Plants are now an integral part of our interior spaces, but if questions directed to the Growing Friends are a guide, they are also a growing challenge. Here is some advice for indoor green success from one of our wonderful Growing Group volunteers, Greg Lamont.
All over the world indoor plants are back in fashion and for good reason. Plants bring life and calmness to indoor and outdoor living spaces and are proven air purifiers. Growing plants indoors is often the first attempt at gardening for many people and it can be very disheartening to watch your plants die.
Atmosphere
A comfortable environment is important, and a good rule of thumb is if you feel comfortable then it’s likely your plant will – humid fresh air, temperature in the 20s, out of a draught and medium to bright light during the day. Many of the plants that thrive indoors have their origins in rainforests where they grow in warm conditions with dappled light.
Kentia palm (Howea forsteriana) are native plants suitable for indoors.
Light
Matching your plant with the correct light requirements is important for plant survival. Plants require bright light (not direct sunlight) in order to grow indoors. Less light may mean they survive but put on little growth.
Plants with dark leaves will tolerate less light than those with pale green or variegated foliage. You might need to try various spots in your house and change things around through the year as the sun angle shifts with the seasons.
Palm-lily (Cordyline stricta) is a tall native plant that can be cut back.
Water
Poor watering is one of the most common causes of failure. Indoor plants are best watered in the kitchen sink. Remove them from their decorative outer pot and give them a good drenching with tepid water, allowing them to drain thoroughly.
In warmer months this should be done weekly but in cooler months reduce to maybe twice a month unless you have heating, in which case it should be more often. Most plants benefit from a slight drying out between watering. Use your finger to test whether the soil is moist or dry in the top 2 cm.
Watering too frequently results in overwatering, leading to sick plants. Water-logging can kill roots so if you have your plant sitting in a saucer to protect surfaces of tables or shelves raise the pot above the saucer with some pebbles or gravel to keep the roots away from water.
Button orchid (Dischidia nummularia) is actually part of the Milkweed family, not an orchid.
Nutrients
Indoor plants benefit from monthly fertilising with half-strength soluble plant food from October to May when they are in active growth.
Staghorn, elkhorn or bird's nest ferns can tolerate neglect if protected from the afternoon sun.
Pests
Check for any pests that could be hiding in leaf junctions or near soil level. Scale (brown or white), which looks like little scabs; and mealybug, like fluffy white cottonwool, are the most common pests of indoor plants. Both suck the sap and slowly debilitate your plant.
Their sugary exudate can also attract ants. A safe way to kill the pests is to dab them with a cotton bud dipped in methylated spirits.
Umbrella trees (Schefflera actinophylla) will easily grow ceiling height indoors.
Dust
Dust can be an enemy to indoor plants so wipe the leaves with a damp soft cloth or wash them down in the shower. If you need to give your indoor plants a rest outdoors make sure they are protected from any direct sun.
The Growing Friends has a small range of hardy plants suitable for growing indoors. These include Peperomia obtusifolia, varieties of Japanese tree ferns (Asplenium), Crocodyllus fern, some Rhipsalis and several Begonia varieties with colourful or patterned leaves.
Learn how to propagate yourself
Visit the Gardening at Home section of our website for more expert advice.
The Growing Friends, are a volunteer group who run the Nursery for the Foundation & Friends of the Botanic Gardens.