SimplyGro Fertilizer Spikes for Evergreen Trees & Shrubs

The Verdict

Let me be blunt: most fertilizer spikes are overpriced convenience items that barely outperform a bag of generic 10-10-10. The SimplyGro Evergreen Spikes are different — but they’re also not magic. After digging through 229 ratings and what actual buyers are saying, here’s the real story.

What You’re Actually Getting

The box contains pre-formed spikes with a 10-10-10 NPK ratio — nitrogen, phosphorus, and potassium in equal parts. That’s a balanced maintenance formula, not a growth booster. Each spike is designed to feed continuously for up to six weeks, which means roughly two applications per growing season. As shown in the product image, spikes come in a resealable bag, which matters more than you’d think — moisture ruins these things if left exposed.

The spike format solves the two biggest problems with granular fertilizer: drifting (where wind blows your powder into the neighbor’s yard) and measuring errors. You don’t need a spreader, gloves, or a scale. You count spikes based on trunk diameter, hammer them into the soil around the drip line, and you’re done.

Performance: What Buyers Actually Report

The most consistent praise centers on how easy these are to use. One verified buyer put it plainly: “I have 12 arborvitae and this took me 20 minutes total. No mess, no smell, and the trees greened up noticeably within a month.” That tracks with the slow-release design — the nutrient release is driven by soil moisture and temperature, so you’re not getting a quick green-up like you would with liquid feed, but you’re also not getting the burn risk.

Another reviewer noted something useful: “Used on boxwoods that were struggling after a rough winter. New growth appeared within 3 weeks. Will buy again.” That suggests the spikes do deliver micronutrients through the root zone effectively, even on stressed plants.

Where It Falls Short

Here’s the honest downside: soil prep matters. If you have heavy clay or compacted ground — common around established trees — you’ll need to pre-drill holes with a screwdriver or auger. One frustrated reviewer wrote: “Bent two screwdrivers trying to get these into the ground. Should have read the directions more carefully.” The instructions do say to moisten the soil first, but that’s easy to miss when you’re in a hurry.

Also, this is a maintenance formula, not a rescue treatment. If your tree is showing serious nutrient deficiency — yellowing between veins, stunted growth — you need a soil test and possibly a targeted supplement. These spikes will maintain health but won’t fix a severe imbalance.

Who Should Buy This

This is perfect for the homeowner with 5-20 trees or shrubs who wants set-and-forget feeding. No measuring, no spreader, no chemical smell. It’s also great for anyone who’s burned plants before with liquid fertilizer — the slow-release format is forgiving. Skip it if you’re a serious gardener managing a large orchard or dealing with diagnosed nutrient deficiencies. You need granular control, not convenience.

FAQ: What Shoppers Ask

How many spikes do I need per tree? The label recommends 1 spike per 2 inches of trunk diameter, measured at chest height. For a typical 6-foot arborvitae, that’s usually 2-3 spikes. For a mature oak, you’re looking at 15-20.

When should I apply these? Early spring, just as new growth begins, and again in late summer. Don’t fertilize in fall — you’ll encourage tender new growth that winter will kill.

Are these safe around pets and kids? Once worked into the soil, the spikes are largely inert. The main risk is if a pet digs them up and chews on them — the fertilizer itself can cause stomach upset. Bury them fully and mark the area.

The Verdict

Buy it if: You want a foolproof, low-effort way to keep established evergreens and shrubs healthy. The convenience premium is worth it for anyone who’s ever wrestled with a 50-pound bag of granules.

Skip it if: You have heavy clay soil you’re not willing to pre-drill, or you’re trying to fix a severe nutrient deficiency rather than maintain health.

The 4.6-star rating holds up. This is a solid, well-executed product that does exactly what it claims — just make sure you read the soil preparation notes before you start hammering.

Rating: 4.6/5

Where to Buy

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