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Find out how to get the best from your indoor plants in winter!

Winter is a good time to focus on indoor plants, which need the right growing conditions if they are to look their best. There are ways to determine if indoor plants are situated in the best spot in your home and whether they are receiving the right kind of light. In addition, did you know that most indoor plants suffer from too much watering, rather than too little?

The shadow test

How much light do your indoor plants receive? Plants will struggle to survive if they are not getting sufficient light. Conversely, plants accustomed to the low light intensities of a cool forest will wilt in bright light. How do you decide if your plants are getting sufficient light? The first step is to perform the indoor plant ‘shadow test’. 

There are basically three zones of light in any room - bright, medium and low. Each zone casts a different shadow, and it is the intensity of the shadow which determines which plants can be grown where. To test the shadow principle, put your hand between your plant and the strongest source of light - for example, a window. Examine whether your hand casts either a strong, easily defined shadow on the plant, a vague, weak shadow, or no shadow at all. This will tell you immediately whether your plant is in the bright, medium or low light zone.

Bright light:

Filtered sun brightens most north-, east- and west-facing rooms at some time during the day, and creates a semi-circle of bright light (but not necessarily sun) around a window. Indoor plants that need bright light include: African violets, kalanchoe, cymbidium orchids, chrysanthemums, delicious monster (Monstera deliciosa), poinsettia, cinerarias (Senecio cruentus), miniature roses, the croton family, the dagger plant (Yucca elephantipes), Ficus benjamina, most palms and all succulents.

Medium light:

The medium light zone of any room normally starts a few metres away from a window. It includes the zone where your hand is able to cast a defined shadow on the plant when put between the window and the plant. Indoor plants that can survive medium light conditions include: syngonium, peperomia, the dumb canes (Dieffenbachia sp.), and most fern varieties.

Low light:

This zone includes the area of the room where no defined shadow can be cast on the plant. In other words, if you put your hand between the window and the plant there is no distinct shadow. Bathrooms, hallways and corners of rooms with south-facing windows normally fall into this zone, and very few plants can truly survive this type of environment. Try the cast iron plant (Aspidistra elatior), a peace lily (Spathiphyllum wallisii), the love palm (Chamaedorea spp.), the dragon palms (Dracaena sp.), philodendron, or one of the Aglaonema varieties.

Ficus benjamina

Kalanchoe

Spathiphyllum wallisii

Watering is key

More indoor plants are killed by overwatering than any other cause. Keeping a plant saturated with water is tantamount to killing it with kindness. Water drives air out of the tiny spaces between the soil granules and the presence of air is vital to root growth and the survival of many micro-organisms living in the soil. Boggy conditions create foul smelling soil, rotting roots and the ultimate death of a plant.

How often?

So how often should you water? An indoor plant should be allowed to become moderately dry between waterings. Rather soak them thoroughly every 10 days than give them a little water every few days. A little water only penetrates the top few centimetres of soil and will rarely get down to the roots at the base of the container.  A thorough soak will reach all the roots and benefit the plant in the long term.

Remember too, that in winter, heaters often cause the level of humidity inside a home to drop.  Indoor plants such as ferns and palms react to the low humidity and the tips of their leaves will go brown. To combat the problem, keep indoor plants away from heaters and place large plants on a tray filled with pebbles and water. The water will evaporate, creating a microclimate of high humidity around the plant.

When?

The best time to water plants is in the morning when they still have the daylight hours to utilise the water.

With what?

With indoor plants, remember the adage, ‘cold water kills’. Avoid using cold water for indoor plants, especially in cold weather. Use tepid or lukewarm water. Your plants are able to absorb it easier, and it will not send them into a state of shock.

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