Now that the winter is closing in, it’s a good time to turn our attention to the plants that live with us. In colder climates indoor plants provide us with blossoms and enough green that we don’t completely despair in the depths of winter. They also keep us healthier by filtering pollutants from the air we breath. So let’s talk about how we can return the favor and keep them at their best.
As you would guess, there is no one answer for all plants. Each plant has its own requirements and won’t thrive, and certainly won’t flower, unless you make sure the light is appropriate for the plant.
Here are the categories of light that are commonly referred to:
- Direct sun — a sunny windowsill usually facing south or southwest. Sunny most of the day with direct sunlight on the plant.
- Bright, or indirect sun — a room where there is bright sunlight for most of the day from a east- or west-facing window, or a south-facing window with filtered light (through trees or other light shade).
- Average — a north-facing window, or some morning sun from an east-facing window. Might also be a location farther from the windows in the sunny or bright categories.
- Low — a shady location near windows shaded by trees or far from a bright window.
If your plants become spindly, won’t bloom or have yellowing leaves you can suspect too little light. On the other hand if your plants wilt, the leaves fall off or have brown patches, it could be an indication that they are getting too much light. This link will give you an idea of what light levels some common houseplants will tolerate.
Most houseplants like a temperature between 70 – 80 degrees in the day and 60 – 68 degrees at night. A nighttime temperature that is 10 – 15 degrees cooler than the day is ideal.
Too high or too low temperatures will cause leaf drop, spindly growth and slow to no growth. Also be careful that your plants aren’t getting blasted with hot air coming from heat registers.
Water & Humidity
And speaking of indoor heating, it sucks moisture out of the air and your plants. Keep an eye on your plants’ moisture levels when you start using your heat. Most need less water in the winter, but being near a fireplace, stove, or other heat source could increase their need for water.
If you have humidity-loving plants like orchids or ferns, keep them away from cold or hot drafts. Place them in a tray on a bed of pebbles and keep it filled with water. They’d appreciate an occasional misting too.
As with light, each plant has its own requirements, but in general water your plants when the top layer of soil is dry. I just stick my finger in the dirt and if it feels dry I water the plant. Or, you could get one of those inexpensive soil moisture meters at your local garden center and keep your hands clean.
After a while you’ll get to know which plants like to watered more or less frequently. Don’t wait until the plant wilts to water it. This is a major stress on the plant and it will never do well.
Here’s a tip for watering orchids: put 2 – 5 ice cubes in the pot (depending on the pot size) once a week.
We like organic fertilizers like fish emulsion (can be a little smelly, but works well) and seaweed extracts like Stress X or Neptune’s Harvest. Mary Beth just got some TerraCycle Plant Food, which is an organic foliar spray, that she’s going to try.
Follow label directions for whichever type of fertilizer you select. Most plants will need to be fed every 2 weeks when they are actively growing, usually from March to September. You can give most plants a diluted feeding, about 1/2 to 1/4 strength, once a month in the winter months. Remember to be consistent in your feedings. Your container plants rely on you for their nutrients.
Pests on indoor houseplants can be tricky. Well-cared for plants generally won’t get pests, but if you have a serious infestation you could be in big trouble. I had a nice collection of orchids that I had to get rid of as a result of mealybugs — horrid little creatures. My daughter gave me her beautiful orchid when she moved. It had a few mealybugs on it and against my better judgement I decided to rescue it. I isolated it and swabbed the bugs with alcohol, but they never went completely away. Then I discovered that my other orchids had been infested even though they were in another room. I struggled with them for months, but could never get rid of them and so I have to start over with new plants. Very sad!
Many problems can be solved by washing bugs off the leaves with a water spray — putting them in the shower works well. If that doesn’t work, try a mixture of water plus 1 tablespoon of mild liquid soap like Ivory or Dr. Bronner’s Pure Castile Soap. Put your plant in the tub or shower, spray with the mixture, then rinse with lukewarm water. Be sure to follow up with a second treatment in a couple of weeks. Insecticidal soap is another good option.
Here are the most common bugs and what to do:
Mealybugs are white and wooly, like little cotton fluffs. Be sure to check for them under leaves and in crevices and joints. Start with the soap solution, keep checking to make sure they don’t come back. You may have to take the plant out of the soil, rinse the roots and repot with fresh soil to get rid of them. Another remedy is to wipe the leaves and crevices with alcohol.
Fungus Gnats are little black flying insects. You may notice a little cloud of them when you water your plants or you might see the larvae wriggling in the soil when you water. They can often be killed by letting the soil dry out between watering. You might also try those yellow sticky traps, which can also help with thrips and whiteflies. Some say that sprinkling the soil with cinnamon helps.
Scale are round, brown hard shelled-bugs that are found on the underside of leaves and on stems. Wash the plant with the soap solution and rinse well. They are a little tough to get off, you may need to scrape them off with your fingernail.
Colorado State University has a really good article and printable fact sheet that will help you identify and treat pests on your houseplants.
One last tip is to check the soil in your pots. Plants that have been in the same pot for a long time can use up the soil. So if your soil level is low, or you notice that the roots are coming out of the bottom of the pot, make a note to repot those plants in the spring.