Houseplant Care: Light, Water, and Soil
HOUSEPLANT CARE: LIGHT, WATER, AND SOIL
Here at FGG, the question we hear most often from customers is “How often do I water my houseplant?” It sounds like a simple question, but the answer is actually pretty complicated. Frequency of watering should be based on a combination of factors: primarily light, water, and soil type. So if you want to know how much water your new plant needs, first you’ve got to get to know the plant and its environment.
LIGHT
Understanding the lighting in your space is essential when choosing or placing a houseplant. Each plant will have its own needs, and even the toughest plant, if placed in the wrong lighting, may fail to thrive. It’s also important to understand that there really aren’t any plants that like lower light. When we talk about “low light plants,” we mean plants that will tolerate these conditions better than others; all indirect light plants would prefer bright indirect light, if possible, but some plants do okay when light is quite low. Also the light we are talking about here is sunlight, not interior artificial light; though if your room is very dark, broad spectrum bulbs can help “low light plants” get a little boost. Here are some things to consider when choosing a houseplant or setting it up in your space.
What is the intensity of the light, and what’s my plant’s light preference?
Direct sun:
Beams of light hitting the plant near a window with the most intense light. If you’re in a direct sun spot, you can feel the warmth of the sun on your skin.
Plants for direct sun: Adenium, Alluaudia, Anigozanthos (kangaroo paw), Ananas (pineapple), Beaucarnea recurvata (ponytail palm), Cactus, Caryota mitis (fishtail palm), Clusia, Cordyline, Croton, cycads, Dypsis lutescens (areca palm), Dracaena marginata, Dracaena arborea, Epiphyllum, Euphorbia ammak, Euphorbia ingens, Euphorbia trigona, Euphorbia tirucalli (pencil cactus, sticks on fire), Ficus Alii, Ficus decora, Ficus ‘Amstel King’, Ficus ‘Audrey’, Ficus tineke, Ficus triangularis, Gardenia, Hibiscus, Hyophorbe lagenicaulis, Musa (bananna), Pachypodium (Madagascar palm), Pleomele, Plumeria, Ravanea rivularis (magesty palm), Sansevieria (cylindrical types), Schefflera arboricola, Schefflera amate, Strelitzia nicolai (giant bird of paradise), succulents (most), Tillandsia (silver varietes), Veitchia, Wodyetia bifurcata, Yucca
Partial direct light:
Partial direct light is divided into two categories—”direct diffuse” and “limited direct”—both of comparable intensity. If your spot fits either of the two descriptions below, then it can be considered “partial direct light.”
Direct diffuse: Beams of light are hitting the plant, but the plant is deeper (six feet or more) into a room. The deeper the plant is into the room, the less intense the direct light will be.
Limited direct: The plant is in direct sun (close to a window), but only for an hour or two during the day.
Plants for partial direct light: Adenium, bromeliads, cactus, Cordyline, Croton, cycads, Dracaena marginata, Dracaena arborea, Euphorbia ammak, Euphorbia ingens, Euphorbia trigona, Euphorbia tirucalli (pencil cactus, sticks on fire), Ficus decora, Ficus ‘Audrey’, orchids (most), Pachypodium (Madagascar palm), Pleomele ‘Song of India’, Schefflera arboricola, Schefflera amate, Strelitzia (giant bird of paradise), succulents (most), Sansevieria, staghorn ferns, Tillandsia (silver and green varieties)
Bright indirect light:
This is just beyond the direct beam of light (or through cracked blinds or a sheer curtain filtering direct sun). Bright indirect areas are characterized by a place you can sit and read a novel comfortably without artificial light.
Plants for bright indirect light: Most plants! Alocacia (elephant ears), Anthurium, Aspidistra (cast iron plant), Calathea (prayer plant), Chamaedorea (bamboo palms), Dracaena (wide and narrow leaved varieties), Ficus, Howea forsteriana (kentia palm), Maranta, Philodendron, Pothos, Rhapis, Strelitzia (giant bird of paradise), Schefflera amate, Schefflera arboricola, Sansevieria (flat and cylindrical types), orchids (most), Tillandsia (green varieties.)
Moderate indirect light:
Beyond the bright indirect light. In these areas you wouldn’t turn on a light walking through the room, but if you were hanging out there you would probably have the lights on, even during the day.
Plants for moderate indirect light:
Alocacia (elephant ears), Anthurium, Aspidistra (cast iron plant), Calathea (prayer plant), Dracaena (wide leafed varieties), ferns (most), Howea forsteriana (kentia palm), Maranta, Rhapis, Selaginella; Spathiphyllum (peace lily), Sansevieria (flat types)
Low light:
Dim spots, usually the backs of rooms or hallways where you would always turn lights on, even if just walking in to grab something.
