These houseplant ‘hacks’ could do more harm than good

Here, horticulturists — i.e. genuine houseplant experts — share a few “hacks” that could wind up doing more harm than good.

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Soaking banana peels in water

YouTube videos of people soaking banana peels in water, then giving the liquid to their houseplants have racked up millions of views. They claim the water absorbs nutrients from the peels that will help the plants thrive. But horticulturists say there’s no real evidence to support this.

“Watering with banana water isn’t bad for your plants,” says Rich Christakes, a horticulturist and founder of Ship My Plants, but “it likely isn’t doing much at all.” And if you assume that it’s an acceptable replacement for conventional fertilizer, you could actually end up depriving your plants of nutrients, “neglecting and harming [them] in the long run,” he says.

While it’s true that bananas are rich in calcium, potassium, magnesium and phosphorus, plants can’t access those things unless they’re fully broken down. So, if you still want to use your peels to help your houseplants, Christakes suggests composting them first, then adding the finished organic matter to the soil.

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Adding coffee grounds, eggshells and produce scraps to soil

Hundreds of TikTok and YouTube videos tout the benefits of enriching houseplant soil with all manner of kitchen scraps, including leftover coffee grounds, eggshells and the remnants of fruits and veggies. But none of these are reliably helpful, and in fact, they could cause problems.

The amount of nutrients in coffee grounds varies by brand and type of coffee, explains Julie Weisenhorn, an associate extension professor within the University of Minnesota’s horticultural science department. So there’s no guarantee they’ll do anything to boost the health of your plants, though you could put them to use by adding them to your compost bin. “If you’re concerned about nutrients, it’s better to use a fertilizer that’s labeled for your plants,” she says.

Another hack floating around social media claims that ground-up eggshells add calcium to houseplant soil. But simply tossing them into a planter skips some key steps, says Terasa Lott, state coordinator for the South Carolina master gardener program. “Eggshells do have calcium, but it needs to be broken down so that it’s available to plants,” she says. Once again, composting them and using the finished product to amend soil is the correct approach.

The same goes for burying produce scraps directly into your pots. This so-called hack can actually hurt, attracting harmful pests and creating a smelly mess. Plus, houseplants don’t have a lot of soil space: “If you start adding things into the soil, you could create a more detrimental growing environment,” Weisenhorn says.

Using mayonnaise for shiny leaves

According to another myth on TikTok, you can rub foliage with mayonnaise to make it shinier. In reality, this can seriously damage houseplants by clogging the stomata in their leaf tissue.

“Stomata are little openings that release air vapor when the plants become too turgid,” Weisenhorn says. “It’s a regular process of the plant and physiological function.” Slathering them with mayo, she says, is similar to clogging the pores of your skin with something greasy. And not all houseplants are meant to be high-gloss. “These plants are living organisms and they have a certain look; they don’t all have super shiny leaves,” she says.

Still, regularly cleaning leaves is an important aspect of houseplant care because dust prevents the leaves from absorbing sunlight and hinders photosynthesis. To do so responsibly, Weisenhorn recommends wiping them down with a damp cloth or rag, or gently spraying them with water.

Watering houseplants with ice

Videos promoting watering with ice cubes can also lead to unhappy houseplants. The advice probably stems from the common practice of watering orchids with ice — a convenient method to prevent overwatering them. But it’s a bad idea to deploy the approach with other types of plants, experts say.

Unlike orchids, which are often planted in moss, “most houseplant roots are in soil so they need to be watered thoroughly,” Weisenhorn says. Plus, Christakes says, “Houseplants are tropical plants that never see freezing temperatures in their native habitat.” This means watering them with ice could cause root shock, damaging the root and even killing them, he says.

Lauren David writes about gardening and sustainability.