Trouble with Tropicals?

By Melanie Mathieson
Gardening Guru

Many gardeners have houseplants known as tropicals. Many of these types of houseplants are easy to care for and seem to survive very well with just a bit of attention. But every once and a while something may pop up and you have a bit of a dilemma on your hands. Hopefully the following tips will help you solve your problem.
•I have flies that look like a cross between a black fly and a fruit fly flying around the house. What are they and what do I do?
You have classic case of fungus gnats. Fungus gnats live in the soil of your plant and feed off of fungal matter in the soil or the roots of your plants. You usually see these appear when you either repot the plant with unsterilized soil, you are overwatering or you have just brought a new plant home that was infested. At your garden supply store there are a few chemical remedies that will rid your soil of fungus gnats. Make sure you check the label to ensure what you are buying is actually for getting rid of fungus gnats and you want a formula that you apply to the soil. You want to kill the larvae in the soil before they turn into flies. Follow the directions carefully and repeat as necessary until you don’t see them anymore. An alternative to chemicals is using 1 tablespoon of Sunlight dish soap to 1 gallon of water and water your infected plants with this. This will take longer to rid the insects with this method as you have to wait until the next watering to repeat. This is one pest that I encourage you to use the chemical options of control. Left untreated they can eventually kill your plants. Also don’t overwater and if you were, overwatering before you read this column, stop immediately as most tropical plants like their soil to dry out between waterings. When you bring home new plants, repot in fresh, sterilized soil immediately.
•I have a tropical plant that just flowered – I didn’t know this kind of plant had flowers – what do I do after it is finished blooming?
Congratulations! I have had a few calls from gardener’s recently that have had their tropical houseplants bloom (snake plant/mother-in-laws tongue, aloe vera, hoyas, cacti etc.) Most tropical plants will bloom during their life cycle in the wild as this is how they produce seeds. But to have one bloom in household conditions can be quite an accomplishment. While none of the gardeners that contacted me were attempting to have their houseplant flower and they most likely were not even paying very close attention to the plants, they were nonetheless surprised when they noticed the flowers. Many tropical house plants will flower when they have the right conditions, although hard to exactly determine what the right conditions or combinations of conditions could be, as it could be any of the following: pot bound; soil has been too dry over long or repeated periods; the temperature, light conditions and or sun intensity is just right; age of the plant; etc. So if you are lucky enough to get a bloom on a tropical plant just enjoy it. One warning though – flowers on these types of plants tend to be sickenly strong and sweet scented. Not good if you have sensitivities or allergies. Once done blooming there is no need to repot the plant unless the plant is severely pot bound or the soil is in bad condition. Just hold out and keep an eye out for the next bloom – if there will be one. Good luck!
•What are the white bugs on my tropical plant?
These are mealy bugs and are commonly found on many species of tropical plants. Mealybugs are most common along veins on the undersides of leaves and at axils, where leaves join stems. Some mealybugs may also be found below the soil surface on the main stem. Mealybugs pierce plant tissue with sharp mouthparts, then suck the sap, which results in yellowing, leaf drop and poor growth. Mealybugs are soft-bodied insects, about 3/16 inch long and easily visible without magnification. Their bodies have white, waxy filaments protruding from the tail end and look as though they’ve been dusted with flour. Mealybugs can be confused with powdery mildew and sometimes are described as “tiny cottony clusters” on stems and leaves. You can control mealybugs by picking them off by hand, placing the plant in the shower and showering with lukewarm water, spraying or washing the leaves with a mixture of 1 tablespoon of Sunlight dish soap to 1 gallon of water or a combination of all the steps. If these options do not work you may have to resort to purchasing either insecticidal soap or a pytrethin based indoor insecticide. Follow the directions carefully and repeat as necessary to ensure 100% eradication of the pests.
I hope this column has provided you with tips that are useful of you want to have tropical house plants. I strongly recommend that if you like house plants, to look into adding some tropicals to your collection. Future columns will help with care and selection of some favourite tropicals for the house.