How to keep your indoor plants alive

Oct. 31, 2019, 7:17 PM UTC

By Brianna Steinhilber

Do you have a graveyard of houseplants you just couldn’t keep alive? I do. There are the dozens of succulents I thought would thrive on my kitchen windowsill, only to wilt, brown and crumple into a heap of dust a few weeks later. Then there are the two beautiful palms that I impulse-bought online from The Home Depot and had delivered right to my doorstep the next afternoon. They stood in all of their beautiful, leafy glory for approximately 2.5 weeks until the leaves turned yellow, drooped, and dropped off one by one.

But it turns out I'm not cursed with a black thumb. I was simply making some very common, rookie mistakes when it comes to plant care.

“There’s no such thing as green thumb or a black thumb, it's more about how much you pay attention to your plant,” says Christopher Satch, plant scientist, instructor at the New York Botanical Garden and board member of the Manhattan Orchid Society. Satch says we all have the ability to grow healthy indoor plants, it’s just about understanding the basics of plant care and listening to your plants when they tell you (er, show you) what they need.

Where and how to buy indoor plants

The first step is selecting which plant to bring home. You may have plans to make a pit-stop at a big box store like I did, but Satch says that, for beginners, this isn’t the best place to make your purchase.

“Go to a reputable garden center or nursery, ideally family owned because they’ve been doing this for years and years,” says Satch. “That doesn’t mean that Home Depot and Lowe's don’t have their place. Plants [from big box stores] are more for people who already know what they’re doing, they’re not really for beginners. It’s a giant warehouse; the onus is on you to figure out: Is this plant doing well? How do I plant that? Where does this go in my home? There’s no real education behind it. If you’re a beginner, go to a local plant shop, or nursery or farm to get your plants.”

And while shopping online isn’t off the table, be careful where you place your order. Satch says to be careful of unscrupulous sellers. “If you do go online make sure it’s a nursery or plant store, and buy from someone well established that follows regulations with shipping, etc.”

Know your space and the time you’re willing to put in

“Make sure the plant that you’re buying is the kind that can live in your space. I’m guilty of this too, where I fall in love with a plant and take it home and then realize I don’t have the conditions the plant wants. And it’s a very sad journey downhill. Always make sure that you know your conditions at home,” he says. Things like access to light (the most important factor according to Satch), temperature and humidity are things to take into consideration.

The next thing you should ask yourself is, how much attention are you willing to give to your plant? "If you’re someone who is really busy, then you might need something that doesn’t want your attention as much, like a ZZ plant or a succulent or cactus,” says Satch. If you’re a person who wants to touch and work with your plants every day, he recommends plants like orchids and ferns.

How to choose a healthy plant

So you know what type of plant will work in your space, how do you select the right one to bring home?

“People will see a plant they like, take it home and ask, ‘why is this plant dying?’ The best way to have success with plants is to start off with a good, healthy, vibrant plant,” says Satch. “It takes a little bit of an eye that you develop over time, and a little research on the plant you’re about to buy.” But focus in on two things: Assessing any damage and looking for new growth.

“When you’re buying a plant, you want to understand the difference between mechanical damage, like humidity or a leaf that was bent and ripped, and fungus that can spread. The way you can tell the difference between whether it is a fungus or humidity damage is a fungus is usually asymmetrical and will attack one part of the leaf unevenly, whereas humidity damage will attack the leaf evenly all the way around,” says Satch. “In a plant that grows fast like a begonia, you’re better off removing the damaged leaves in store. It’ll have new leaves in 3-4 weeks. I do it at the garden center table, so that way you don’t have to bring the disease into your home.” Then, look for new growth, healthy leaves and new buds or stems are a good sign that the plant is healthy and will continue to grow when you bring it home.

