Comparison: Best Kellogg All Natural Potting Mix (Updated | Nov 11th)

Miracle‑Gro’s mix is a peat‑based formula that includes a quick‑release natural fertilizer to feed plants for up to two months, while Espoma relies on a blend of peat, humus, perlite, and organic meals enriched with mycorrhizae but contains no added fertilizer. The Miracle‑Gro product is marketed primarily for outdoor containers, whereas Espoma is labeled for both indoor and outdoor use and emphasizes a completely natural ingredient list. Choosing between them depends on whether you prefer an immediate nutrient boost (Miracle‑Gro) or a soil that builds long‑term soil health through beneficial microbes (Espoma).

The fertilizer is embedded in the peat matrix and dissolves gradually as you water the plants, providing a steady supply of nutrients for about 60 days. This reduces the need for separate feeding schedules during the early growing season. However, once the nutrients are exhausted, you’ll need to supplement with additional fertilizer or replace the mix for continued vigor.

Mycorrhizae are beneficial fungi that form a symbiotic relationship with plant roots, improving water and nutrient uptake, especially phosphorus. Espoma’s proprietary Myco‑Tone blend includes both endo‑ and ecto‑mycorrhizae, which can enhance root development and increase overall plant resilience. The effect is most noticeable over time, as the fungi colonize the root zone and work continuously.

For Miracle‑Gro, the 25‑qt bag fills roughly three 10‑inch containers, offering a lower cost per container than the 16‑qt bag, which fills one 12‑inch pot. Espoma’s 4‑qt seed starter is ideal for germination but not cost‑effective for larger containers. The 18‑qt and 29‑qt coconut‑coir mixes provide a good balance of volume and price for indoor or mixed‑use gardeners, especially when you need a lightweight, well‑draining medium.

The seed starter mix is formulated for optimal germination with a fine texture, high moisture retention, and balanced pH, making it excellent for the first few weeks of growth. When transplanting, you can blend it with a coarser potting mix (such as the 18‑qt or 29‑qt coconut‑coir blends) to improve drainage and aeration. Using a 50/50 mix helps seedlings adjust without shock while still benefiting from the starter’s nutrient profile.

Coconut coir retains moisture similarly to peat but offers superior aeration and a more neutral pH, reducing the risk of acid‑related nutrient lockout. The coir mixes also contain perlite, vermiculite, and rice‑hull charcoal, which further enhance drainage and prevent waterlogging. Peat‑based mixes like Miracle‑Gro provide excellent water holding capacity but can become compacted over time, requiring occasional loosening.

Yes, the product states that 100 % of its peat comes from certified producers who follow sustainable harvesting guidelines. This certification helps mitigate the environmental impact associated with peat extraction. However, consumers seeking peat‑free options may prefer coir‑based blends such as the 18‑qt or 29‑qt mixes.

Both mixes are versatile and can be used outdoors; their balanced blend of coir, peat, perlite, vermiculite, and charcoal provides good drainage and moisture retention for a wide range of plants. For heavy‑feeding outdoor vegetables, you may want to supplement with an organic fertilizer, as these mixes do not contain built‑in nutrients like Miracle‑Gro’s formula. Ensure the containers have adequate drainage holes to prevent root rot.