How to map irrigation zones in your garden

Why map before you install

Designing without a map is the fastest way to build an inefficient system. Without knowing exactly where each sprinkler goes, you end up with overlapping zones where they are not needed and uncovered areas you must water by hand. The map is the reference document for trenching, laying, programming and future maintenance.

A good map accounts for three variables: garden geometry (shape and dimensions), hydrozones (groups with similar water needs — see Hydrozones: split your garden to irrigate better) and physical constraints (paths, walls, trees). These three layers combined determine where every sprinkler sits and how zones are divided.

How to measure your garden

A laser measure is the fastest tool: you can survey a 500 m² garden in 10 minutes with millimetre precision. Start with the perimeter, then measure internal distances between fixed elements. Sketch it on paper in rough scale.

For irregular shapes, break the area into rectangles and triangles. Sum the simple areas for the total. A 10% measurement error is acceptable at design stage — it is corrected by adjusting sprinkler radii during installation.

Dividing by hydrozone

Group areas by similar water need. Lawn: high demand, frequent irrigation (3–4 times per week in summer). Shrubs and hedges: medium demand, twice a week. Flower beds: often drip-irrigated. Mature trees: deep, infrequent watering.

Never mix lawn and shrubs in the same zone — the lawn needs irrigation so often it would rot shrub roots. This principle directly determines how many solenoid valves you need — see Hydrozones: split your garden to irrigate better.

Choosing the sprinkler type per zone

Lawn up to 6 m wide: popup sprays with 180° or 90° nozzles. Lawn 6–15 m wide: popup rotors. Narrow beds along a wall: spray with strip nozzle (1.2 m wide). Vegetable garden and flower beds: drip or micro-jets. For the spray vs drip comparison see Pop-up sprinklers vs drip irrigation: how to choose.

Adjacent sprinkler heads must overlap by at least 50% of their radius: two spray heads covering 3 m must be no more than 3 m apart. This head-to-head coverage principle ensures uniformity — details at Head-to-head: why your lawn needs it.

Creating the digital map with SprinklerMap

Transfer your measurements into SprinklerMap: draw the garden perimeter, place sprinklers on the map and see coverage of every head in real time. Add paths, beds and obstacles as separate layers.

The advantage over paper is recalculability: move a sprinkler and coverage updates instantly. Export the map as a PDF to share with your installer, eliminating ambiguity about exact positions.

Common mapping mistakes

The most common mistake is ignoring slope: in a sloped garden, downhill sprinklers on the same zone receive more pressure — and therefore more water — than uphill ones. Mark any slope above 5% on the map with an arrow showing the downhill direction. At installation, these sections usually need shorter zones or anti-drain valves to stop residual water dribbling out of the lowest heads after shutoff.

A second common mistake is forgetting transition strips: the band of lawn next to a hedge or bed. These edges have hybrid needs — partial shade from nearby vegetation but still lawn underneath. If the strip is narrow (under 1 m), fold it into the adjacent lawn zone. If it is 2–3 m wide, draw it as its own micro-zone with 180° nozzles aimed back at the lawn.

Legend and symbols

A map that stays useful years later — for an extension, a repair, a change of ownership — needs an explicit legend, not just intuitive colours. Minimum convention: filled circle for spray heads, circle with an arrow for rotors, square for drip emitters or driplines, triangle for solenoid valves, rectangle for the controller. Label each symbol with its zone number and, if known, the sprinkler model.

Always add a north arrow and a graphic scale bar, not just the numeric ratio: if the map is printed or photocopied at a different size, the graphic bar stays accurate while the numeric ratio does not. Save the map both as a PDF and as an editable source file — on a system that lasts 15-20 years, someone (possibly you) will need to update it eventually.

Sharing the map with your installer

A complete map includes: position of every sprinkler with the chosen model, main pipe routing with diameter, solenoid valve and controller location, distances from fixed reference points.

An installer who receives a detailed map can accurately quote materials and labour, avoiding change orders mid-project. For full independent design guidance see also How to design irrigation for a rectangular garden.

How many sprinklers per zone: a quick calculation

Once you have the map and have chosen the sprinkler type for each zone, you need to confirm each zone stays within the available flow budget. The rule: total flow of all active sprinklers in one zone must not exceed 80% of your tap's maximum flow (measure this with a flow gauge).

Example: tap delivers 18 L/min; 80% = 14.4 L/min budget per zone. A 4 m pop-up spray head uses approximately 0.8 L/min; you can run 14.4 ÷ 0.8 = 18 heads in one zone. A 7 m rotor uses 2.5 L/min; you can run 14.4 ÷ 2.5 = 5 rotors per zone. Keep a 10–15% flow reserve — real-world values vary from datasheet figures.

Key takeaways

Map first, dig second. A complete garden map prevents the two most costly irrigation mistakes: dry patches from inadequate coverage and over-watering from mixing hydrozones. Measure the garden with a laser measure, divide into hydrozones (lawn, shrubs, drip), choose the sprinkler type for each zone, verify each zone's flow budget, then transfer to SprinklerMap for coverage visualisation before you buy a single component.

Common questions

How precise does the garden measurement need to be? ±10% is acceptable at design stage — sprinkler radii can be adjusted on-site by ±25% via the radius screw without changing nozzles. What matters most is getting the rough shape right so you can position heads at the correct grid spacing.

Can I design an irrigation system for an irregular-shaped garden? Yes. Break the irregular shape into overlapping zones of simple geometry — rectangles, L-shapes, triangles. Each zone can have its own sprinkler grid, and adjacent zones can share coverage at the boundaries. SprinklerMap handles freeform garden shapes and shows any uncovered areas in real time.

How do I handle a garden with different elevations? Sloped areas need rotors rather than spray heads (rotors apply water more slowly, reducing run-off). Each slope should be a separate zone from the flat lawn: slope and flat areas have different infiltration rates, and mixing them in one zone always results in one being over-watered.

Recommended products