Plants that will tolerate low light: Many ferns; Spathiphyllum (Peace Lily); Anthurium; Zamioculcas zamiifolia (ZZ plant); some Dracaena, such as Dracaena compacta and Dracaena elegans; Kentia palm; Rhapis palm; Aspidistra (Cast Iron Plant); Sansevieria (flat types).
Figuring out your lighting: What factors affect the lighting of a room?
Direction:
North-facing rooms will have the lowest light, often with no direct light. Generally the light will be bright to moderate indirect right up in the windows, but quickly drop to low light deeper into the room.
East-facing rooms will have the second lowest light. This is because morning sun is considerably less intense than afternoon sun. They will often have direct sun in the window and then bright indirect a little deeper in the room, and then drop quickly to moderate indirect and low light.
South / west-facing rooms will have the strongest light. These are generally characterized by very strong direct sun within the first six feet of the window, transitioning to diffuse direct sun deeper into the room, and then moderate indirect and sometimes (but not always) low light at the back of the room.
Obstructions:
Exterior obstructions such as buildings or trees generally reduce the light of a room. A top floor, south-facing room might have blasting direct sun, while the garden apartment of the same building might have only moderate indirect light right in the window. Other times an obstruction can actually increase the light in a room, such as a north-facing room looking at a white wall, which will reflect southern light into the room.
Are there blinds or curtains? If so, try to keep them consistently set the same; plants love consistency! This is a way for you to control the light and thus also have some effect on which plants will work in your space.
How big are your windows? The bigger the window, the more light you’ll have to work with.
Seasonal changes:
Light durations fluctuate seasonally quite a bit. You’ll have less light during the winter and more during the summer. Generally plants have seasonal watering adjustments based on this cycle, with some (including euphorbias, pachypodiums, and adeniums) needing a pronounced dry and wet season. (See more about watering below!)
Here’s a fun tip! Plants that may thrive in hot direct sun haven’t necessarily been grown in that kind of light, so they may burn if placed into exceptionally hot direct light right away. Starting these plants in direct exposure in winter can be a great way to help them acclimate over the spring so they’ll thrive once summer arrives.
The angle of the sun drops as summer moves into fall and winter. This decreases the intensity of winter light and sometimes creates seasonal obstructions. You might find you have more light in winter than in summer, for example if your window is under a deciduous tree that loses leaves in winter, allowing more sunlight through the branches.
Duration of time:
Always consider how long the light is coming into the room, as this will directly affect how much light your plant is able to take in. If the sun only passes through a room for a short period during the day, your plants may not be getting as much light as you think.
WATERING
After lighting, watering is the most important factor when taking care of houseplants. Remember that watering is directly connected to the light conditions; in other words, the same plant might need more or less water, depending on the intensity and duration of the light it’s getting.
The mechanics of watering
Almost all houseplants want to be completely saturated at the time of watering and not left standing in water afterward. The most common error when watering houseplants is not fully saturating the soil. Even plants that like to go totally dry between waterings need to be fully saturated when watering time comes around.
Here are a few methods of watering you can try:
Top watering with a saucer:
Place the plant in a saucer.
Make sure the edge of the soil hasn’t separated from the pot, as this will allow water to run down the side without penetrating the soil.
If the soil has in fact separated from the pot, pack some soil into this crack.
Slowly pour water over the entire soil surface.
When you see water coming out the bottom, stop watering.
Give the plant some time (usually hours) to see if it soaks up the extra water in the saucer. If it does, add more until there is standing water in the saucer.
If the plant hasn’t used the extra water in 24 hours, remove the water using a turkey baster, or you can put a rag into the water, let it soak up the extra, and then wring it out.
Bottom watering with a saucer:
Essentially you’ll skip the first part of top watering; instead of pouring water over the soil surface, just place water in the saucer and allow the plant to soak it up. Repeat this process over and over until you reach saturation (when the plant no longer soaks up the water you add to the saucer).
Watering in a sink/tub/deck etc:
To achieve saturation without a saucer, slowly run water over the entire soil surface and continue to do so well after the water comes out of the bottom.
This method doesn’t work well with hydrophobic (completely bone-dry) soil.
How frequently do houseplants need water?
The most important thing to understand about watering houseplants is that it is not based on a time period, such as once a week, but instead based on the moisture remaining in the soil. And remember that the moisture remaining in the soil will change depending on many factors. Plants in brighter light, near a heater or a fan, or in a warm room will tend to be thirstier. Those in lower light with little air movement will drink more slowly. If your home is in the fog belt, humidity and reduced sunshine will make your plants less thirsty; inland areas with hotter temperatures and low humidity will make them thirstier, especially when subject to air conditioning and heating systems. A drafty old Victorian will have a much different climate than a new, well-insulated modern building. A large plant in a small pot will be thirstier than a small plant in a large pot. Thus, as plants grow, they can become thirstier, and a plant shifted into a larger grow pot may require less frequent waterings.
