Deer deterrence

The number that decides everything

Extension services are unusually consistent here, and unusually blunt. Michigan State University Extension states that perimeter fences need to be at least 8 to 10 feet tall to be effective, and that the only sure deer barriers are woven wire fences or walls at least 10 feet tall. Penn State Extension notes that deer are capable of jumping an 8 ft fence and suggests considering 10 to 12 ft.

That is worth sitting with, because almost every polypropylene deer fence sold online is 7.5 ft. The ones on this site are 7.5 ft. They are a compromise, they are usually an effective one on sloping or wooded ground where a deer cannot see a clean landing, and they are the wrong product for flat open ground under heavy browse pressure. We would rather tell you that than sell you a fence that fails in March.

What each method is actually for

• Fencing is exclusion. It is the only method that works while you are not thinking about it, and the only one whose effectiveness does not decay. It is also the most work and the most visible. Deer fencing covers the products and the height trade-off.
• Repellents are mitigation. They reduce browse on treated foliage for as long as they are on the plant, which is until it rains, until the plant puts out new growth, or until the deer habituate. Used on a schedule they genuinely work; used once they do not. Best deer repellents has the picks.
• Devices are startle. A motion-activated sprinkler works on an approach that deer use repeatedly, and stops working when it freezes. Deer deterrent devices is honest about which of these have a published mechanism and which do not.

The useful framing is that these are not competitors. A fence handles the perimeter, a repellent handles the ornamentals you did not fence, and a sprinkler handles the one gate you keep leaving open. Spray vs fence vs device is the direct comparison.

Why repellents get a bad reputation

Almost always because of reapplication. A repellent is a coating; a coating on a growing plant covers a shrinking fraction of it every week. New leaves are untreated leaves. Rain strips product. And deer are perfectly capable of eating something they dislike if they are hungry enough and the alternative is nothing.

So the honest advice is: buy the concentrate rather than the ready-to-use bottle, because cost per treated area is what determines whether you keep spraying; put it on a calendar; and rotate products with different bases so habituation has less to work with. Plantskydd is blood-meal based and Bobbex is a different formulation, which is what makes rotating them meaningful rather than cosmetic.

Plant choice is the free half of this

Nothing on this page is as cost-effective as not planting the thing deer prefer. Colorado State University Extension publishes deer-resistant plant lists, and while nothing is deer-proof under enough pressure, moving the most-browsed species out of the front line reduces how hard every other method has to work. Keeping deer out of the garden covers this alongside the physical methods.

What we are not going to tell you

We have not installed any of these fences and we have not run a repellent trial. What we have done is compile the published specifications — heights, breaking loads, stated life expectancies, mixing ratios — and put them beside what the extension services publish about what actually excludes a deer. That is a real piece of work and it is checkable. How we pick sets out exactly where the line is.