Indoor plants looking a little sorry for themselves? Before you bin that limp straggly old fern, ask yourself if it needs is a little feeding, moving to a better pot or a spray mist of its fronds
Tips for growing and watering an indoor plant
Plants indoors in New Zealand need looking after just as they do when growing outside. Sometimes more so. Our houses and buildings are artificial environments that can be dusty, harshly lit and lacking fresh air – not ideal conditions for living plants. Fortunately it’s not that difficult to modify those conditions, or choose species better suited to them. Add some regular TLC to the equation and your revitalised indoor plants will enhance the places where you live and work.
Maybe they just need a good feed…
Some people regard indoor plants as inanimate objects like a vase or lamp. Plants have needs like all living beings and food is one of the most crucial. Feeding requirements vary depending on the type of plant and how long it’s been in its pot. Recently purchased plants should have nutrients in the potting mix but these will gradually become depleted over a couple of months.
The most convenient forms of fertiliser for house plants are slow-release granules, soluble powders or liquids. Feed plants once a month only during their growing season (usually the warmer months) using a standard fertiliser. You could also try fertilisers specially designed for leafy plants or to encourage flowers, but check with your local garden centre if unsure what to use.
Plants need to stay hydrated
Watering varies hugely depending on the type of plant. Cacti and succulents are desert plants and therefore need very little water, whereas ferns and many leafy plants require plenty of hydration. The temperature of your room will also affect watering needs. When the heating is on full blast your plant will lose as much moisture as it would in a sunny position on the window sill.
As with feeding, when plant growth slows down they need less water. The type of pot you use is also a factor. Plastic and glazed pots lose moisture more slowly than terracotta, for instance. Check your potting mix, too. Some are fast draining, designed for plants that need little moisture, while others contain water-retaining materials. The best way to check if a plant needs water is to poke your finger into the potting mix. If the mix is dry, water the plant.
Perhaps they need repotting
As a plant grows, its roots take up more space in the container and the potting mix is used up. Most house plants need repotting once a year, ideally at the beginning of the growing season. Once they reach maturity, which can take several years depending on the species, repotting can be done less often although fresh potting mix will need to be added regularly to the existing pot. If several roots are poking out of the bottom of the pot or it feels very tightly packed, it’s time for a slightly bigger pot.
Before repotting, water the plant and leave it for an hour, then tap the sides of the pot to loosen the rootball or slide a knife between it and the side of the container. Use gloves and keep one hand on the plant stem to avoid breaking it as you pull it out. If the plant is very root-bound you may have to break or cut the pot. Cut off dried or rotten roots, untangle those that have formed circles and trim if necessary.
Choose a larger pot and fill the base with sufficient potting mix so that the base of the plant stem sits a few centimetres below the rim (not too high or watering will be difficult). Place plant in position and add potting mix, packing it in gently as you go around the plant, until the surface is level with the stem’s base. Tap the pot lightly on the ground to settle the mix and get rid of air pockets. Water well.
The light might not be right
Some flowering house plants – such as geraniums (aka pelargoniums), kalanchoe, hippeastrum and spring bulbs – need plenty of light, as do succulents and cacti. However, avoid positioning any indoor plants in full sun behind a window as the heat can scorch their leaves and dry out the potting mix. Most leafy green plants prefer varying degrees of indirect light – neither direct sunlight nor dense shade.
Check the humidity
Dry air will cause the leaves of indoor plants to shrivel or brown on the tips. Some plants need more humidity than others, particularly those with thin leaves. Spraying with a fine mist once a day will help, or you could stand the pot in a shallow dish of water filled with pebbles. The water level should remain below the pebbles to avoid making the mix too wet.
Those leaves can’t be left feelin’ dusty and musty
Keeping leaves clean not only makes plants look better, it also improves their health as they are better able to absorb air and moisture through their leaves. Some people regularly pop their house plants into the shower or you can take them outside. The water should ideally be at room temperature, not cold. If your plant is too big to move, sponge leaves with a damp cloth. Clean hairy leaves with a soft brush.
Carol’s top 10 easy-grow indoor plants
1. Spider plant
3. Peace lily
4. Rubber plant (Ficus elastica)
5. Weeping fig (ficus benjamina)
6. Parlour palm (or try a kentia)
7. Dracaena marginata
8. Mother-in-law’s tongue
9. Devil’s ivy
10. Donkey’s tail
Indoor plant care tips
Feeding and watering may not be the solution for a sickly plant. First check whether it’s too hot or cold or it might need repotting.
Words by: Carol Bucknell