Some plants need to go totally dry between waterings, while others prefer to stay evenly moist, or somewhere in between. When you first bring your plant home, get familiar with it by poking around the soil every two or three days to find out how moist it is, keeping the plant’s preference in mind. The easiest way to monitor the moisture of the soil is to take a look at it. Does it look soggy-wet, damp, or dry? Then go ahead and get your fingers in there and see how damp it feels, being sure to dig down a couple inches into the pot. (The “tips and tricks” section below has some more tips for gauging the moisture of the soil.)
What is my plant’s moisture preference? Read through the categories below and find out about the plant you’re bringing home.
Plants that should be watered when the soil is completely dry:
These plants want to go dry from the top of the pot to the bottom. Remember the top may feel dry, while residual water remains deeper in the pot. (Read on below (link) for some tips to determine how much water remains in the pot.) These plants also don’t want to go dry, then bone dry, and then sit around for another month or so; once they are totally dried out, they want water! These will want water around every two to five weeks.
Sansevieria (snake plant), cactus, Agave, Euphorbia ammak, Euphorbia ingens, Euphorbia trigona, Euphorbia tirucalli (pencil cactus, ‘Sticks on Fire’), most succulents, Adenium (winter), Aspidistra, Pachypodium (winter).
Plants that should be watered when the soil is mostly dry:
These plants want the top two thirds of the pot to dry out, while always having some moisture left deep in the pot. Generally they’ll want water every one to three weeks.
Dracaena fragrans, Dracaena massangeana, Dracaena marginata, Yucca elephantipes, bromeliads (should always be watered from above filling the ‘cups’), hoyas, peperomias, aeschynanthus, some succulents, Adenium (summer), Pachypodium (summer), most orchids, staghorn ferns.
ZZ plant should dry out between waterings.
Plants that should be watered when the soil surface is dry:
Water these plants when the top layer of soil is dry, but you can still feel moisture just below the surface. These are the plants that often fall into the once-a-week watering cycle. Remember that the ‘surface’ will go deeper on larger pots, so that a 14 inch diameter pot will need to dry out a couple inches deep, while a 4” pot will only need to dry in the top ½ inch or so.
Most plants! Ficus, Philodendron, Pothos, Kentia palm, Rhapis palm, Chamaedorea (bamboo palm), cycads, Schefflera, Strelitzia (Giant Bird of Paradise), crotons, Cordyline.
Plants that should be watered when the soil surface is damp:
These plants like to stay evenly moist. When you touch the surface and it’s no longer soggy, but feels like a well-wrung sponge, it’s time to water. Often these plants can be left in a little standing water to extend the watering period. These could be watered several times a week, or less if they are left standing in some water.
Fishtail palm (Caryota mitis), Selaginella (only water the soil, not the plant), most ferns, Maranta, Calathea (Prayer Plant), Spathiphyllum (Peace Lily), Anthurium, Alocasia (Elephant Ears), Dracaena sanderiana (Lucky Bamboo).
Maranta plants like to stay evenly moist.
Watering tips and tricks:
While it’s not necessary to know the exact amount to water each time, for those who just love precision, here are some steps you can take to find the volume for each watering!
Start with a total measured volume of water, say 5 cups.
Water as directed above and allow the plant to reach saturation. Note how much water was unused, say 1 cup.
Pour out and measure the water left in the saucer, say ½ cup.
Subtract the unused and leftover water from the total volume. In this case: 5 - 1 - 0.5 = 3.5. So it takes 3.5 cups to saturate your soil when the plant is ready for water.
If there’s still water in the saucer after 24 hours, apply less volume during future waterings.
Succulents grown in non-draining containers require very careful watering in small quantities. Many of our pre-planted succulent compositions fall into this group. Check out our tutorial on how to water succulents in containers with no drainage here.
With smaller planters, try lifting up the pot/plant to get some insight about when you should water. As the pot dries out, it will become noticeably lighter.
For plants that like to totally dry out, poke a wooden chopstick into the soil. If it comes out with soil on it, the planter isn’t ready for water yet.
Sometimes, for plants that like to go totally dry, the soil might become hydrophobic and won’t easily absorb water. (Imagine a totally dry sponge and how water just runs off its surface when you first try to wet it.) In this case put the plant in a deep saucer and allow it to soak up water over time until fully saturated.
