Deer Fencing & Garden Enclosures on San Juan Island

Deer pressure here is not like deer pressure on the mainland. The islands lost their cougars and wolves in the 1800s and never got them back, hunting is limited, and the result is a black-tailed deer population that lives at density with no meaningful predator, in yards, on roadsides, and through your vegetable beds at four in the morning. Every long-term islander has the same story about the rose bushes or the tomatoes or the newly planted apple whips. Fencing is the only thing that reliably works. Sprays wash off in the first rain, motion deterrents get learned within a week, and the deer-resistant plant lists are aspirational at best when browse pressure gets high in late summer.

Height first, because it is the decision that determines whether the fence works at all. For a large open perimeter, plan on eight feet. Black-tailed deer are not enormous but they clear a six-foot fence without much effort when they want what is behind it, and a fence they can jump is worse than no fence because they get stuck in it. Seven feet is generally enough in wooded or tight landscaped ground, where a deer will not commit to a jump it cannot see the landing for. A small enclosure — a vegetable garden, a fruit tree, a raised bed cluster, anything under roughly 150 feet of perimeter — can work at six feet, because deer will not jump into a space they judge too small to escape from. That is the trick worth knowing: a well-placed six-foot enclosure around the beds often beats an eight-foot perimeter around the whole property, at a fraction of the cost.

There is a local specific here that matters for budget. San Juan County exempts fences not over eight feet in height from needing a building permit — the county has adopted an amendment to the standard permit-exempt list raising the threshold to eight feet, well above the six or seven feet in the base code (SJCC 15.04). So the height that actually excludes deer is also, conveniently, right at the ceiling of what you can build without a building permit. That is not a blanket exemption from everything: shoreline jurisdiction, critical areas, setbacks, view easements, and any HOA or covenant rules still apply, and it is worth confirming with San Juan County Community Development before we set posts near a shoreline or a property line. I will tell you when I think a call is warranted.

Mesh versus wire is the other real choice. Black polypropylene deer mesh strung on posts is the cheapest per foot, effectively disappears at twenty feet, and is the right answer for a long wooded perimeter where you do not want to look at the fence. It will not stop a dog or a determined raccoon, and it needs its bottom edge properly staked or it gets pushed under. Welded or woven wire is stronger, holds a shape, and is what I would use anywhere it is visible, anywhere livestock or dogs are involved, and on the bottom three feet of a taller fence. A common and sensible build is welded wire on the lower half with mesh or tensioned line above it: strength where things push, invisibility where deer look for a top.

Almost every deer fence failure I get called to fix is at the bottom or at a gate, not at the top. Deer go under before they go over. On the uneven, rocky ground common here the fence line rides over ledge and dips through swales, and every gap becomes a door. That means staking the bottom edge continuously, running a ground-level tension wire, and filling the low spots with a skirt of wire rather than hoping. Gates need to be built to close by themselves and latch positively, because a gate propped open in July is the entire reason the fence was built. I hang gates with adjustable hinges, a self-closing spring or a drop-rod, and a latch that works with your hands full of a hose or a harvest basket.

For orchards and single specimen trees, a full enclosure is often overkill: a wire cage around each trunk plus a taller cage on the leader through the vulnerable years does the job, and can be moved as trees establish. For raised beds, a hinged top panel is worth building in from the start so you are not reaching over five feet of mesh to weed. I would rather design for how you actually use the space than build the tallest thing possible.

Where a fence is fighting existing structures — a driveway crossing, a deck, an existing sagging farm fence — those junctions are the work. Tying new deer fence into an old field fence properly, and getting a vehicle gate to stay square on sloping ground, is where most of the skill sits.