Very important! Plants capture energy from sunlight through photosynthesis. During this process, certain wavelengths of light are captured by the plant’s chlorophyll pigments, while other wavelengths of light are captured by the plant’s phytochrome pigments.
These wavelengths are used to assist the process of photosynthesis, and drive other important biological functions of your plant.
Different plants have different light-level needs, based on the way that they have evolved.
For example, forest-dwelling ferns have evolved to need less light than desert-dwelling succulents. Knowing what type of environment a plant is native to will help you determine what kind of light it will be happiest in. To determine what kind of light your apartment or office has, start by figuring out what direction your windows face. Remember, the sun rises in the east, swings to the south, and sets in the west.
South windows - brightest, most intense, direct light East/West windows - bright to medium, but not as intense, indirect light North windows - medium to low, indirect light
Once you’ve figured out what direction your windows face - see what is outside your window! If your window faces south, but there’s a shady tree or large building in the way, the amount of light could be greatly reduced and more similar to that of a west-facing window. The same is true if you have thick curtains in front of your windows that you rarely open. (Open them up and let the light shine in! Or replace them with a sheer fabric. Your plant will thank you.) Here’s a quick way to determine what kind of light you have - ‘the hand test’. At mid-day, spread your hand out about a foot above where you plant to put your plant. Now look at your hand’s shadow - if you see a:
Well-defined shadow - bright light Fuzzy shadow but still recognizable as a hand - medium light Only faintly discernible shadow or no shadow - low light
Remember that the duration of light is important, too. If your south-facing window only receives one hour of direct sunlight a day, then it would be considered more of a east/west-facing, medium light window. Ideally, most bright light plants like succulents and cacti need 6+ hours of direct sunlight, or a full day of bright, indirect light. Most medium light plants like an hour or two of direct sunlight, and bright, indirect light for the rest of the day. And most low light plants like a full day of lower, indirect light, and to be a little further away from the window.
There’s an old adage among horticulturists - “The darkest shade outside is the same as the brightest light inside.” This is true even if your window receives bright, direct sun. Why? Because outside, light comes from all directions! Inside, it only comes from one direction - your window. As the seasons change, so will the quality and directionality of your light. Keep an eye on where the sun is at different times of the day. If, in summer, the sun swings high over a building to shine directly in your window, it may not shine in your window when it swings low in the winter.
Plan your plant placement appropriately and change seasonally, if necessary. Supplemental lighting can be used in cases where either existing light is not enough to keep your plant healthy and happy. The best supplemental lights will come from the red and blue LED light bulbs that were designed with the specific wavelengths that plants need. You can also get away with a CFL bulb in the “warm” region ( less than 2700) in the Kelvin spectrum (Kelvin doesn’t mean anything with regards to light for plants).
Remember, plants don’t see light the way that we see light!
What we may see as a brightly lit room (by lamps, not sunlight) may be completely dark to the plant. White light is made up of the three primary colors of light - red, green, and blue. Most white indoor lights for humans are rich in light in the green spectrum, with only a little red and a little blue. But plants are green because they reflect green light away from themselves, and absorb blue and red light. Because of this, if you decide to use a supplemental light, you’ll need a specialized plant light bulb (with red and/or blue wavelengths) for your green friend.
All plants drink with their roots! Only certain epiphytes (like air plants) and nonvascular plants (like moss) are exceptions to this rule.
Different plants that evolved in different environments will need different amounts of water - just like different plants that evolved in different environments will need different amounts of light.
Desert-natives like cacti and succulents prefer it dry, and will benefit from much less water than humidity-loving ferns, who need a good shower or two a week. Knowing your plant’s native habitat will be key in helping water appropriately, as will plant size. It’s important to be flexible in your plant care habits!
One of the biggest mistakes is sticking to an exact watering schedule - i.e. watering on exactly the same day every week. For the majority of plants, only water when the soil is dry, and not just dry on the surface, but dry 2 inches down into the soil. That means feeling your soil, and becoming more familiar with soil moisture levels. You’ll also notice that smaller pots, with less soil, will dry out faster than larger pots. So if you have two of the same plants, but in two different sizes, one might need water more often than the other.
Although most common houseplants prefer frequent waterings, there will be special exceptions for certain plants such as cacti, succulents, and euphorbs. When watering these plants, think about recreating the desert’s weather. The desert is super dry for the majority of the year - with only a few rare periods of rainfall. When you water your cacti, succulents, and euphorbs - feel free to give them a soak, but make sure they dry out completely the same day, like they would in the desert. Then wait a considerable amount of time before watering again.
During the summer, when the sun is at its strongest, smaller fleshy succulents might need to be watered more regularly, about once every two weeks or so - in comparison to once every month.
Other plants, such as ferns and some tropical plants, will need to be watered about once a week and be given higher humidity to stay happy and healthy. Some ferns actually demand that their soil be kept perpetually moist (but not to be confused with soaking wet). Air plants love humidity too, and, along with ferns, are perfect picks for a bathroom with a window.
It’s important to note that most of your plants will prefer warm or tepid water over cold water, and you’ll notice that warm water absorbs into the soil better as well. Don’t splash water onto your plant’s leaves (unless it’s an orchid, air plant, or a fern, that will appreciate the added humidity). You’ll notice that most tropical plants have waxy leaves. This is because the rain in the rainforest is just too much, and the leaves risk fungal infection if water sits on them too long. Their waxy leaves help water slide off quickly.
As far as the amount of water to give your plant? If you’re unsure - a general rule of thumb is to give about ¼ the volume of the pot as water, or to soak the soil.
Your home is a unique environment! It is important to be familiar with your home’s microclimate and flux. Being in-tune with this will help you better adjust your environment for your plant - or, better yet, pick a plant perfectly suited for your environment.
Soil is a major source of vitamins for your plant, and the place for your plant to make beneficial associations with soil microbes. Many plants actually benefit from forming root associations with these microbes and fungi. To keep the population of soil microbes fresh, it’s important to change the soil (i.e. repot your plant) once every 12 to 16 months.
Humidity is important for some common houseplants, like ferns and air plants, but is also beneficial for the health of other tropical plants. Although many tropical plants can withstand some dryness, they’d prefer not being subject to dry air. Dry air is especially a problem in the wintertime, when forced-air vents, as well as outdoor conditions, vastly decrease air humidity levels. It’s best for your health and your plants health to invest in a big humidifier to raise the humidity. You can thank us later.
Never put your plants near a radiator or an A/C unit! You’ll cook - or chill - them to death. If the only window you have is by a radiator, consider hanging planter options, or a radiator cover on which you can place a raised shelf. Three feet above the radiator or more is usually safe.
Beware of balconies! Plants like to be where you like to be. If it’s too hot and windy on the balcony for you for spend a full day, then it’s too hot and windy for your plant! More often than not, plants placed on a fire escape, balcony, or rooftop that’s surrounded by bricks and concrete will cook to death in the intense summer heat. All that concrete and baked earth amplifies the heat. Keep in mind that you can usually cook an egg on the sidewalk in the middle of July. Ouch!
Recreate a plant’s natural environment to make them thrive!
Remember that your plant is not a piece of furniture. It’s a living, breathing organism that grows and responds to you and the conditions you provide. It’s important to make it happy. And if you can, by meeting its basic requirements, then your plant will make you happy back. Because plants make people happy.
Or, follow these tips:
- Group plants together
- Rest plants on top of a water filled tray lined with rocks or pebbles (but don’t allow them to sit IN the water)
- Temporarily put a plastic bag over the plant (try to keep the plant from touching the bag) until it recovers