In the garden: My mandevilla vine is waiting to hear its fate
If plants indeed have feelings, the mandevilla vine I’m growing in a container on the patio must be nervously wondering if I’m going to bring it indoors before the end of the month.
And it’s not alone. I suspect there are quite a number of similar vines around town that are anxiously awaiting their fate. Will they be abandoned, tossed on the compost heap, or only considered the morning after a frosty night? By then it will be too late.
Many gardeners thoughtfully bring these plants indoors before temperatures at night fall much below 10 degrees, thereby relieving them of any worries. But then the leaves turn yellow and fall off within days and the plant is tossed anyway. It’s a pity, as most can be overwintered successfully.
As for the falling leaves, this is what they do in fall and to some extent, even tropical plants will drop a few leaves. Lower light levels found indoors simply compound the problem. In some cases the plants don’t lose any leaves, even appear to flourish for a while, then it begins — a yellowing leaf here and there, and soon the vacuum cleaner is clogged with them.
The leaf drop can be due to the change in conditions or it could be insects, insects that love to spend the winter in a cosy living room where, unlike outdoors, there are no predators to limit their enthusiasm for reproduction. Aphids, mealy bugs, and white fly are among the usual suspects, plus a few soil dwelling critters that may or may not be harmful to the plant.
Here’s what to do before bringing your plants indoors — and this goes for all plants making a move.
First, wrap a plastic bag around the pot and tape it to the main stem. This is so the soil doesn’t become over saturated with whatever you use to spray the leaves. The spray may take care of a few soil pests, but too much isn’t good for the plant. It has been suggested that soil pests can be controlled by standing the pot in pail of warm water for 20 minutes. I’m not sure how effective it is, but if it’s hot enough to kill bugs, it may also broil the roots, so be careful.
As for the spray, you can use an insecticidal soap formulated for houseplants, or mix up your own soap spray at 20 parts water to one part pure soap. Horticultural oil is also an option if used according to directions.
When spraying, ensure that all foliage and stems are completely covered, over and under. The sprays are not supposed to harm leaves, but I always advise caution. Sometimes it’s wise to test on a couple of leaves first, although it will take a few days before any damage shows up. To be on the safe side, I like to rinse off the solution after about 15 minutes. Repeat the process about a week later to ensure you get all the pests. If you have to do this after you’ve brought the plant indoors, your plant will be more than happy to share a gentle shower with you (Watch the temperature and skip the conditioner!).
Once indoors, depending on how large the plant has become, place it in front of a sunny window, but avoid the hot air register as these plants like high humidity — regular misting or placed on a water-filled pebble tray. If conditions are right, it will continue to bloom for some time.
Alternatively, mandevilla can be cut back to about 30 centimetres, which will also take care of many pest problems. If it continues to push out new growth, fertilize lightly, otherwise none until normal growth resumes, usually in mid to late February.
If you aren’t able to provide optimum conditions, the alternative is to allow the plant to go dormant in a cool room where the temperature stays around 10 degrees. Water only enough to prevent the soil from drying out.
Now, go give some reassuring words to your mandevilla (also known as dipladenia) — and keep a close watch on the weather forecasts.
