Your tropical plants are begging for some TLC
Mark Cullen: It’s time to clean, trim and/or re-pot indoor plants
What does a poinsettia require to stay alive through the holidays?
Poinsettias are a popular holiday plant and easy to care for. You will get the most from your poinsettia by:
You have battened down the hatches in your garden and waved goodbye to the season. Time to sit down and read a good book. Not so fast.
Remember the tropical plants that you brought indoors in the fall? The hibiscus, oleander, mandevilla vine and the herbs that are now dropping leaves on your living room floor? They could use some TLC right about now.
You’ll notice that as the temperatures out of doors, fall so does the humidity in your home, condo or apartment. Yet most of our tropical plants come from a warm, southern place and their native habitat is quite opposite that of your current, pre-winter home environment. Your aspidistra is wheezing and having a hard time inhaling — you just can’t hear it.
The first thing you should do is clean the leaves of your broad-leafed plants using insecticidal soap, which is more soap than insecticide. Spray some on a clean cloth and wipe down your plants’ leaves. (Do this while watching a TV show that does not demand your full attention. In my experience this would include all of them, except maybe Jeopardy. You really have to concentrate to get the full benefit of Jeopardy.) Wipe both sides of the leaves thoroughly to remove dust and grime.
Small-leafed plants, like the famous ficus benjamina or ‘Weeping Fig’ (so named since it really is not very happy in Canadian homes during our winter months), can be cleaned by simply spraying the leaves with the insecticidal soap solution, top and bottom.
Think, once again, about the natural habitat of your Dumb Cane (dieffenbachia): Warm. Humid. Near the equator where there is lots of light.
It is natural for most indoor tropical plants to lose some leaves this time of year, especially if you had them outside for the summer. The intensity of natural light in our homes right now is very low. A south-facing window in the summer may be exposed to up to 2,500 foot-candles of light on an average summer day. The same window this time of year meets about 500 foot-candles.
It is not just the day’s shortened length that causes the sun to lose power in winter, it is the low angle at which the sun sits when it does shine. The shortest day of the year, December 21, is only two weeks away. And it was shortly after this day when ancient Druid priests, using a golden sickle, would cut mistletoe from a holy oak tree. The mistletoe cuttings were delivered to the people and hung inside to ensure fertility, bring about love and ward off witchcraft.
Meanwhile, during the time the Druids would be cutting mistletoe, your hibiscus is losing its leaves. Don’t be alarmed — the tree/shrub needs to lose leaves in order to rejuvenate itself.
I cut my leafy tropicals back this time of year by at least a third. Reach into the body of the plant and remove some of the woody, less leafy growth with a sharp pair of hand pruners. This will encourage more growth from the middle portion of the plant, producing a thick, healthy appearance and more even flowering, in the case of the hibiscus.
Generally, I don’t fertilize my tropical plants this time of year. They are not growing as they did in the summer, so they have no need for the nutrients. An exception is the African violet which I fertilize with half strength 20-20-20 water soluble fertilizer every two to three weeks all year round.
A tropical plant has its own way of telling you whether you need to re-pot it. Look for roots that are growing through the surface of the soil. If you can’t see any, scratch the soil with your fingers to see if they lurk just beneath the surface. Ah ha! There they are. Now tip your plant on its side and look for roots growing out of the drainage holes in the bottom of the pot. If you don’t see them, feel through the drainage hole. If you find roots, it’s time for either a bigger home or a root pruning.
If you choose to re-pot, pull the plant out of the pot, roots and all. Chances are, it is stuck in there with the roots creating pressure against the inside wall of the pot. For a large tropical plant this could be a two-person job. No worries, you can’t hurt the plant.
Once released from its undersized pot, pull the roots of the plant apart — and be ruthless. A pair of scissors may be called for. Or a small, sharp kitchen knife. The idea is to give the roots freedom and convince them that it is indeed time to put roots down into a new home. You are pruning the roots as you would prune the top portion of the plant and for similar reasons: to thicken them and encourage new growth.
Be sure not to buy cheap, poor quality potting soil. Look for a quality mix that is weedless, light, open and one that does not contain nutrients. Many of the potting mixes created for summer containers contain a slow release fertilizer, which is well and good, but not for your valuable indoor tropicals that need a rest after the trauma of re-potting. A good, gentle watering after the re-potting is all that is needed.