We evaluated the many potting soil products for their intended use, as well as their added ingredients, such as fertilizer, and other attributes such as water retention. Our top choice was Wonder Soil Organic for its unique blend of slow-release organic nutrients, sterility, and pet-friendly formula. Here are our top recommendations for the best indoor potting soil. Most potting soil for indoor plants contains the essential nutrients to give new greenery a good jump start, or transplants the food they need. Wonder Soil Premium Organic Potting Mix does this, adds more ingredients and more to help indoor plants thrive, and it can be used with just about any plant. All that earns this product our Best Overall selection. In addition to earthworm castings, kelp, and perlite, all of which provide indoor plants with the nutrients they need to grow their best, Wonder Soil also contains coco coir, commonly used as a bonus-type growth medium. We like the coco coir in this product because it expands, keeping plants moist for longer, meaning you need to water less frequently. The manufacturer claims that when mixed with water, the product expands from 3 pounds in the resealable bag to 12 quarts of indoor soil. The product also contains mycorrhizae—fungal roots which can help plants better ingest nutrients and may add protection against diseases that reside in soil. Wonder Soil also is pre-mixed with garden soil mix, so it’s a plant starter as well. To use Wonder Soil, which has a slow-release form of nitrogen, you just transplant the plant and add the product. You also can use it to start an indoor plant from seed. The manufacturer recommends only a third of a cup for a 4-inch pot. This mix also doubles as a seed starter. Despite the heaps of nutrients, the mix is lightweight and offers plenty of aeration, allowing for effective moisture retention. We also like that Foxfarm product support specialists can assist one-on-one with providing detailed information on each potting soil and suggest the best one for your plants. African violets are finicky about their pH, with the optimal range leaning towards the acidic side. Taking this into consideration, SunGro adds dolomite lime to naturally lower the pH of the soil. Espoma Organic Potting Mix also improves the overall soil structure and slowly feeds plants as it breaks down, rewarding you with healthy plants all season long. As an extra bonus, it is an excellent choice for hobby plant propagators, as it improves plant cuttings and transplants to thrive. This mix can also be used for seed starting, propagation, and any other plant project you dream up. The peat moss breaks down slowly, acting as a soil conditioner and providing food to your plants. This lightly textured, well-aerated product is formulated with an IBI certified biochar, which increases retention of nitrogen, phosphorus, and other nutrients. Biochars can improve soil fertility as well. The product’s aged bark blend adds additional pore space to the soil, allowing houseplants to use the limited resources of indoor environments. FoxFarm adds plenty of nutrients, including bat guano, that benefit your homegrown herbs. Included beneficial bacteria and fungi help break down nutrients into an easier form for plants to take up. This relationship boosts the health of the roots, creating stronger, healthier herbs with enhanced resistance to disease and pests. It should be noted that Happy Frog is too heavy to start seeds in and also is not a sterile mix. This product is also pH balanced, which is important since cacti and succulents prefer neutral soil environments. Hoffman also features clear, easy-to-follow directions for getting the most out of their mix. The 4-quart size might seem small at first, but a little goes a long way here.
Ingredients
“If you want to get more nitty gritty, you can keep in mind what type of plants you are potting,” says Erin Marino, Editorial Lead at The Sill. “Different plants may prefer different potting mix ingredients.” Ingredients vary across the indoor potting soil spectrum, with some being exceptionally light on variety, and others containing moisture-absorbing materials such as coconut coir or moss. Rich ingredients, including bat guano, sea minerals, humus, and earthworm castings, are ideal for heavy feeders, among them flowers, herbs, and vegetables. A plant’s native environment is a great indicator of their soil preference as well. “For example, a succulent plant like a snake plant or cactus will like a mix that is more porous, such as one that contains more perlite, that water can run through quickly and that will not hold moisture,” Marino adds. “On the other hand, plants native to more tropical and semi-tropical environments like ferns pay prefer a mix with more peat, since it helps the soil stay moist. So when looking for a potting mix, keep your plants’ natural habitats in mind. Does your plant call the dry desert or the tropical rainforest home? Special mixes have been developed for these different classes of plants."
Nutrients
Some plant potting mixes double as fertilizers. So instead of waiting for the soil to add nutrition as it slowly breaks down, these are available for plants to use when they need them. The tiny amounts of additional plant food included in soil blends is slow release, and carefully balanced to ensure that plants do not end up burned from over-fertilization. (You can recognize this by yellow “singe”-like edges against the foliage’s green background.) If using fertilizer makes you nervous, starting with quality soil helps reduce or eliminate the need for it.
Why Trust The Spruce?
This article was researched and written by Amanda Rose Newton, a freelance garden reviewer for The Spruce. As a horticulture professor, business owner, and entomologist, she delighted in personally testing out the recommended products to provide advice to those with unique needs, yards, and values when it comes to all things soil. Don’t forget that your plants also do well with a soil refresh. “Plants typically benefit from being repotted every 12 to 18 months, depending on how actively they are growing,” says Marino. “Some slow growers, like cacti, can call the same pot home for years but may require a potting mix replenishment (new potting mix or fertilizer to provide fresh nutrients - but not more space). The growing season, early spring through late summer, is usually the best time to repot your plants. Because your plants are actively growing during this time, they’ll get the most out of additional space and fresh nutrients.” To make this list, Amanda Rose tested each product on a fiddle leaf fig, monstera, dracaena, African violet, and jade plant. Over the course of a month, she monitored their growth, soil moisture retention, and overall condition of the plants before offering her suggestions on the best choices for the indoor plant enthusiast. Emma Phelps, an Updates Writer for The Spruce, provided additional support for this roundup by contacting Erin Marino, Editorial Lead at The Sill. Marino provided insight on typical soil ingredients to look out for, repotting techniques, and other houseplant care tips.
