Keep your indoor plants healthy

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This article was published 24/09/2022 (1102 days ago), so information in it may no longer be current.

With nighttime temperatures dipping below 10 C on several nights already this September, one of the first tasks for many gardeners this month has been to move tropical plants and tender succulents indoors for the winter. Tropical plants can be injured when nighttime temperatures dip below 10 degrees. Tender or non-hardy succulents, however, can withstand cooler temperatures, but it is wise to bring them indoors before they are nipped by frost.

Shea Doherty, manager of Our Farm Greenhouses in Portage la Prairie, says there are key factors for keeping indoor plants looking their best until it is time to move them back outdoors next spring.

“If you are bringing a Bird of Paradise or cordyline or other type of exotic plant indoors for the winter,” says Doherty, “you have to expect that there are insects or insect eggs hiding somewhere on your plant.”

Doherty recommends spraying plants with a product such as Safer’s End-All to control a range of pests including aphids, whitefly, scale, spider mites and mealybugs, from egg to adult.

“Spray your plants for a total of three times, six days apart. This will take care of any insects that may be present,” he says. “Get as full coverage as possible, making sure the spray runs into the crevices of the leaves and where the leaf blades attach to the stem as well as the undersides of leaves, which is where insects often hide or lay eggs.”

Safer’s End-All contains two active ingredients — pyrethrin, a compound derived from chrysanthemum flowers, and potassium salts of fatty acids — and is compliant for use in organic gardening. In the United States, the product also includes an extract of neem oil; however, neem oil is not approved for use as a pesticide in Canada. Once the spray has dispersed or dried, children and pets can return to the area.

Cordyline plants, commonly known as Ti plants, are some of the most amazing plants gardeners can carry over from year to year, says Doherty.

A broadleaved plant with upright, cane-like stems and colourful, strap-like foliage with hot pink and deep purple-red tones, cordyline plants are gorgeous thrillers for annual container designs.

“Remove the annuals from your pot, bring your cordyline plant indoors and grow it as a houseplant for the winter months,” says Doherty. There are many distinct types of Ti plants but they generally prefer a well-lit room and appreciate extra humidity.

One way to naturally raise humidity levels during the dry winter months is to group plants close together. Plants release water when they transpire, which is the process of water evaporating into the air through the plant’s pores. Another method of raising humidity is to place a shallow tray of water near your plant.

“The biggest key is to not overwater indoor plants,” says Doherty. Well-drained potting mix and a container with good drainage is essential. “Avoid adding rocks or gravel to the bottom of pots,” says Doherty. Rather than improving drainage, he says, rocks in the bottom of a container prevent water from draining efficiently.

“The roots of a popular houseplant such as snake plant, for example, will rot if moisture cannot drain away properly,” says Doherty. Indoors, the snake plant has low water needs. Let the soil dry between waterings. In bright indirect light, snake plants only need to be watered twice a month but in low light, you may only need to water once every three to four weeks.

One of the reasons that snake plant — easily recognizable by its stiffly upright, variegated sword-like leaves — is always in high demand is its tolerance for both low light and bright indirect light conditions indoors. Snake plant, by the way, has undergone a botanical name change. Formerly known as Sansevieria trifasciata, it is now scientifically classified as Dracaena trifasciata.

Doherty’s favourite recommendation for an indoor container grouping is to pair a tall snake plant with dark green leaves with Philodendron Birkin, which has heart-shaped leaves and green and white stripes, and a cylindrical variety of snake plant which has round stems.

Another exotic favourite is Ficus Red Ruby rubber plant with variegated red, purple and creamy white leaves. There are many different types of Ficus which are often referred to as figs. Ficus prefers bright indirect to medium light and does well in a room such as the living room, where there are larger windows. Water when the top two inches (5 cm) of soil is completely dry.

If you are planning to bring non-hardy succulents indoors for the winter but still have not gotten around to it, keep a close eye on the weather. Succulents are more acclimatized to cooler temperatures than exotic tropicals, says Doherty, because many succulents are native to desert climates which are harsh environments with low nighttime temperatures. That said, bring your succulents indoors before the first frost.

“During the winter months, I only water the top one-quarter of the soil for potted succulents once every three to four weeks,” says Doherty. “So long as you do not saturate the soil and maintain the soil on the dry side, succulents do exceedingly well indoors. Of course, the brighter the indoor light conditions, the better that succulents will do.”

Is a windowsill too cold for succulents during the coldest months of winter? It depends on the variety, says Doherty. Succulent euphorbias (ex. pencil cactus, crown of thorns) are more sensitive to cold. “As well, if a succulent is in soil that is sopping wet, the plant will suffer next to a cold window. But if it is in a dry state like it would be in the wild, the plant will come through the winter with vigour.”

Stonecrop sedums are the hardest succulents to grow indoors, says Doherty. Gold Dust sedum, for example, which has bright yellow star-shaped flowers, sometimes gives up the ghost by mid-January. “Overwater it once and it just dies on you. It is key to keep this one on the dry side,” he says.

“By far, the easiest plant to grow indoors is Haworthia (zebra plant),” says Doherty, who grows 33 different types in a range of shapes and colours. Haworthia has low water needs and thrives in a bright indoor location.

On Saturday, Oct. 8, Our Farm Greenhouse will offer a wide selection of tropical plants and succulents in plug form, starting at $3.00 each. “We don’t do the potting up or the growing time, which is why we can offer the cost savings,” says Doherty.  Last year’s sale received a great response, he says.

“Take the plug home, fill a pot with potting mix, use your finger to make a hole in the centre of the soil that is the same size as the plug, and tuck it in very gently without packing the soil down.”

Nurturing plants indoors and watching them grow builds a strong connection.

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