Irrigation product guide

There are many ways to apply water and types of equipment to use. Products to help you water your garden fall into four groups:

• In-line systems with pop-up sprinklers or spaced risers and a variety of micro sprays and drips
• Soak, or seep hoses
• Hose / sprinkler combinations, and;
• Rainwater storage tanks

And don’t forget the humble watering can, it may be all you really need if you have a small garden or just a few plants in pots. The most wasteful way to apply water is to use a hose with your thumb over the nozzle. This produces large droplets or jets of water that damage the surface of the soil and water tends to run off rather than soaking in. Having one large sprinkler that waters everything including the house and drive is not good either.

Remember, your aim is to wet the soil, not the plants and supply enough water to replenish soil reserves without overdoing it. Water in the evening or early morning, otherwise the sun will evaporate some of your valuable water. The amount of water lost to evaporation is greatest when water is sprayed and lowest when it seeps or drips. However, on sandy soils there is little sideways movement of water from drippers and seep hoses so you will need to space your equipment closer together. Approximate spacings: sand 1m, loam 1.7m, clay 2m.

Some equipment may take a few hours to install but will save you time and waste less water than others. The best product for you depends on your budget, the size and layout of your garden and the type of plants that you grow.

Stick to the rules: one sprinkler system or hose at a time, only water on alternate days according to your street number (specific days of the week in Upper Hutt), only for two hours in the early morning or evening. These restrictions apply year round in Wellington and Upper Hutt and during daylight saving elsewhere.

In-line irrigation systems

Cheap starter kits make these easy and affordable for everyone, and you don’t need special tools or skills to install them. They are also cheap and easy to expand. The microjet sprays are ideal for flowers, vegetables and plants with shallow roots. The range of full circle, half circle and quarter circle spray, misting and drip nozzles means you can conserve water by delivering the right amount to the right place.

Water flow is key as it dictates the number of microjets or drippers that will operate efficiently from one tap and the length of time to apply water for to achieve wetting to a depth of 10cm. There will be instructions on how to measure water flow in your start up kit or in an irrigation product guide available from garden product retailers.

Soak, seep or weep hoses

These allow water to sink slowly and gently into the soil so there will be less soil erosion and loss to evaporation. The downside is that you cannot see the water and may leave the hose running for too long. You only need to wet the top 10cm of soil. Soak hoses have small holes along their underside. The hose is placed on the ground with the holes down. Seep hoses (sometimes also called weep or leaky hoses) are made of dense spongy material and the water oozes out uniformly along their length. The soil's natural capillary action draws the water in. These hoses should be placed under your mulch in direct contact with soil and can even be buried in the soil without clogging.

Hose-sprinkler combinations

This system can be very wasteful of water but is quick to install. You can have the system up and running in minutes but it can be tedious and time consuming moving it around the garden and it often doesn’t put the water where you want it. Remember, you may only run one hose at a time.

Rainwater storage tanks

Also known as water butts, these are relatively new in New Zealand. For this reason, and because they are expensive, there are not many options to choose from. They hook into the down pipe from your roof gutter and divert water from the roof into storage. There is a double bonus in doing this, you reduce flood flows in streams when it is raining and save valuable treated water during dry spells.