Maintaining a fiddle leaf or orchid — both of which are notoriously fickle — often depends on how you prep the plant to survive when you pot it. Potting soil should have the right ingredients to aerate and provide nutrients for plants, which is why estate gardener and horticulturist Brooke Medlin says potting mixes are typically composed of peat, a little bit of shredded pine bark, and superheated minerals like perlite or vermiculite to aerate the soil. “Peat and perlite are really made for aeration, so they’re found in pretty much every potting mix you’re going to find,” she says.
A general potting soil mix will suit a variety of houseplants, though something more fussy like a succulent or orchid might require a more specific mix catered to its needs. Seasoned horticulturist Joyce Mast has over 40 years of experience in the field and oversees Bloomscape’s greenhouses. She says the most important things to keep in mind are a plant’s pH, porosity, and water-holding capacity. “pH, or acidity, is important because nutrients can be unavailable to the plant if the pH is out of an acceptable range,” she says, while porosity (the space between soil particles) can indicate the roots’ ability to access oxygen, and a plant’s water-holding capacity suggests whether they prefer a drier or wetter soil environment. Here, we talked to a handful of horticulturists and plant specialists to find out the best soils for every type of indoor plant.
Standard potting soil mixes
The horticulturists we spoke with were insistent that you don’t need to get too precious when choosing a general potting mix that will cater to a variety of plants. No one suggested anything prohibitively expensive, and they noted that you can find most things at your local Lowe’s, Home Depot, or gardening center. “When I’m taking care of somebody else’s plants, the Miracle Grow potting mix is great,” says Medlin. She uses it for both indoor and outdoor plants and “across the board for almost every plant that I take care of for my work” — including traditional house plants, seedlings, and even the occasional succulent. You can go higher end if you want, but she says that most potting mixes are about the same. “I’ve never had one that has caused my plants to die,” she adds.
If you’re confused about whether a standard potting soil mix will work for your plant, Medlin says you can generally go by the labels on the bags. When you’re at a store and don’t see your particular plant mentioned on a plant-specific mix, she recommends going with a regular potting soil mix. Here’s one that works for indoor and outdoor potted plants.
And an indoor-plant-specific potting mix from MiracleGro that Mast likes for its water retention, porosity, and pH-balancing properties. It uses coconut coir to retain moisture in the soil, and avoids pine bark, which can attract gnats in your apartment.
Mast also recommended this Espoma organic potting mix that’s designed for better water retention. It contains peat moss and perlite, plus some limestone to adjust the pH levels of the soil.
Horticulturist Angie Eckert, the vice president of retail operations at Eckert’s Farms — says she’s a “huge believer” in Fertilome Ultimate Potting Mix, which contains two types of limestone to balance out soil acidity. This mix works for a variety of plants like seedlings, indoor plants, and outdoor planters, she says, and because it’s very lightweight she notes that it doesn’t add any unnecessary weight to planters. “It’s very similar to potting mixes we used in outdoor planters at Longwood Gardens and the Missouri Botanical Gardens when I worked there.”
Soils for cacti and succulents
Cacti and succulents can be surprisingly hard to keep alive, which Eckert explains has to do with their water retention. “Succulent plants cannot tolerate ‘wet feet,’ also known as water-saturated potting mix around their root system,” she says, so she advises choosing potting mix that contains ingredients like peat moss and perlite to “hold moisture while allowing excess water to drain through the mix.” For cacti, “which can be top heavy,” she suggests a mixture with sand in it to add weight to the container and serve as a counterbalance to the plant. “Sand also helps drain excess water so the cacti are not being overwatered.”
Mast recommended this Miracle Gro potting soil for taking care of cacti and succulents. It contains sand, perlite, and peat, which Mitesh Popat — the CEO and co-founder of Hollywood fruit-tree gifting company Plant-O-Gram — says works wonders for all types of plants that are prone to waterlogging. “We can’t stress enough the importance of using a well-draining potting mix such as the Miracle Gro cactus mix. Cactus mix drains extremely well and will ensure that you cannot overwater your plant no matter how heavy-handed you are with watering.”
We’d be remiss not to mention the Black Gold cactus mix that Sprout Home uses for their cacti. It blends pumice, coco fiber, peat, and perlite, and according to their general manger Stephen Mills, “doesn’t compress like standard potting soil, so the roots of our plants can drink what they need and then dry out as soon as possible.”
Soils for orchids
Orchids are especially easy to kill since they have aerial roots which need a lot of drainage and fluffier, lighter soil, says Medlin. “They don’t like it to be super wet and dense.” She points out that monsteras are very similar since they have aerial roots, and says really anything with aerial roots will benefit from orchid soil — just make sure to repot them with fresh soil twice a year to avoid the soil getting compacted from the top. Mast recommends this organic potting soil that consists of light pine bark, charcoal to absorb leftover salt from fertilizers, spongey rock to offset the pH balance, and coconut chips to ensure the mix is airy enough for the roots to climb and expand.
For true orchid novices, David Horak — curator of the Aquatic House and Orchid Collection at the Brooklyn Botanic Garden — has recommended sphagnum moss mixes to us in the past because he says it’s easier to determine if the soil is wet or dry, and also “has a natural antiseptic quality,” to avoid root rot.
Here’s another custom-blended orchid mix that mostly consists of sphagnum moss which we’ve covered before – it’s hand-mixed by a company called rePotMe which specializes in orchid products.
You can also add fertilizer or plant food to the soil to promote growth and root health, and even to make your flowers bloom. Regularly using fertilizer is important because Mast says, “over time as a plant grows and is watered, the vital nutrients will be used up or flushed out of the soil and need to be replenished.” Medlin says you can use an all-purpose fertilizer like Miracle Gro, which she generally recommends doing once a month for indoor plants. You add a sprinkle of the fertilizer into your watering can when you’re watering your plants, she says, “so it’s super easy.”
But Mast notes that once-a-month treatments should really only happen during certain seasons. “We only recommend adding fertilizers spring through fall because most indoor plants go through a resting period during the winter and adding fertilizers will do more harm than good,” she says. Plants don’t require added food then, so any additional fertilizer will just settle in the soil and cause salt buildup.
Medlin really prefers to use a natural fertilizer called “vermicompost,” or worm compost that consists of fecal matter from worms. “It dissolves really fast and it’s basically the same as fertilizer since it has amazing nutrients in it,” Medlin says. She recommends spooning some of it directly on top of the soil to add organic material for growth benefits and to keep the soil from compacting. “It’ll help more than fertilizing would because you’re continually improving the soil versus just mixing it, for a short-term benefit. It’s only slightly more time consuming than adding fertilizer to your watering can, but your plants will love it.”
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