have very different and specific requirements for the quantity and where that water is needed.

Most mature vegetables prefer the soil to be moist to approximately 2 inches deep, while a younger plant requires less depth, if it is too dry or too wet they will not flourish.

Another important factor is the microorganisms in the soil, since these are essential assets that the gardener must nurture. Too much water can drown them.

Too much or too little water results in dead plants. An experienced gardener will recognize the signs of too much or too little water by watching the progress and condition of the plants. Leaf color is a good indicator of over- and under-watering.

When to Water

The question about when to water also requires careful thought. In a hot, dry climate any daytime watering, especially above ground could result in high levels of water evaporation which will result in insufficient water reaching the plants.

Evaporation is more prevalent in a misting irrigation system while a drip system will allow water to be absorbed by the soil.

Mulching certain areas is also an option to help reduce the quantity of water that is lost due to evaporation from daytime watering.

Clearly in this environmental situation nighttime is the ideal time to water.

However, in other areas, nighttime can result in large quantities of water being deposited from condensation, which could result in over watering if irrigating at the same time.

Using a domestic water supply for nighttime irrigation will avoid problems with fluctuations in the pressure and so the amount of water supplied will be constant and quantifiable. However, if pumps are being used nighttime watering may result in annoying noise.

Connection to a normal water utility although viable does create a problem in that the pressure of this system is far too great, it will certainly pass to much water through and will most likely cause the drop emitters to disconnect. A solution to this problem is to connect a device called a pressure reducer, this will reduce the pressure to a level that is satisfactory for the system.

If anything is connected to a public water supply, by law a device must be fitted to ensure that water cannot flow back into the water system. This is to prevent the public water supply being contaminated.

Water Supply

A consistent supply of good water is essential for this system to work effectively. Exactly where the water is on the land is an important consideration. It’s possible to connect the watering system to a home utility supply, however this is a costly option.

Rainwater harvesting and storage is a practical solution for many areas depending on the local climate. Some U.S. states offer advice and monetary aid to install and use these systems.

If the property has a natural water supply such as a well or a stream this water is ideal providing the relevant water rights or permissions are in place. This water supply will possibly need to incorporate a filtration system to prevent any debris in the water from blocking the drip nozzles.

A further consideration is that the water may need to be pumped to a more convenient location. An easy option is to install a tank that will contain a sufficient supply of water for a certain period.

The pressure of the water is a very important factor since if it is insufficient water will not flow from the system. If the header tank is in a raised place it may have enough pressure depending on the size of the system. This will avoid the need to install a pump.

For every 3 foot increase in the elevation of a header tank the pressure within the tank will increase by about 1 pound (0.45 kg). This is also an important factor when deciding on the size of the tubes required to make an efficient installation.

Depending on what the crop type water from a well or a stream may require the pH adjusted to avoid serious damage to the plants.

An automatic system is the best method to make sure that the correct amount of water at the proper rate is consistently applied.

The amount of water required will change according to the season, the crop and the growing stage of the crop, consequently it is important that any system is easy to check and adjust accordingly.

Fortunately, I have a good supply of water with a spring that is active during a part of the year, and a well that I can use at any time.

I pump water using solar-powered pumps into a 55000 LTR. storage tank, from which I can then pump into a raised storage tank that supplies the irrigation system by gravity.

Advantages

Efficient watering

Recent research indicates that regularly providing just enough water at the correct depth is the most efficient watering regime that will create the ideal growing conditions for most plants.

This method of watering helps to reduce the amount of water that is being applied to the leaves of the plants.

Preventing excess water on the leaves helps to cut problems such as leaf mildew. Keep in mind that by only watering the plants and not the general area there’s less opportunity for weeds to flourish.

Fertilizer

This style of irrigation is also the perfect solution for fertilizing crops using a liquid fertilizer in a targeted, quantifiable and consequently cost-effective way.

Expansion

The possibility of the system requiring expansion should be taken into account at the design stage, since integrating this possibility into the design of the system will avoid the system needing replacement for what should be a simple upgrade.

By doubling the diameter of a pipe it is possible to quadruple the rate of flow supplied by the system.

An above ground installation is easy to extend. Likewise, a below ground installation is also easy to extend providing this has been factored into the system at the planning stage.

Flexibility

Drip irrigation is also a very good way to irrigate other areas besides gardens. Any area where tubing can be laid can benefit from it. Raised beds, greenhouses and especially hanging baskets can be irrigated in this way.

It’s particularly good for hanging baskets since with the combination of heat and the air that flows around them they become dry very quickly.

Trying to water a hanging basket with a watering can is not effective as the water does not soak into the basket leaving it still dry.

Disadvantages

The main disadvantage with this system is that it requires extensive quantities of different sized plastic piping, a variety of connectors and fittings, and a control device.

It’s difficult to make sure that connections fit correctly and are leak-free. Any leaks will alter the dynamics of the system.

The drip nozzles can easily become blocked by external or internal influences, although on an above ground system, it is relatively easy to see and repair.

An adequate sustainable water supply is also essential, but may prove difficult in some climatic conditions.

Large garden or growing area could mean an extensive and costly system. Consequently, it is perhaps preferable to reserve for vegetables and trees while planting flowers that need less watering.

flower pots connected to  a drip system
By No machine-readable author provided. Blumenfischer~commonswiki assumed (based on copyright claims). – No machine-readable source provided. Own work assumed (based on copyright claims)., CC BY-SA 3.0, Link

In an area that suffers low temperatures or freezes it may be necessary to drain the system and to cap it to prevent water from freezing and busting the pipes.

An above ground system does however leave the system exposed to the weather. For those living in hot, arid areas the constant exposure to the sun has a negative effect. It can heat the water in the pipes, and the sun will damage the plastic.

Animals such as dogs will chew anything that they shouldn’t, and an above ground system may become their new favorite toy.

An underground system require careful consideration as to what is going to be planted and where, since, when installed underground, it is a complex, costly and costly to alter it.

Without interference, the piping has a life expectancy between 2 and 15 years, so remember when calculating the design and installation to take this into account as part of your long-term irrigation plan.

Summary

As we have seen, drip irrigation in either of the methods of installation is an effective and economical way of watering gardens.

The installation cost of a drip irrigation system will obviously depend upon the size of the area that requires irrigation, and whether you buy the installation in a kit form, or make your own from scratch.

Drip irrigation kits are available to buy from many sources, and are great for small scale projects, but don’t always offer the flexibility for a larger scale or a more complex installation.

The tubing and connectors are not particularly expensive, however a control device can be costly. Take into account the possible extra cost of equipment such as pumps to move water from the source to where it’s required.

Whether you make your own budget system or buy a complete kit you will be rewarded by the quantity and quality of the crops that you are able to grow.

Do you have a drip irrigation system? Did it make a different to the yield your garden produces? Let us know in the comments below, and don’t forget to pin this for later!

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