Comparison: Best Kellogg Organic Plus Potting Soil (Updated | Nov 11th)

Look for the base ingredients (peat, coco coir, or peat‑free blends) and how they affect moisture retention and drainage. Check if the mix includes added nutrients, such as natural fertilizers or mycorrhizal fungi, which can boost early growth. Also compare the intended use—indoor versus outdoor, container size, and the types of plants you plan to grow.

Peat provides excellent water‑holding capacity but has a higher environmental impact, while peat‑free blends such as coco coir or upcycled wood fines offer similar moisture control with a lighter carbon footprint. Peat‑free mixes often include additives like yucca extract or dolomitic limestone to balance pH. Performance is comparable for most houseplants and vegetables, so your choice may hinge on sustainability preferences.

The Miracle‑Gro Organic Outdoor Potting Mix sold in a 25 qt bag fills roughly three 10‑inch containers, providing a low cost per plant and includes a quick‑release natural fertilizer that feeds for up to two months. The Michigan Peat 40‑lb bag also offers a large volume and is ready‑to‑use, but it lacks the built‑in fertilizer, so you may need to add nutrients separately. For pure value, the larger Miracle‑Gro bag typically wins on price‑per‑cubic‑foot.

Back to the Roots 100 % Organic Indoor Potting Mix is formulated without bark or compost, reducing the risk of gnats and is labeled pet‑safe. The Organic Potting Soil for Indoor Plants also emphasizes a cruelty‑free, non‑GMO formula that is safe around animals. Both options avoid animal‑derived ingredients and synthetic chemicals, making them good choices for homes with pets.

Added natural fertilizers, like the quick‑release blends in Miracle‑Gro mixes, give seedlings a nutrient boost for the first few weeks, which can speed up establishment. Mycorrhizal fungi, found in products such as Espoma and Back to the Roots, enhance root development and improve nutrient uptake over the plant’s life cycle. While not essential, these additives can reduce the need for supplemental feeding and improve overall plant vigor.

Coco coir offers excellent water retention while providing superior aeration, helping prevent root rot in both indoor and outdoor settings. Wonder Soil’s blend also includes worm castings, kelp, and perlite, delivering a nutrient‑rich environment without peat’s higher acidity. For gardeners seeking a lightweight, peat‑free solution, coco coir mixes are a strong alternative.

Miracle‑Gro Organic Indoor Potting Mix is designed for seed starting, featuring a balanced blend of sphagnum peat, coir, and a gentle starter fertilizer that protects against over‑ and under‑watering. Back to the Roots Indoor Mix also includes yucca extract for moisture control, making it forgiving for young seedlings. Both provide a sterile, nutrient‑rich medium that encourages quick germination and healthy transplants.

Larger bags generally lower the cost per cubic foot; for example, the 40‑lb Michigan Peat bag and the 25‑qt Miracle‑Gro bag spread the price over many containers. Smaller 12‑qt bags, like the standard Miracle‑Gro Indoor mix, are convenient for hobbyists but have a higher per‑plant price. When budgeting, calculate the total volume each bag provides and compare it to the number of pots you plan to fill.