These Are the Best Potting Soils for Indoor and Outdoor Plants, According to an Expert

Head to the nursery and you’ll find an array of potting soils for every imaginable gardening need from vegetable gardens to repotting your houseplants. However, there’s generally no need to purchase specialized potting soils for every type of plant. “Potting mixes are more or less interchangeable,” says Linda Chalker-Scott, PhD, professor and extension urban horticulturalist at Washington State University. “They also don’t need all those additives such as bio-stimulants and microbial inoculants.” If you’re concerned about sustainability, look for those that don’t contain ingredients such as peat and kelp, which may not be sustainably harvested.

On the other hand, some plants do benefit from specific soil types. “The media should reflect the natural habitat of the plant,” says Chalker-Scott. “For example, succulents and cacti do best in a coarse, sandy soil, while orchids that grow in trees do best in a rough, woody medium.”

When shopping locally, avoid buying bags that are saturated with water. Wet bags may compact and lose air spaces, which roots need to “breathe.” Soggy potting media also may release excess fertilizer (if the bag is labeled as continuous feed, controlled release or slow release), which can harm your baby plants.

Also, here's some good news if you’re thrifty: You can reuse old potting soil from previous year’s pots. “After old potting media has sat around for a while, it becomes compost,” says Chalker-Scott. “It doesn’t need any special treatment to ‘revive’ it. The material is still biologically active, with microbes freeing up nutrients as they decompose the material.”

The only exception: Don’t bring outdoor potting soil indoors because it may contain insect eggs, which can hatch once inside your home (yeah, definitely not something you want!), says Chalker-Scott.

Ahead, our top picks for the best potting soils for indoor and outdoor plants.