Great Big Roses Natural Compost Extract Fertilizer

The Verdict

The Short Version: If you want bigger, more abundant rose blooms without dumping synthetic chemicals on your garden, Great Big Roses Natural Compost Extract is worth serious consideration. This isn’t a magic potion — it’s a biologically rich compost tea concentrate that feeds the soil so your roses can feed themselves. At 4.6 stars across 229 ratings, it’s one of the better-reviewed organic rose amendments on Amazon.

What You Actually Get

The product arrives as a concentrated liquid in a standard garden-sized bottle. As shown in the product image, it’s a dark, earthy liquid that smells exactly like what it is: composted manure extract. The mixing ratio is straightforward — 2 ounces per gallon of water — and you can apply it as a soil drench or foliar spray. One bottle typically covers 10–15 mature rose bushes per season, depending on how often you feed (most buyers apply every 2–4 weeks during the growing season).

How It Performs in Real Gardens

Here’s what the chemistry actually does: this isn’t an NPK fertilizer in the traditional sense. It’s a compost extract, meaning it’s packed with beneficial microbes, humic acids, and trace nutrients that improve soil structure and nutrient availability. Your roses still need a balanced fertilizer for primary nutrients (nitrogen, phosphorus, potassium), but this product helps them use what’s already in your soil.

Buyer feedback backs this up. One verified purchaser noted: “I was skeptical, but after three weeks my Knockout roses had more buds than they’d ever produced. The color was deeper too.” Another gardener with container roses reported: “My potted roses were struggling with yellow leaves. Two applications later, they greened up and started blooming again.”

The most consistent praise centers on bloom size and quantity. Multiple reviewers describe “bigger flowers” and “more blooms per stem” after 2–3 applications. Container gardeners seem especially pleased — the microbial boost helps compensate for the limited soil biology in pots.

What Buyers Consistently Praise

• Visible results within weeks — most reviewers see improvements in 2–4 weeks, not months
• Gentle on plants — no burn risk even when applied at full strength to established roses
• Safe around pets and kids — once watered in, it’s biologically active but not toxic
• Works on more than roses — several buyers report success on hydrangeas, tomatoes, and other flowering perennials

Where It Falls Short

Let me be direct about the downsides, because there are a few.

The smell. This is the #1 complaint in negative reviews. It smells like fresh manure for the first 24 hours after application. If you’re applying near a patio or open windows, that’s a real consideration. The odor does dissipate, but it’s not pleasant while it lasts.

No measuring cap. The bottle has a simple cap, not a measuring one. You’ll need your own measuring spoon. Minor, but annoying.

It’s not a complete fertilizer. If your roses are already nutrient-deficient, this alone won’t fix them. You still need a balanced rose food. Think of this as a soil amendment that enhances your feeding program, not a replacement for it.

Bottle size is modest. For larger gardens (20+ bushes), you’ll need multiple bottles per season. Check the price per ounce before committing.

Who Should Buy This

• Organic gardeners who want to avoid synthetic chemicals but still want bigger blooms
• Container rose growers whose potted plants struggle with soil depletion
• Rose enthusiasts with established bushes that have plateaued in bloom production
• Gardeners dealing with poor or compacted soil who need a biological boost

Skip it if you’re looking for a complete, all-in-one fertilizer, or if you have a tiny balcony and can’t tolerate any manure odor near your living space.

FAQ

Q: How often should I apply it? A: Most successful users apply every 2–4 weeks during the active growing season (spring through early fall). Reduce frequency in extreme heat or during dormancy.

Q: Can I use it on other plants? A: Yes. Many buyers report success on hydrangeas, daylilies, tomatoes, and other flowering plants. Dilute as directed and test on one plant first.

Q: Does it really smell that bad? A: It smells like composted manure — think farmyard, not chemical. The odor fades within 24 hours, but it’s noticeable immediately after application. Watering it in helps reduce the smell faster.

The Verdict

Buy it if: You’re an organic gardener with established roses that need a biological boost, or if you’re growing roses in containers and struggling with soil quality. It’s a legitimately effective soil amendment with strong buyer consensus behind it.

Skip it if: You need a complete fertilizer, can’t tolerate any manure odor, or have a very tight budget — you’ll need to pair this with a balanced rose food.

Rating: 4.6/5 — Deducting half a star for the smell and the lack of a measuring cap. The results are real, the price is fair, and the organic approach is genuinely effective for improving bloom production.

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.