Tents and Trees: A Solver's Strategy Guide

Updated June 2026

Tents-and-trees is one of those puzzles that feels intimidating on the first board and obvious by the fifth. The whole game is a conversation between two simple facts — every tree needs its own tent, and tents refuse to touch each other — refereed by the numbers along the edge. This guide shows you how to turn those facts into forced moves so you rarely have to guess.

The rules in one breath

You are given a grid with trees scattered across it. Your job is to pitch tents, one for every tree, following three rules:

• One tent per tree. Each tent sits directly beside its own tree — up, down, left, or right, never diagonally — and the tents and trees pair up perfectly one to one. No tree goes without a tent, and no tent is shared.
• Tents never touch. No two tents may be adjacent, not even at a corner. Every tent is surrounded by empty grass.
• The edge numbers are exact. The number on each row and column tells you precisely how many tents that line contains — no more, no fewer.

Always start from the numbers, not the trees

Beginners stare at the trees and try to place tents around them. Strong solvers read the edge clues first, because the extremes are free information. A row or column marked 0 contains no tents at all, so you can immediately fill every cell in that line with grass. That single move often removes the only awkward square next to a nearby tree, forcing its tent into the one direction that remains. At the other end, when a line's clue equals the number of cells that could still hold a tent, every one of those cells must be a tent. The edges are where almost every board cracks open.

Some cells can never be a tent

Here is a deduction people miss for far too long: a tent must always be next to a tree. So any cell that has no tree as an orthogonal neighbour can never hold a tent — it is grass, guaranteed, before you have placed anything. Sweeping the board once and greying out every cell that is not adjacent to a tree shrinks the problem dramatically and often leaves trees with only one legal spot left.

Place, then fence

Whenever a tree has only one empty neighbour left — because the others are grass, off the board, or already claimed — its tent is forced. Place it. Then immediately do the second half of the move that most solvers forget: mark all eight cells around that new tent as grass, because nothing can sit beside a tent, not even diagonally. This "place then fence" habit is the heart of the game. A single forced tent fences off up to eight squares, which strips options away from neighbouring trees and frequently completes a row's count for you, triggering the next forced tent. Chasing that chain is how the fastest solves happen.

Think in pairs, and watch for traps

Because every tent belongs to exactly one tree, it pays to think about the pairing, not just the placement. A lone tree jammed into a corner or against a wall has very few candidate cells — lock those down first. Conversely, be suspicious of a tempting cell that sits between two different trees: placing a tent there might satisfy your eye, but if both of those trees needed that shared cell, you have just left one of them with no possible partner later. When two trees compete for the same single cell, that is usually a sign you should be solving a different tree first, the one whose options are genuinely forced.

Use the no-touching rule as information

The no-touching rule is not only a restriction on where you may place tents — it is a steady source of new grass. Every tent you commit to converts a whole ring of cells into grass, and each new grass cell can be the deduction that forces the next tent or completes a count. On ujem the board helps you here: a tent flashes red if it is illegally touching another tent, and an edge number turns green the moment its line holds exactly the right number of tents. Treat the green numbers as a progress bar and the red tents as an instant "undo that" signal.

A reliable solving loop

1. Mark every 0-clue line as grass, and grey out every cell not adjacent to any tree.
2. Place all forced tents — trees with a single remaining neighbour — and fence each one.
3. Re-check the edge counts: any line that now has exactly as many candidates as its clue is fully determined.
4. Look for trees whose only partner is a shared cell, and resolve the forced one first.
5. Repeat. On a well-made board the chain of forced moves carries you to the end without a single guess.

Every Tents board on ujem is generated to have one unique solution, so the forced move is always there. The timed mode is really a race to see how fast you can spot it.