Toronto Star column – published October 4, 2014
Green Plant Vacation is Over
It served you well over the summer months. Your hibiscus, dipladenia and dracaena [among others] provided a great service during the gardening season but their time out of doors is over. That is, if you want to enjoy them indoors for the off-season and have them survive to enjoy another season outdoors next summer.
Growing tropical plants out of doors has been increasing in popularity for many years now. It amazes me how many people buy an expensive flowering plant and plunk it on the patio to enjoy for our short growing season only to let Jack Frost nip it in the bud, bite the dust and end up at the end of the driveway for the ‘green bin’ truck to arrive later this month. There is no need to treat your tropical plants like a pumpkin. Alas, if you are the least bit inclined to resourcefulness, now is the time to give your tropical plants attention, which means bringing them indoors and then some.
Before you muscle your mandevilla into the TV room, I recommend that you inspect it carefully for bugs and consider repotting it. Save the extra weight to haul and topdress it once it has been located to its winter home.
You don’t have to be a graduate of Rent-O-Kill College to inspect an indoor plant for bugs and disease before you haul it indoors. Look on the leaf underside carefully and run your fingers gently over it. If it feels like very fine sand paper, your plant has spider mites. You can eliminate them with an application of insecticidal soap. Once indoors continue to spray with room temperature water, making sure that you cover the bottom side of the leaves for best effect. In time the mites will disappear as they thrive on hot, dry conditions.
The soil may have some bugs in it: gently pull the root mass of the plant out of its container and inspect it for creepy crawlies. Centipedes, millipedes, sow bugs and the like can set up shop there over the summer. They are harmless, so just hand pick them and place them in the garden where they belong.
If you notice tiny flies coming from the soil after you’ve brought it in the house, those are likely whiteflies. Keep watering to a minimum (as little as possible) as they thrive in moist soil. Consider watering from the bottom when you do water and use yellow sticky traps to catch those trying to find a more ideal egg-laying location.
While you have your tropical out of the pot, have a good look for overgrown roots. Your plant has just completed the most aggressive growth cycle of the year – that is why it looked so good out of doors this summer. Overgrown roots push their way out of the drainage holes in the bottom of the pot, circle around the surface of the soil and generally tighten the entire root mass within the pot making it very difficult to remove the plant in the first place. If this sounds like your tropical plant, repot it now while you are out of doors as this is a messy job.
Pull the soil away from the existing roots and don’t be too gentle about this. If you were pruning the top of the plant you would cut it back by up to 1/3 and think nothing of it. Do the same with the roots. ‘Scarify’ them and pull them out until you have a loose, hanging mass of roots that will be looking for a new home. Sometimes I do this with an old fork or a sharp kitchen knife. Once I had a clivia that was so totally root bound that there was virtually no soil left in the pot. In scarifying those roots I got rid of a lot of my own frustration.
The pot that you replant your tropical into should be about one size larger than the one that you remove the plant from. In other words a 10-inch pot should be sized up to a 12-inch one. Place a couple of pieces of broken pottery or large, flat stones over the hole in the pot or use a ‘pot hole’, which is a permanent, perforated round envelope filled with lava/clay rock. This opens up the soil around the drainage hole to allow oxygen in and hold the soil where it belongs [in the pot]. A ‘pot hole’ is a Mark’s Choice product.
Use quality potting mix: this is going to be the home of your valued plant roots for some time, so make it a good one. I recommend a national brand of potting soil like C.I.L. or Pro Mix. Once you have the plant positioned in its new pot, be sure to ram the soil around the perimeter of the roots using a wooden ruler or a paint stir stick. The idea is to remove any air pockets around the roots which can cause excess moisture to accumulate promoting disease.
As evening temperatures drop, the cell structure in the leaves of heat-seeking plants begins to shut down. Frost tender annuals will just die with the frost. Some will tolerate frost for a little while but others are very sensitive to the slightest amount. Tropicals are the same, only when you bring them indoors after they experience cool temperatures many of their leaves turn yellow and drop off. This is not all bad, as many will grow back again. Indeed, a Ficus benjamina generally drops leaves this time of year anyway, in response to the shortening days.
Place sun loving tropical plants in the sunniest windows that you have indoors. Note that a south facing window by mid winter will receive only 500 foot candles of natural light while the same window will have received over 2,000 foot candles back in June when the sun was high in the sky and the days much longer. I mention this so that you will understand why your tropical plants do not perform indoors nearly as well as they did while out of doors in the summer.
For most tropical plants it is best to lower your expectations and be pleased when they merely survive the long, cold Canadian winter. The metabolism of indoor plants slows down in the ‘off season’. As a result I recommend that you water much less than you did in the summer. Push your finger into the soil and check for dryness about 3 cm or an inch and a half deep. If it’s dry, water it. Don’t allow water to accumulate at the base of the pot or in the saucer as this promotes root rot. You really would not want that.
Autumn is a good time of year to inspect all of your topical plants: indoors and out. Top up the soil if it is depleted [and check that the plant does not require repotting] and clean them up for the ‘indoor’ season ahead. Green plants clean the air of toxins, add moisture during a dry period and warm up a room by just being there. Best to store it indoors than throw it away to the curb.