Pendelton Turf Supply 18-3-6 Liquid Fertilizer (50% SRN & Mi

The Verdict

Bottom line up front: The Pendelton Turf Supply 18-3-6 is a serious liquid fertilizer for homeowners who want granular-level feeding duration with liquid application flexibility. The 50% slow-release nitrogen (SRN) is the headline feature here — it bridges the gap between cheap quick-release liquids that green your lawn for ten days and expensive granular programs. At 4.4 stars across 220 ratings, most users find it delivers. But it’s not perfect, and I’ll tell you exactly where it gets sticky.

What’s actually in the jug

You’re getting a 2.5-gallon concentrate with an 18-3-6 NPK ratio. That’s 18% nitrogen (half of it slow-release), 3% phosphate, and 6% potassium. The micronutrient package — iron, manganese, and zinc — is what separates this from the big-box store blue liquids. As shown in the product image, the jug includes a measuring cap, but you’ll want a separate sprayer since this is a concentrate, not a hose-end ready formula.

One jug mixed at the standard 4 oz per 1,000 sq ft rate covers roughly 20,000 square feet. That’s a quarter-acre lawn from a single purchase, which puts the per-treatment cost well below what you’d pay for Scott’s or Miracle-Gro equivalents.

How it performs in real use

I’ve seen enough fertilizer reviews to know that “slow-release liquid” is often marketing fluff. This one isn’t. The 50% SRN comes from methylene urea, which breaks down over 6-8 weeks rather than dumping all at once. Users consistently report visible darkening within a week — that’s the iron working, not just nitrogen.

One verified buyer noted: “Applied mid-May, didn’t need to reapply until early July. My lawn stayed green through a dry stretch where my neighbor’s fertilizer went dormant.” That tracks with the chemistry. The slow-release portion keeps feeding while the quick-release gives you that initial pop.

The liquid format is genuinely better for spot treatments. You can dial in thin patches or overseeded areas without blanketing the whole yard. It mixes cleanly with water and doesn’t clog sprayer nozzles — a common complaint with cheaper suspensions.

Where it falls short

First, the sediment problem. This is a thick concentrate, and the micronutrients settle hard between uses. Multiple reviewers mention needing to shake the jug aggressively — like, really shake it — before every application. If you skip this, the first half of your tank gets the nutrients and the last half gets mostly water.

Second, this is synthetic. If you’re running an organic program or have kids/pets that roll around on the lawn constantly, the salt index is higher than natural options. You can manage it by watering in after application and rotating with compost top-dressing, but it’s worth knowing.

Third, the measuring cap is small for a 2.5-gallon jug. You’ll be refilling it multiple times for larger lawns, which gets tedious. Some users recommend buying a cheap graduated cup separately.

Who should buy this

Buy it if: You have a 5,000-20,000 sq ft lawn, want liquid application convenience, and are tired of reapplying every two weeks with standard liquid fertilizers. Also good if you’re establishing new seed and need gentle, consistent feeding.

Skip it if: You’re strictly organic, have a tiny postage-stamp lawn where a hose-end bottle makes more sense, or you’re not willing to shake the jug properly before each use.

FAQ

Q: How often should I apply this? Every 6-8 weeks during the growing season. Three applications cover a typical spring-to-fall window. Don’t stack applications — the slow-release nitrogen is still working.

Q: Can I use this on new sod or seed? Yes, but wait until the second mowing. The quick-release nitrogen can stress tender new growth if applied too early.

Q: Does it need to be watered in? Ideally yes, especially if temps are above 80°F. Watering within 24 hours moves the nutrients into the root zone and prevents any potential leaf burn.

The Verdict: 4.2/5

Buy it if you want a liquid fertilizer that actually lasts more than two weeks and don’t mind shaking a jug before each use. Skip it if you need organic certification or want a set-and-forget granular program. This is a solid mid-tier product that outperforms its price point — the slow-release technology and micronutrient package justify the purchase for anyone serious about lawn color without babysitting a sprayer every weekend.

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.