Spiking trees refers to climbing them using gaffs, which are sharp metal spikes strapped to your boots that dig into the bark as you ascend. It’s a core skill for arborists removing trees and for utility workers climbing poles. The technique requires proper equipment fitting, correct body positioning, and an understanding of when spikes are appropriate, since they do wound the tree.
How Tree Climbing Spikes Work
Tree climbing spikes (also called gaffs, spurs, or climbers) consist of a metal shank that straps to your lower leg, with a pointed spike extending from the inner side of your boot. You kick the spike into the bark at an angle, stand up on it, then advance the opposite foot higher. A lanyard or flip line wraps around the tree and clips to your climbing saddle, keeping you secured to the trunk at all times.
The technique looks simple but demands practice. You set each gaff at roughly a 45-degree angle to the trunk, keep your knees bent, and maintain your feet about shoulder-width apart. Small, deliberate steps work far better than ambitious lunges. The lanyard stays above your knees at all times, and you reposition it upward as you climb. Rushing or overreaching is how climbers “kick out,” where one gaff pops free and you slide down the trunk.
Choosing the Right Gaff Length
Not all spikes are the same length, and using the wrong size for the tree you’re climbing is both inefficient and dangerous.
- Tree gaffs are the longest, typically 2 3/4 inches or more. The extra length penetrates thick bark on species like firs, ponderosa pines, and redwoods to reach solid trunk wood beneath.
- Pole gaffs are shorter, usually 1 1/2 to 1 3/4 inches. They’re designed for utility poles but also work well on thin-barked hardwoods and palm trees.
- Hybrid gaffs split the difference at about 2 1/4 inches. These are the most versatile option if you’re working on a variety of trees.
If the gaff is too short for thick bark, it won’t reach solid wood and you’ll kick out. If it’s too long for thin bark, it can punch straight through and make the tree harder to climb safely.
Fitting Your Spikes Properly
Before you leave the ground, the fit has to be right. Position the shank so it sits about two finger-widths below your knee. The stirrup at the bottom should sit just in front of your heel, not under the arch of your foot. Tighten both the upper and lower straps until the spike feels like an extension of your leg rather than something flopping around on it.
A loose spike shifts under load, which means your gaff enters the wood at an unpredictable angle. That’s one of the most common causes of kickouts for beginners. Spend a few extra minutes on the ground getting the fit dialed in.
Step-by-Step Climbing Technique
Start by attaching your lanyard around the tree and clipping both ends to your climbing saddle. Lean back slightly so the lanyard bears some of your weight against the trunk. Kick your first gaff into the bark at a 45-degree angle, stand up on it, then set the second gaff slightly higher. Keep your knees bent throughout.
As you gain height, flip the lanyard upward in small increments. Never let it drop below your knees. Each step should be short, only about 6 to 12 inches. Longer steps force you into an awkward upright posture that reduces your leverage and makes it easier to pop a gaff loose. Think of it as walking up the tree, not leaping up it.
For descent, many arborists prefer switching to a climbing line rather than descending on spikes alone. Coming down is where fatigue causes mistakes. If you’re descending on spikes, reverse the process with the same small, controlled steps and keep the lanyard taut against the trunk.
When Spikes Should and Shouldn’t Be Used
This is where professionals draw a hard line. Climbing spikes pierce through bark and puncture the cambium layer, which is the thin band of living tissue that transports water and nutrients and protects the inner wood from disease and decay. Every spike hole creates a potential entry point for pathogens and wood-boring insects. While healthy trees can usually seal over spike wounds, the damage is unnecessary if the tree is staying.
The professional standard is straightforward: spikes are for tree removals only. If you’re pruning, inspecting, or doing any work on a tree that will continue to live, skilled arborists use rope-and-saddle climbing systems or aerial lifts instead. A responsible arborist would only spike a living tree in extraordinary circumstances, such as an emergency rescue.
If someone shows up to prune your trees wearing spikes, that’s a red flag. It signals either a lack of proper training or a lack of concern for tree health.
Keeping Your Gaffs Sharp
Dull gaffs don’t grip well, which means more effort and more risk of kicking out. But the goal isn’t a needle-sharp point. Overly sharp tips can snap off inside hardwood or penetrate too deeply, making it difficult to extract your foot.
The standard method is to file a flat edge on the top side of the gaff, then work each side evenly until they meet at a central point. A small grinding disc or a hand file both work. The key is maintaining that flat on the back side of the gaff. You want a chisel-like profile, not a sewing needle. Check your gaffs before every climb, since a single day on rough bark can dull them noticeably.
Fertilizer Spikes for Trees
If you searched “how to spike trees” looking for fertilizer spikes rather than climbing spikes, the process is much simpler. Fertilizer spikes are compressed sticks of slow-release nutrients that you hammer into the soil around a tree’s drip line, the circle on the ground directly below the outermost reach of the branches. Rain and condensation naturally fall along this line, dissolving the fertilizer and directing root growth toward it.
Place the spikes in soft, damp soil for best absorption. The number you need depends on trunk diameter measured straight across (not the circumference). Most packaging calls for one spike per every two inches of trunk diameter. So a tree measuring 10 inches across would get five spikes, spaced evenly around the drip line. Fertilizer spikes typically only need to be applied once or twice per year, making them one of the lowest-maintenance feeding options available.