Once a year, you should pull out your plant to make sure its roots haven't filled the drainage holes. Once they do, the soil will become waterlogged, hurting the plant.
Check in with your plant when you turn the heat on in the fall, and back off again in the spring, as these are the times the watering will shift, sometimes dramatically.
Humidity is a serious consideration with how often to water. Remember this in kitchens and bathrooms, where there can be a great deal of moisture in the air.
Plants that want to totally dry out between waterings will often show shriveling when they want water. You can also lightly squeeze them. You’ll feel that they are a little squishy when they dry out, and after you water, they will plump back up and be hard again.
Water is made easier by using the cachepot system, allowing you to have cleaner lines and a deeper saucer to catch water without overflowing.
Troubleshooting:
Wilting plants or plants that look dull are often under-watered, but this can be a symptom of over-watering, too. Make sure you feel the moisture of the soil; if the soil is soggy-wet, there’s a chance that the roots have rotted, and thus the leaves aren’t getting any water, simulating the look of an under-watered plant.
Many leaves uncurl as they grow, but if you find a mature leaf that’s curling up, it’s likely a symptom of under-watering.
Yellowing leaves or brown spotting can be a sign of nutrient deficiencies, but is usually a sign of over-watering.
Brown crispy tips / edges is usually a sign of underwatering.
For succulent plants, shriveling (or a loss of plumpness when squeezed) is a sign that the plant is under-watered.
Inspect your plant’s roots. If they are soggy, slimy, and brown, the plant is seriously over-watered.
For small-to-medium-sized well-rooted plants, you can actually lift them out of the pot without the soil falling off, and inspect the moisture in the soil.
SOIL DRAINAGE
After light and water, soil will be the next consideration. In some ways, this is more complex than lighting or water, as soil can contain dozens of different ingredients, so here we’ll consider only the basic principle of drainage. Drainage is how quickly water can move through the soil, and also how long water will be retained in the soil. A soil with more drainage will retain water for a shorter period of time. When purchasing soil, know that cactus mix has more drainage than potting soil.
How do you understand your soil drainage?
By material:
Pumice: Small white rocks, excellent drainage.
Lava: Small black or red rocks, excellent drainage.
Sand: Coarse sand, decent drainage. The larger the sand, the better the drainage.
Perlite: Very light, white, foam-like rock. Excellent drainage, but often floats to the surface after subsequent waterings, in effect decreasing the drainage in the soil.
Wood Chips: Good for drainage when fresh, but drainage lessens as the chips decompose. The larger the chips, the better the drainage.
Peat / Coir: Looks like dark brown sawdust, poor drainage.
By visual inspection:
The drainage component of a mix will usually be visible when inspecting the soil.
By touch:
Massage or pinch the soil; if it feels coarse, it has good drainage. If it feels soft and powdery when dry, or spongy when wet, the drainage is poor.
What is my plant’s drainage preference?
Good drainage (cactus mix with around 50%-60% drainage by volume):
Sansevieria (Snake Plant); cactus; Agave; Euphorbia ammak, Euphorbia ingens, Euphorbia trigona, Euphorbia tirucalli (pencil cactus, ‘Sticks on Fire); most succulents; Adenium; Dracaena; Hoya; Adenium; palms (including Kentia, Rhapis, Caryota); cycads; Pachypodium; Cordyline; Anthurium; orchids (usually planted in orchid bark); staghorn ferns (can also be mounted with moss/bark).
Average drainage (potting soil with around 20%-30% drainage by volume):
Most plants! Ficus; Philodendron; Pothos; Kentia; Rhapis; Selaginella; ferns; Maranta; Calathea (Prayer Plant); Spathiphyllum (Peace Lily); Alocasia (Elephant Ears); peperomias; Schefflera; Strelitzia (Giant Bird of Paradise); Croton.
Drainage tips and tricks:
Very important! Houseplant growers often grow plants in soil with little to no drainage. Since the plants are in very hot/bright greenhouses, the plants thrive, and this allows the growers to water much less frequently. If you find your plant was grown with little to no drainage, be sure to re-pot it immediately, as it will require adequate drainage for its forever home.
Almost all plants need a hole in the pot, so make sure you’ve got one unless you know your plant is the exception to this rule.
Put a screen over the hole in the pot to keep the soil from falling out.
If it seems like the soil just won’t dry out, you may have too little drainage or the roots may have plugged your pot’s hole.
As you can see, the answer to the question “How often should I water my houseplant?” involves many factors, including most importantly the gradients of lighting, water, and soil drainage. Once you get to know your plant’s preferences in these three areas, take note of them when watering over the course of several weeks. Eventually you’ll find that a watering cycle emerges, such as once every 10 days. Then you’ll have your answer, and you’ll have a happy plant, too!
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