The Old Farmer's Almanac Tree & Shrub Fertilizer Spikes (Box

The Verdict

If you’ve ever wrestled with a 50-pound bag of granular fertilizer, trying to calculate the right spread rate while it blows into your face, you’ll appreciate what The Old Farmer’s Almanac Tree & Shrub Fertilizer Spikes offer: simplicity. This box contains 24 pre-measured spikes that deliver a season’s worth of nutrients directly to the root zone. No mixing, no spreader, no guesswork. It’s the lazy gardener’s dream — and honestly, that’s a compliment.

What’s Actually in the Box

You get 24 brown, chalky spikes roughly the size of a fat crayon. Each one weighs about 1.5 ounces. The formulation is a 15-5-10 NPK ratio with added micronutrients — that’s higher nitrogen for foliage growth, moderate phosphorus for root development, and potassium for overall vigor.

The packaging claims each spike feeds for 6-8 weeks, and the math checks out: with 24 spikes, you’re covering one application for a mature tree (using 4-6 spikes per tree depending on trunk diameter) or two rounds for smaller shrubs. The spikes are designed to be hammered into moist soil around the drip line — that’s the circle where rain falls from the outermost branches.

How It Performs in Real-World Use

Here’s where the spikes separate themselves from powder fertilizers. Because they’re placed directly in the root zone, there’s zero runoff. The nutrients don’t wash away with the first rainstorm. For anyone living near waterways or dealing with heavy rainfall, this is a genuine environmental plus.

The slow-release mechanism works — but it works slowly. Multiple buyers on Amazon note that “it took about a month before I noticed the leaves getting darker and denser.” One verified reviewer wrote, “The arborvitae were looking scraggly in early spring. By mid-summer, there was visible new growth and a richer green.” Another customer applying them to a young maple said, “The tree put on noticeably more height than the previous year.”

Installation is the catch. These spikes are dense, and you’ll need to hammer them flush with the soil surface. In hard, compacted clay — common in new subdivisions — you’ll want to water the ground thoroughly a day before, or use a steel rod to pilot holes first. One frustrated reviewer admitted, “Bent two screwdrivers trying to get these into rocky soil.” That’s a fair warning, not a dealbreaker.

What Buyers Consistently Praise

The 4.7-star rating across 235 reviews isn’t accidental. Three themes dominate the positive feedback.

First, ease of use — “No measuring, no mess, just drive them in and walk away.” Second, effectiveness on problem trees — multiple reviewers report reviving yellowing leaves on established maples, oaks, and fruit trees. Third, value — at roughly 50 cents per spike, this is significantly cheaper than liquid fertilizer applications or hiring a tree service.

Where It Falls Short

Let’s be direct about the limitations. These spikes won’t fix a tree that’s already struggling from disease, poor drainage, or root damage. They’re a feeding tool, not a rescue remedy.

The spike format also means nutrients concentrate in specific spots rather than spreading evenly. For trees with extensive root systems, you’d need to space spikes carefully — the instructions call for placing them at least 3 feet apart in a grid pattern, which means larger trees can require most of the box.

And the 15-5-10 ratio leans leaf-heavy. If your primary concern is fruit production rather than foliage, you’d want a bloom-boosting formula instead. This is a general-purpose feed, not a specialized one.

Who Should Buy This

Buy it if you have established trees or shrubs (2+ years in the ground) that need a reliable annual feeding without the hassle of measuring granules. It’s ideal for homeowners who want a “set and forget” approach — one spring application covers the entire growing season.

Skip it if you’re planting new saplings, growing in containers, or dealing with rocky soil that makes hammering spikes impractical. You’d be better served by a liquid fertilizer or a top-dressing of compost.

FAQ: Three Questions Shoppers Actually Ask

Q: How many spikes does a tree need?
Measure trunk diameter at chest height. For every 2 inches of diameter, use 2 spikes. A 6-inch trunk needs 6 spikes, hammered in a ring around the drip line. This is covered in the included instructions, which are refreshingly clear.

Q: Can I use these on fruit trees?
Yes, and many reviewers do. The 15-5-10 ratio supports both leaf and root growth, which helps the tree build energy for flowering. Just don’t expect them to replace a dedicated fruit-tree formula with a higher middle number.

Q: When should I apply them?
Early spring, just as buds begin to swell, is ideal. You can also apply in late fall after leaf drop for a slow winter release. Avoid midsummer application during drought stress — the tree won’t be able to take up nutrients effectively.

The Verdict

Rating: 4.6/5 — The Old Farmer’s Almanac Tree & Shrub Fertilizer Spikes deliver exactly what they promise: a no-mess, season-long feeding with visible results. They’re not the most precise tool for specialized needs, and installation in hard soil requires some elbow grease, but for the typical homeowner with a handful of established trees and shrubs, this box is a solid investment.

Buy it if you want to stop guessing with fertilizer measurements and start seeing greener, healthier trees with one spring-time application.

Skip it if you’re working with young transplants, containers, or heavy clay that resists hammering — you’ll find liquid or granular options easier to manage.

Where to Buy

👉 Check Price on Amazon →

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Last updated: 2026-08-06. Ratings and prices current as of review date. Verify on Amazon before purchasing.