Location
The plot
Leave at 0° for a north-up plan. Set it to the compass bearing your garden runs away from the house, and the plan lines up with the real world.
GroundLawn is easier to read at a glance; plain gives higher contrast for printing or for saving an image.
Things that cast shade
Click an item on the plan to select it, then drag to move.
Selected item
Analysis date
Garden & plot shade simulator
Lay out your boundaries and anything that blocks the sun, then see where the shade actually falls — and which corners stay sunny all day.
Shadows at 12:00
What the weather typically does to this
Sun hours through the year
at the marked spot on the planThe probe is the crosshair on the plan — click anywhere to move it to the patio, the veg bed, or wherever you are actually deciding about. The solid line is the sun that spot receives; the faint line is what it would get with nothing in the way.
How the shade is calculated
Each building and fence is projected from its top edge along the exact sun direction onto flat ground, and the shadow is the convex hull of the footprint and its projection. Trees are modelled as a raised sphere of foliage on a clear trunk, so at a low winter sun the shadow lands well away from the tree and light passes underneath — which is exactly what long winter tree shadows do in practice.
Mark a tree deciduous and it stops casting shade outside roughly mid-April to early November, mirrored for the southern hemisphere. Bare branches do still cut perhaps a third of the light, so winter figures are slightly optimistic — but far closer than treating a bare tree as solid. An evergreen canopy is treated as solid all year, which is slightly pessimistic. Sloping ground is not modelled at all: a plot that falls away from a building gets more sun than shown, one that rises gets less.
Common questions
What counts as full sun, partial shade and full shade?
The convention on plant labels is six or more hours of direct summer sun for full sun, roughly three to six for partial shade, and under three for full shade. The heat map here uses the same six-hour line, so you can read a planting plan straight off it. Bear in mind the labels assume summer: almost every garden falls into deep shade for part of the winter.
How do I measure the height of my house or fence?
Fence panels are sold in standard heights — 1.8 m is the most common, 1.2 m for a low boundary. For a house, count storeys: a typical two-storey UK home is about 5.5 m to the eaves and 7–8 m to the ridge, and a bungalow around 3 m to the eaves. If you want to be exact, photograph the building next to something of known height and scale from that.
Does it handle a sloping garden?
No — the ground is treated as flat, and this is the biggest limitation of the model. A garden that falls away from the house gets meaningfully more sun than shown, because the shadow lands on ground that has dropped below the shadow line. One that rises toward a boundary gets less. On a noticeably sloping plot, treat the output as indicative rather than measured.
How are deciduous trees handled?
Mark a tree deciduous and it stops casting shade outside roughly mid-April to early November, mirrored for the southern hemisphere. That matters a great deal: an oak that shades a patio all summer may be irrelevant to whether your winter greenhouse works. Bare branches do still intercept perhaps a third of the light, so winter figures are a little optimistic.
Can I use this for a planning application or a right-to-light dispute?
Treat it as a well-founded starting point, not a survey. Formal daylight and sunlight assessments follow published methodologies using measured building heights, site levels and surveyed boundaries. This tool uses the dimensions you type in, so the output is exactly as good as your measurements — useful for a conversation with a neighbour or an architect, not for a planning committee.