Indoor Foliage Plants
General care information for keeping your house plants healthy.
Here’s a segment of gardening where you and your plants are working with a handicap. Most house plants are native to the tropics and sub-tropics, where the climate is warm, bright, humid and mildly breezy year round. That’s drastically different than the dry, limited-light environments in most of our homes and offices. So it’s important to understand right off the bat that your house plants usually aren’t going to get the conditions to which they’re naturally adapted.
That gives you two choices. You can either stick with varieties that adapt best to our not-so-perfect environments or adapt your environment as best as possible to match the plant’s needs.
As with any plant, how well a house plant grows will depend on where you put it. At the top of the list is the amount and type of light your site has to offer.
We base our plant suggestions on four types of light:
1.) Low light: These areas include shadowy corners, north-facing windows, other windows that are shaded by buildings, porches or drapes, and offices with fluorescent lighting within a few feet of the plants. Varieties that tolerate low light include Chinese evergreen, pothos, philodendron, cast iron plant, snake plant, Dracaena marginata, corn plant, peace lily, homalomena, arrowhead vine and the “ZZ” plant.
2.) Moderate or diffused light. These areas include bright windows partly shaded by sheer curtains, windows partly shaded by trees or overhangs, and areas about 4 or 5 feet away from a bright window. Plants that adapt well to that light include calathea, fiddle leaf fig, rubber tree, spider plant, prayer plant, dieffenbachia, creeping fig, fishtail palm, parlor palm, birds nest fern, rabbit’s foot fern and button fern.
3.) Bright indirect light: This is an area within about 3 feet of a bright window but not in the line of direct sun. Plants well suited to this light include English and Swedish ivies, wandering jew, ficus, schefflera, Norfolk Island pine, areca palm, yucca, asparagus fern, Boston fern, African violets and hoya.
4.) Full sun: This is an area that gets at least 4 hours per day of direct sunlight with no shading by trees, overhangs or curtains. Most blooming plants prefer this type of site. Among full-sun lovers are hibiscus, flowering maple, gardenia, lipstick plant, goldfish plant, jade plant, kalanchoe, jasmine, zebra plant, croton and miniature roses.
Other enlightening points
In general, southern exposures have the most intense light. Eastern and western exposures typically have about 60 percent of the intensity as south, and northern exposures are only about 20 percent as intense.
Also remember that light intensity goes down the farther the plant is from the light source. Even the cleanliness of the window can affect light intensity.
You can sometimes compensate for low light intensity by increasing the length of time the plant is exposed to light. If a different window doesn’t achieve that, artificial light can be supplied. So-called “grow lights” best mimic the sun’s natural light, but ordinary cool white fluorescent lights are often enough to give a helpful boost to foliage plants. Just don’t allow more than 16 hours of light a day because plants need some darkness to develop properly. (A few plants, such as poinsettias, kalanchoe and Christmas cactus are “daylight sensitive” and won’t flower until they receive 11 hours or less of light per day.)
Once the plant is sited properly, the most likely thing that can go wrong is over– or under-watering. Incorrect watering is easily the No. 1 killer of house plants.
There’s no one rule on how often to water. That varies depending on factors such as type of potting medium, how dry the air is, time of year and size of the pot. The best way to know when to water is a simple finger test.
Every few days, stick your index finger down 2 inches into the soil (that’s about up to your second knuckle). If it’s damp, wait. If it’s dry, water. In a smaller pot, a 1-inch depth is fine. The reason for this is that most of the plant roots are in the bottom two-thirds of the root ball. If you water every time the surface dries, you’re probably going to overdo it.
When you do water, put enough on so it just begins to run out the bottom. This will let you know you’ve wet the whole root ball, and it’ll help leach out some of the excess salt from your fertilizer. Don’t let the pot sit in the drainage, though. Pour off excess water. If possible, water with unsoftened water.
You could also use a stick or dowel instead of your finger. If you can’t get either down 2 inches into the soil, it’s time to repot. Or else your potting medium is too heavy or compacted. And if you’ve let your plant dry too much to the point where the potting medium has pulled away from the side of the pot, you may need to water and drain several times to rehydrate the medium sufficiently.
One other good practice is to leach salts out of the medium every 4 to 6 months. This is done by running unsoftened water through the pot in an amount that’s equal to at least two to three times the volume of the pot.
Other healthy moves
Most house plants grow best with daytime temperatures between 70 and 80 and night-time temperatures of 55 to 68. Most also like fairly humid conditions, which is best achieved by room or whole-house humidifiers but to some extent by placing pots atop pebble trays filled with water. Another way to raise humidity is by grouping plants closely together.
Most house plants like going out for a “summer vacation” when our weather is warm and humid. Early June is normally a good time to put plants out, and mid-September is when to get them back inside. During both moves, it’s important to gradually increase and decrease light over a 4– to 6-week period. Especially don’t move a plant from the low light inside to full sun outside the next day or you’ll fry it.
Most house plants are sensitive to drafts (especially hot ones), so keep plants away from heating and air-conditioning vents and doors.
Balanced fertilizers (such as ones marked 20-20-20) are fine for most house plants. Bloomers appreciate ones that are a bit higher in phosphorus and potassium (the last two numbers of those formulas). In general, fertilizing every two weeks during the growing season (March to September) is fine, and most plants do not need fertilizer at all over the winter.
Occasionally your plants will need to be repotted. They’ll let you know it’s time by pushing roots out the bottom drainage hole or by growing roots so thickly that you can’t stick your finger into the potting medium. Most plants are best repotted in late winter to early spring.
To repot, gently remove the plant and loosen any circling roots, place in new potting medium and fill around it by gently firming with your fingers. Be sure to leave about an inch headroom at the top to accommodate watering.
To keep your house plants neat and healthy, pinch or snip off any spent flowers or browned leaves. It also helps photosynthesis to occasionally clean dirt off plant leaves with a damp cloth. Or give your plants a shower.