Comparison: Best Harvest Organic Potting Mix (Updated | Nov 11th)

Back to the Roots uses a peat‑free blend of upcycled plant matter, wood fines, yucca extract for moisture control and dolomitic limestone for pH balance, while Miracle‑Gro relies on responsibly sourced sphagnum peat moss, coir and a quick‑release natural fertilizer. The Back to the Roots mix also adds mycorrhizal fungi to boost root development, whereas Miracle‑Gro focuses on a balanced fertilizer that feeds plants for up to two months. Both are organic, but the former emphasizes a lower carbon footprint and pest‑resistant formulation.

Peat extraction releases stored carbon, so mixes that contain peat—like most Miracle‑Gro products—have a higher greenhouse‑gas footprint than peat‑free options such as Back to the Roots. Miracle‑Gro mitigates this by using peat sourced from certified sustainable producers, but it still isn’t carbon‑neutral. If minimizing environmental impact is a priority, a peat‑free blend is the greener choice.

Back to the Roots indoor potting mix includes organic yucca extract, which helps retain moisture while preventing waterlogging, and dolomitic limestone that stabilizes pH for consistent water uptake. Miracle‑Gro’s indoor mix uses coir and peat, which also hold water well, but it does not have the added yucca technology. For the most precise moisture management, the Back to the Roots formula is generally superior.

Miracle‑Gro’s outdoor bundles provide the highest volume per purchase: the two‑bag 16‑qt pack (32 qt total) and the single 25‑qt bag both fill multiple 10‑ to 12‑inch containers and include a quick‑release fertilizer that lasts about two months. Back to the Roots offers a 12‑qt bag, which is suitable for smaller projects but requires buying more bags for large beds. Therefore, Miracle‑Gro’s larger packs deliver better cost‑per‑cubic‑foot value for extensive outdoor planting.

Miracle‑Gro’s outdoor and indoor mixes contain a quick‑release natural fertilizer that typically feeds plants for up to eight weeks before a top‑up is needed. Back to the Roots relies on a balanced blend of organic matter and mycorrhizae rather than a synthetic feed, offering steady nutrient availability without a defined expiration period. Espoma and Wakefield also include organic amendments like kelp meal, alfalfa, and biochar that release nutrients slowly over the growing season.

Both Back to the Roots indoor mix and Miracle‑Gro indoor mix are marketed for seed starting; they are lightweight, sterile, and contain enough organic matter to support germination. The presence of mycorrhizal fungi in Back to the Roots can give seedlings an early root‑boost, while Miracle‑Gro’s quick‑release fertilizer can provide an initial nutrient surge. Either product will work, but Back to the Roots adds the extra benefit of microbial support.

Back to the Roots sells 12‑qt value packs for indoor and outdoor use, typically priced lower per quart than Miracle‑Gro’s 16‑qt bags, but the latter offers larger bulk options (32 qt and 25 qt) that lower the cost per unit for big projects. Espoma’s all‑natural mix is sold in a 4‑qt container, making it a pricier choice for small‑scale gardeners. Wakefield’s premium biochar blend is positioned as a premium product, often costing more per quart but delivering added soil‑conditioning benefits.

Yes—Back to the Roots indoor mix includes mycorrhizal fungi to enhance nutrient uptake, and Wakefield’s premium blend adds biochar and humic acid for improved soil structure and microbial activity. Espoma’s formula also features a proprietary myco‑tone blend of endo‑ and ecto‑mycorrhizae. These additions can lead to stronger root systems and better long‑term fertility compared to standard organic mixes.