Before you leave the store, stock up on supplies

Fertilizer is a must. “When your plant is in nature the universe is, in theory, infinite. If the plant runs out of nutrients where it is, it just grows its roots a little wider and finds new nutrients," Satch explains. "When it’s in a pot, you are the master of its universe. Fertilizer is a nutrient punch. Over time, the plant will exhaust the nutrients and you can re-pot it or fertilize it, or both. It basically just replenishes the nutrients that the plant uses up.”

Any brand will do, just be sure it has a ratio on the front label — called an NPK number. “The three numbers stand for nitrogen, phosphorous and potassium. Just follow the instructions on whatever you buy and you can’t go wrong.”

Other than fertilizer, be sure to pick up a pot with drainage holes. “If you use pots without drainage holes it gets much more complicated and you have to be much more careful with your watering,” says Satch. You will also need a saucer to catch water runoff.

What to do when you bring a new plant home

You’ve got your beautiful new plant, fertilizer and a ceramic pot (with drainage holes!) in tow, so it’s ready to be set on the windowsill and displayed, right? Not so fast. There are a few steps you must take to ensure that your plant thrives in your environment — and that you aren’t tossing yet another pot of dry soil and brown leaves into the trash in a few weeks.

First, always re-pot your plant. “Go about an inch or two larger than the plastic pot that they’re in,” says Satch. “A 6-inch plant should go in a 7- or 8-inch pot so it has room to grow, because the goal is always to have your plants grow.
Spray it with insecticide. “You want to spray it down with some kind of insecticide or pesticide,” says Satch. “You can use different things; I use horticulture oil, which is a petroleum distillate. You mix it with water and spray the plant top and bottom and all in between the leaves. You want to make sure any insect, whether it’s a mite or a mealy bug, is killed before you integrate it with your other plants so you don’t have an infestation on your hands.”
Quarantine your plant. “When you bring it home, set it in a quarantine area for a couple of days before you mix it with your other plants," says Satch. "Don't worry if it's not by a window, they can take that kind of light condition, only for a couple of days before they start dropping leaves."

Caring for your indoor plants

Now your plant is ready to thrive! Here are the basics to keep your indoor plant healthy (and alive).

Light

“The fail-safe is, if you don’t know where to put a plant, put it in the window,” says Satch, who says that there is no such thing as a ‘low light’ plant. “Light is food for plants. Plants literally eat the sunlight. So for them to do well they need as much sunlight as possible. If you [give them] low light, it’s like putting your plant on a diet,” he says.

You should also consider where your plant species originates from. “Different plants come from different parts of the world and have different light requirements. Some plants like succulents, cacti or begonias, they’re from lighter areas in their natural environment and they need quite a bit of direct sun indoors. So you want to place them in the sunniest window that you have. Then there are plants that are from more shaded regions, like a Birds Nest fern or a Boston fern.”

And while it may seem like a no-brainer, the bigger the plant gets the more light it wants, says Satch. So while a plant may start on an end table getting some indirect sunlight, it may require a move towards the window as it grows. “I’ve seen a lot of set ups where people will put a plant in the middle of the room and in the middle of a room is not where a plant wants to be. All plants do very well in windows,” he stresses.

Water

When it comes to watering, Satch has heard it all: “I’ve heard so many things: some people spritz their succulents, don’t do that. Some people use cubes on their plants, definitely don’t do that.”

If you listen to no other advice, follow this main rule of thumb: water when the soil is dry. Follow these other tips to ensure you’re not over or under-watering your plant:

