Comparison: Best Outdoor Soil For Indoor Plants (Updated | Nov 11th)

Miracle-Gro Moisture Control Potting Mix is designed with an AquaCoir formula that absorbs up to 33% more water than basic soils, helping prevent both over‑ and under‑watering. Its moisture‑retaining properties make it ideal for indoor plants that prefer a steady supply of water, such as pothos or spider plants. The mix also includes a built‑in fertilizer that feeds plants for up to six months.

The Moisture Control version adds the AquaCoir technology, which boosts water retention and reduces the risk of root rot, while the regular mix relies on a traditional peat‑based blend. Both products feed plants for up to six months and claim to grow plants twice as big, but the Moisture Control mix also helps maintain more even moisture levels. The regular mix is slightly cheaper per bag but may require more careful watering.

Organic mixes such as Wonder Soil and Miracle‑Gro Organic Indoor Potting Mix provide natural amendments like worm castings, kelp, and mycorrhizae, which can improve root development and long‑term soil health. They are peat‑free or use responsibly sourced peat, making them a greener choice for eco‑conscious gardeners. While they cost a bit more, the added nutrients and reduced chemical inputs often translate to healthier plants and less frequent fertilizing.

Coco coir offers excellent water retention while providing superior drainage and aeration, which helps prevent root suffocation. Wonder Soil’s compressed format expands four times its size, saving storage space and making it lightweight to transport. Additionally, coco coir is a renewable resource, so it’s a more sustainable alternative to peat‑based blends.

Most manufacturers recommend filling an 8‑inch pot about one‑third full with potting mix, placing the plant, then topping off the remaining space. A single 4‑qt bag of Miracle‑Gro Houseplant Potting Mix or an 8‑qt bag of Wonder Soil typically fills one 8‑inch pot, while an 8‑qt bag of the standard Miracle‑Gro Potting Mix can fill two such pots. Always check the product’s coverage guidelines for the most accurate estimate.

The two‑bag bundle of Miracle‑Gro Moisture Control Potting Mix (2 × 8 qt) provides a good balance of price, moisture management, and built‑in fertilizer, covering multiple 8‑inch containers. For larger projects, the 2 × 16 qt bundle of regular Miracle‑Gro Potting Mix delivers the lowest cost per cubic foot, though it lacks the extra moisture‑control technology. If you prioritize organic ingredients, Wonder Soil’s compressed 4‑qt bag expands to fill several pots, offering solid value for its nutrient‑rich formula.

Miracle‑Gro mixes contain a synthetic, quick‑release fertilizer that feeds plants for up to six months, giving rapid growth and vivid blooms. Organic mixes like Miracle‑Gro Organic Indoor Potting Mix and Wonder Soil use natural fertilizers and amendments that release nutrients more slowly, supporting steady, long‑term health. Synthetic blends often produce faster results, while organic options are gentler on the environment and reduce the risk of nutrient burn.

Michigan Peat’s general‑purpose blend works for both indoor and outdoor applications, but it lacks the moisture‑control additives found in specialized indoor mixes. It provides good drainage and moderate water retention, making it suitable for hardy indoor plants that tolerate a drier root zone. For more moisture‑sensitive houseplants, a mix with added perlite or coco coir, such as Miracle‑Gro Moisture Control or Wonder Soil, may deliver better results.