Tree spacing calculator: how far apart, how far from the house

It takes the mature crown spread of a species, as published by a university extension service or a public plant guide, and turns it into three planting distances: tree to tree, tree to house, and tree to overhead line. Then it counts how many trees fit the row or block you have. Spread is the right starting point because two crowns touch when their trunks are one full spread apart. Everything else is a choice about how much overlap you want.

1. Pick the species, or choose Custom and type the mature spread and height from the nursery tag.
2. Plan for the top of the range unless the site is poor. A tree in good soil grows to the top number.
3. Choose how close the crowns sit: a screen overlaps, a shade row touches, a specimen gets air around it.
4. Pick the pattern and enter the row length, or the length and width of the block.
5. Read the spacing from the tag, then the setbacks and the count underneath. Print it for the planting crew.

These are the published mature sizes the calculator uses, with half the top spread already worked out because that is the house setback. The range is wide for good reason: a white oak in deep bottomland soil gets to 80 feet across, the same tree in a compacted lot will not come close.

A single row is a property-line screen or a driveway allée: the count is the length divided by the spacing, plus one for the tree at the start. A square grid is the simple block layout for an orchard or a windbreak. A triangular layout shifts every other row by half a space, so the rows close up to 0.87 of the spacing while each tree keeps the same distance to its neighbours.

The Arbor Day Foundation's rule is to plant a tree half its total spread from the house, so the branches do not rub the structure. Ask Extension gives 10 feet as the general minimum for any tree, so the calculator uses whichever is larger. Height is the second check. The City of Redmond's planting guide sets distances from a two-story house by mature height:

Roots do not stop at the drip line. UF/IFAS notes that weeping willow roots spread about three times the distance from the trunk to the canopy edge, that American elm forms large surface roots, and that a white oak trunk flares enough to lift sidewalks in tree lawns under eight feet wide. Give those three the top of every range. A tree planted too close is the removal quote you get in twenty-five years.

Redmond allows trees under 25 feet at maturity beneath power lines and nothing taller. For tall-growing trees, PPL Electric tells customers to plant at least 50 feet from the lines. Every species in the list here outgrows 25 feet, so the calculator never puts one under a wire. Your own utility's rule is the one that counts, so check it before you dig.

A 120-foot property line, river birch, crowns just touching. The top of the published spread is 35 feet, so the trees go 35 feet on centre: 120 ÷ 35 = 3.4, rounded down to 3 spaces, plus the first tree, is 4 trees. Each trunk sits at least 17.5 feet from the house, and because river birch tops out at 50 feet, none of them goes under a wire. Switch to a screen and the spacing tightens to 26.3 feet, which fits 5 trees.

Set the root flare at grade, then put down a mulch ring. The mulch calculator gives the yards for a ring or a whole bed. Structural pruning starts in the first few years. See when to prune for the timing by species.