Don’t count days. “I tell everyone, don’t count days [between watering]. Feel your soil or whatever it’s planted in every couple of days. If the soil is dry, then you can water it. Some plants depending on the season may be watered every couple of days, to every week, to even every 2 weeks. But I wouldn’t go more than 2 weeks without watering a plant because then it starts getting too dry.”
The soil will tell you when to water. “Feel the soil an inch or two deep. The soil will tell you [what the plant needs]: if it’s moist and smells, it’s too wet and you’ve started to rot your plant; if it’s bone dry and dusty, you should give your plant water. It’s better to err on the side of dry then wet.”
There's a proper way to water a plant. First, always use warm water. “Most houseplants don’t come from cold areas and warm water absorbs faster into the soil, so it’s more efficient,” says Satch. Be careful to aim your watering stream towards the base of the plant. “You don’t want to throw water all over the plant because you run the risk of an infection or fungus taking hold in one of the leaves,” says Satch. “Water a little bit at first, wait for water to sink in, then water a little bit more, let that soak in, then add a bit more. Keep doing this until you see water build up in your saucer,” he adds. “You don’t want to dump water in too fast. What happens is when the soil is too dry, it actually becomes water repellent, and the water will just rush down the sides of the pot into the bottom, [going] around the roots.”
Take a cue from nature and mimic a rainstorm. “You don’t want to be too conservative with the water because think about it: What [happens] in nature? When it rains, it pours. It gets very wet, and it sits in the wetness for like a day, and then the sun comes out and dries everything up. That’s exactly what you want to recreate for your houseplant," says Satch. "When you water, every single time, make sure your soil is saturated. Let it sit in the excess water in the tray for about a day, if after a day it hasn’t absorbed what’s in the tray, dump what’s left.”
To spritz or not to spritz? People love to spritz their plants, but not all plants need, or even like, being spritzed daily. Do not spritz aeroids like pothos, monsteras, or peace lilies — anything with a waxy leafy look, says Satch. “With plants like this, there’s no water going through those waxy leaves, you’re actually doing them a disservice by spritzing them because you’re making it easier for fungi to penetrate that waxy layer and attack the leaves.” But there are a few plants that do want to be watered all over, like air plants, orchids and ferns — these are plants you want to spritz.
How to water a succulent. Succulents pose a particular issue for many people, since we assume them to be such low-maintenance plants. Yet, we’ve all had that desk succulent go from cheery to sad seemingly overnight. “For succulents, you have to think about their natural environment. Feel the soil and make sure it's bone dry when you water it, and when you do water it, you want to saturate it. Maybe every two weeks," says Satch. “If it’s in a bright sunny window, that sun will dry it out real fast. Especially the smaller ones, they dry out super-fast. So you can water it as soon as it hits dry.” He also says to be aware of seasonal changes — while a succulent may need to be watered every few days in hotter, sunnier months, they may be able to go a week or two between waterings during the colder, winter months.

Signs of trouble

“In order to figure out what’s going on with a plant you have to diagnose it holistically. What’s happening? Are the leaves dropping, are they turning yellow? How does the soil feel?” says Satch. Here are some warning signs to be on the lookout for:

Roots are rotting. "If the soil is soft and mushy and the roots at the base are climbing out of the pot, you are overwatering," he says.
Edges turning black. “A lot of people will think this is low humidity. Not always. Sometimes it’s a fungus that’s eating away at the leaves,” says Satch.
Yellow leaves. “It could be anything. Yellow leaves is just warning sign. It could be too hot, it could be too cold, it could be too wet, it could be too dry, which is why you always look for secondary symptoms," he says. "One yellow leaf is not necessarily a cry for help. If the rest of the plant looks perfectly green, sometimes it’s just an old leaf or sheath that’s dying off and that’s perfectly natural and normal.”
Wrinkled or drooping leaves: You're under-watering and your plant is thirsty.
Lower leaves are school-bus yellow: This is a sign of over-watering.
Leaves dropping off: "Leaves dropping can be for many reasons, but indoors, the most common is not enough light," says Satch. "Plants do not see light like we do, and light is their food. No food, no leaves. The cure is to put into (not next to) a bright window."
Gnats: If you see gnats, you’re watering too much and you’re not letting it dry out completely between waterings.

Plant care cheat sheet

Assess for damage before you bring your plant home.
Use insecticide and quarantine.
Change the pot and add fertilizer.
Remember: “Low-light” plants don’t exist — all plants need some direct sunlight.
Take a cue from nature: Only water when soil is bone dry and then saturate it.

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