How to schedule irrigation for a newly planted garden

A newly planted garden brings together plants with different roots and different needs. Mature trees, shrubs, perennials and lawn should not be given the same run time or the same frequency.

Nor should the initial programme stay unchanged for years. As the roots spread, watering needs to reach a larger area and become less frequent in several zones.

Scheduling starts with flow rate and soil, not just with minutes.

Mature trees need deep volumes and intervals matched to the drainage.

Newly planted shrubs and perennials have small rootballs and can dry out faster in the first few weeks.

Lawn is shallow-rooted and has a pattern of its own.

When these plants share a zone, one of them gets the wrong amount of water. The design should separate circuits wherever possible.

A west-facing area on sandy soil loses water faster than a shaded bed on clay.

Even with the same plants, zones may need different programmes.

Slopes also have their own run-off and exposure. Application can be split into cycles to allow infiltration.

The zoning should reflect the site and not just the visual boundaries of the garden.

Ten minutes do not deliver the same volume through a dripper rated at two litres an hour, an adjustable emitter or a sprinkler.

Record the rated output and confirm it on site. Pressure, line length and clogging all change the result.

The number of emitters per tree or shrub goes into the calculation.

Without this information, the controller shows time, but not the water actually applied.

Automatic irrigation does not necessarily replace the initial soaking.

Each rootball should be wetted and the soil settled. A hose lets you deal with areas the emitters do not yet cover.

From then on, the automatic system maintains and keeps pace with the planting.

The first watering also shows up drainage and leaks.

Trees are watered at several points around the rootball.

The water needs to pass right through the root mass. A short burst of lawn sprinkling is not enough.

At first, the emitters sit close to the root area. As the tree establishes, they are moved outwards to encourage the roots to spread.

Frequency varies with the species, the rootball and the soil.

Drip irrigation should wet the original root volume and the space between plants.

Once the planting closes up, shade reduces evaporation. The programme can be adjusted.

Shrubs with different needs should not be mixed in the same zone simply because they are close together.

In the first few weeks, the small root volume needs attention.

Watering too far apart causes losses before the roots have explored the bed. Keeping the surface constantly saturated, however, encourages shallow roots and problems.

Frequency is reduced gradually.

Established grasses can tolerate a longer interval than perennials that have just been planted.

Lawn needs even sprinkler coverage and a programme of its own.

Overlap, pressure and wind all affect coverage. Catch cans help to identify differences.

Watering every day for a short time encourages shallow rooting. The programme should suit the type of turf, the soil and the season.

A rain sensor avoids unnecessary applications, but does not confirm that the rainfall has wetted the whole profile.

Soil moisture sensors can improve decisions when they are correctly positioned and calibrated.

Weather data help to adjust for evapotranspiration. Observing the plants and the soil is still necessary.

On slopes and compacted soils, water can run off before it soaks in.

The total time is split into several cycles, with a pause between them. The volume stays the same, but the application becomes slower.

This approach does not correct poor drainage. It only improves the way water gets in.

Watering in the cool of the day reduces losses to evaporation and wind. Early morning is often suitable.

Prolonged night-time watering over foliage can raise humidity on some plants, although drip irrigation reduces that effect.

The timing should also allow leaks and operation to be observed.

Small inspection holes are opened beside the roots to see how deep the water has gone.

Look for run-off, puddles, dry emitters, pressure differences and water on paving.

The programme is corrected according to the results. Do not wait for widespread symptoms to appear.

In spring, growth increases demand. In summer, heat and wind call for closer attention. In autumn, frequency falls with rain and reduced activity.

Winter does not mean switching off without checking, especially with evergreen trees and in dry spells.

Adjustments can be monthly, or made when the weather changes significantly.

The programme for the first week is not the programme for the sixth month.

Gradually reducing frequency and increasing the wetted area helps the roots to spread.

The reduction should not be abrupt or based on a date alone. The soil and the growth show whether the plant is ready.

Someone should know who changes the controller and why.

Records of volumes, rain and problems stop several people making contradictory corrections.

Efficient irrigation comes from a well-divided system and from observation. The controller carries out instructions; it does not diagnose the garden on its own.

• How to water a mature tree
• Soil, water and drainage
• Maintenance plan

1. Principles of irrigation efficiency and plant establishment.
2. Literature on the hydraulics of drip irrigation systems.
3. Diaplant’s method for planting and maintenance.