Answers to Your Questions Part 3

Answers to Your Questions (Part 3)

Many of you have e-mailed me your gardening questions. Here is a third and final article entirely dedicated to answering some of your questions.

• Also read: Answers to Your Questions (Part 1)

• Also read: Answers to Your Questions (Part 2)

Q Ever since I brought my hibiscus into my house this fall, it has been infested with small whiteflies. Can they be eliminated or do I have to dispose of my plant instead? Thank you for coming to my rescue.

Mme bagreau

Hibiscus 'The Path'

Photo courtesy of Monrovia Nursery

Hibiscus ‘The Path’

R When hibiscus are grown outdoors, they rarely fall prey to insects and disease. Some aphids can sometimes attack them and cause them problems. Usually indoors, hibiscus are most easily attacked by insects, especially whiteflies.

The whitefly, commonly called white fly, is a very small insect, 1 to 2 mm long, whose body and wings are covered with a thin layer of whitish wax. There are two main species of whitefly ravaging our climate, the greenhouse whitefly and the tobacco whitefly.

A close relative of the aphid, the whitefly consumes the sap of several hundred species of plants, particularly tropical houseplants such as hibiscus. This insect is also the carrier of certain viruses.

There are several generations of whiteflies per year. The adult lives about 45 days and lays up to 200 eggs, which usually hatch after a dozen days. The ideal temperature for the development of this insect is between 18 and 24°C.

Installing yellow sticky traps can detect the presence of this insect and provide some control. However, if you notice that shaking the plant causes a lot of whiteflies to fly away, this obviously means that there is an infestation and you need to intervene more vigorously.

We must first isolate the affected plant to prevent it from infecting others. Then quickly cover it with a plastic bag—a bag over the dry-cleaned clothing is usually sufficient. This way the whiteflies cannot escape and can then be eliminated by spraying an insecticidal soap on the plant. Spray this product with a sprayer every two to three days until the problem is resolved. Leave the plastic bag in place for an hour or two after each spray. You can also vacuum the foliage of an infested plant. This way the whiteflies are caught before they can fly away.

If several of your plants are infested with whiteflies, you may consider using certain insect parasitoids such as Encarsia formosa and Eretmocerus eremicus. These microwasps, harmless to humans, lay their eggs on whitefly larvae. There is also a ladybug species called Delphastus catalinae that is particularly effective at controlling whitefly populations.

Q I heard that you can grow ginger in a pot indoors. Can you please explain me how to do this?

Mme Dube-Gagnon

Ginger from the pot

Photo courtesy of Bob’s Market and Greenhouses

Ginger from the pot

R To grow your own ginger, the technique is quite simple. First you need to buy a plump ginger rhizome from a supermarket or health food store. Then plant the rhizome in a large container, 35 to 40 cm in diameter, filled with a potting mix of compost and sphagnum peat moss. Make sure that the rhizome is placed on the surface of the earth so that its upper part is slightly above the ground.

Planting ginger is best done in spring or early summer, but can be done at other times of the year. However, it is important not to leave your ginger outside during the cold season. Therefore, as soon as autumn arrives, it is imperative to bring your ginger plant indoors and place it in a light spot. The harvest can take place five to six months later.

Ginger is a tropical plant that loves warmth (22 to 25°C) and constant humidity. However, to prevent it from rotting, you should not water it too much before it has taken root. During this time, watering should only be done when the soil surface is dry. You can water more when the stems are well developed, ie once or twice a week.

Q I saw small plum trees called chums on a fruit tree grower’s website. I want to plant one in my garden. Is this species easy to breed? Is it susceptible to diseases like other plum species?

Mr Durivaux

Photo courtesy of Alberta Home Gardening

R There are in fact different varieties of small fruit trees, born from hybridizations between the plum tree and the cherry tree. The delicious and very sweet fruits of these trees are slightly larger than cherries and slightly smaller than plums. They are called cherry-plums or chums (ch-erry + pl-ums) in English.

All hardy for zone 3, ‘Convoy’, ‘Kappa’, ‘Manor’, ‘Opata’ and ‘Sapa’ are the most desirable cultivars. These small trees or large shrubs are generally less than 2 meters tall and are considered less susceptible to black knot, a disease that afflicts plum trees very often.

Cherry plums need humus-rich, light, cool, well-drained soil. Avoid pruning these plants too frequently to avoid promoting the spread of disease. In addition, like most other plum varieties, they are self-sterile, so it is important that two specimens are not planted far apart in order to obtain fruit.