How to design my backyard: the order that works

Every backyard design starts as a survey, not a sketch. Take one sheet of paper and put down the boundary first: the length and width of the plot, the house wall, the back door, every window that looks out at it, the drain covers, the outside tap, the shed, and any tree you intend to keep.

Two techniques cover almost everything. Pacing gets you a usable plan in ten minutes. Measure your own stride once along a driveway, then walk each boundary counting paces — a 750 millimetre stride over 20 paces is 15 metres, which is close enough to start allocating space.

Triangulation fixes anything that is not square. Pick two points you can find again, such as the two rear corners of the house, measure from each of them to the object you are locating, then swing two arcs at those radii on your drawing. Where the arcs cross is where the tree is. A backyard is almost never a true rectangle, and triangulation is what stops you designing for one that is.

A backyard survey is not finished until you know where the sun lands and where the water goes.

Photograph the yard three times on one clear day: around 9am, at midday, and around 4pm. Line the frames up and mark the shaded ground on the plan each time. The 4pm frame decides where seating goes, because late afternoon and early evening is when a backyard is actually used; the 9am frame tells you which corner gets breakfast light. If you cannot spare the day, the NOAA solar position calculator returns the sun's azimuth and elevation for your latitude on any date, which is enough to work out where a fence shadow will fall in July.

Water is the other half. Walk the yard within an hour of heavy rain and mark every place water stands, every gully and grate, and the direction the ground falls away from the house. Those marks constrain where paving can go far more than taste does.

The look is the last decision, not the first. Before any style question, write down every use the yard has to absorb: sitting, eating, cooking outdoors, small children, a dog, drying washing, bins, bikes, storage, growing food, and the pile of things that have nowhere else to live.

Then rank them honestly, because they compete for the same ground. A trampoline and a dining terrace both want the flattest, sunniest part. A dog and a deep perennial border both want the strip along the fence. Bins want to be near the side gate, which is also the only sensible route for a wheelbarrow.

A typical suburban backyard fits two of these properly and pretends to fit five. Choose the two that get used weekly rather than the two that sound best, size them at real dimensions, and let the rest take what is left over. That single act of ranking is most of what a garden designer is paid to do, and it costs nothing to do yourself.

A use with no dimension attached is a wish. Every activity in a backyard has a footprint, and the footprint is always the object plus the clearance around it.

Dining for six is the one people get wrong most. A 1.8 by 0.9 metre table is not the footprint. Add 900 millimetres of chair pull-back on all four sides and the paving has to be 3.6 by 2.7 metres — about 105 square feet — before a single planter goes near it.

A fire bowl 800 millimetres across, with chairs set back 900 millimetres and 850 millimetres of chair depth behind them, needs a clear circle 4.3 metres in diameter.

A 12-foot round trampoline is 3.66 metres of frame plus the 1.5 metres of clear space manufacturers ask for on every side: a 6.7 metre circle, which is most of a small yard gone.

Draw those footprints to scale on the survey, in pencil, and count how many actually fit. Usually it is fewer than the list.

Two invisible things decide the shapes on a backyard plan: where people walk, and what they see from indoors.

Take the routes first. Back door to gate, back door to bins, back door to shed, house to seating. Draw each as a straight line. People walk the shortest line available, and a path that ignores it becomes a bare track worn through the grass within one season — the same way a dog wears a 300 to 450 millimetre track along a fence whether or not anybody planned for it. Give a single-file path 900 millimetres of clear width, which matches the 36-inch minimum walking width in the ADA accessibility standards, and 1.2 metres anywhere two people should pass without stepping into the border.

Then stand at the kitchen window and at the back door and note where your eye lands. Put the focal point where the eye already goes, not where the plan looks balanced from above.

Levels are the part of a backyard nobody photographs and the part that decides the bill. Moving soil, building walls and taking water somewhere are the expensive items. Planting is cheap beside them.

Three numbers do most of the work. Ground should fall away from the house: the International Residential Code sets the minimum at 150 millimetres, 6 inches, within the first 3 metres of the wall. Paving wants a fall of about 1 in 80, roughly 12.5 millimetres per metre, so a 4 metre terrace sheds 50 millimetres across its width and puddles nowhere. Garden steps at a 150 millimetre riser and a 350 millimetre going mean a 600 millimetre change of level eats about 1.4 metres of the yard's length, which is why terraces on a slope always come out shorter than people expect.

Where the water goes afterwards matters too. EPA runoff guidance favours soaking it into planted ground on your own plot over piping it to the street.

Planting comes last because it is the only layer that can be changed cheaply, and it works best done in three passes rather than one.

The first pass is the boundary. Decide what the fence line does — disappears behind evergreen, carries climbers, or stays visible with planting held forward of it. That decision sets the backdrop everything else is seen against.

The second pass is structure: the things holding the garden together in February. Clipped domes, a multi-stem tree, two or three shrubs repeated rather than one of everything. A useful test is to picture the yard with every flowering plant deleted. What remains is the design. If nothing remains, there is no design yet.

The third pass is filler — perennials, grasses, bulbs — where the colour lives and where mistakes cost least.

Buy structure at a decent size and buy filler small. A 9-centimetre perennial catches a 3-litre one within two seasons at a fraction of the price.

Only now is a style question worth asking, because now it is being applied to a plan instead of standing in for one.

This is where a render earns its place. AI Landscape Design, the app Skyble Lab publishes, works photo-to-photo: it edits the picture you took from the back door, so the fence line, the house wall and the tree you decided to keep come back where they were, and you see 18 directions applied to your own yard rather than to somebody else's. The first 3 designs are free at full resolution, which is enough to settle an argument about whether the terrace should read modern or cottage.

Shoot from the back door and from the far fence looking back, then run both. A direction that only works from one end is not a direction. Treat the output as a palette test rather than a plan — the survey and the footprints are the plan. Download AI Landscape Design and try it on the photo you already have.

Some of a backyard is genuinely a weekend job and some of it is not, and the split has nothing to do with confidence.

Do it yourself: planting, mulching, turf, gravel over a compacted base, raised beds, edging, running a hose to a water butt. All of it is reversible and none of it holds anything else up.

Get somebody else to do it: any retaining wall over about 1.2 metres, which most jurisdictions want engineered and permitted; anything that changes where water leaves the plot; electrical work beyond a plug-in low-voltage lighting kit; large tree removal; and paving falls against the house wall, where an error of 20 millimetres puts water where it should not be for the next 30 years.

The honest test is whether a mistake is expensive to undo. A border planted badly costs you a season. A wall built badly costs you the wall, twice.