There are three things plants need to survive: water, air, and light. Most also need some sort of plant growing medium in which to put down their roots, and for indoor plants, that’s normally potting mix.
Add feeding to the mix and you have 5 key ingredients for success.
It sounds obvious, but watering can be tricky for indoor plants. It’s not like outside in the garden where rain and drainage are normally a given. For indoor plants, the ability to have a drink and a wash comes down to you, the plant parent! So, think about why and when you get thirsty, and translate it to your indoor plants.
If it’s hot or windy, you need extra water, so for plants that means warm weather, but also air-conditioning or heating. If you’re doing heaps of exercise, you need more, and while plants won’t be going for a run, their spring growth spurt needs to be encouraged with extra juice in their tanks!
It’s best to water your plants outside with a hose or in the shower, where you can give them a drench and a wash, every month. Top up in between times throughout the warmer months by adding enough water that your plants start leaking, so be prepared with a saucer underneath to catch the drips, but always lift your plant out of this excess water by placing some pebbles or pot feet under the pot so that the drainage holes can breather. Do this whenever your plant needs it.
This can be ascertained with a watering gauge, your finger (does it feel dry beyond your first knuckle when you poke it into the soil) or if your plant is dropping and showing signs of stress.
Plants actually ‘breathe’, even though they use their roots, stems and leaves rather than lungs to absorb gases. Plants need oxygen for respiration, put also ‘breathe out’ oxygen during photosynthesis as a by-product.
What this means is that air has to be able to get to the places its needed. That’s why leaves should be cleaned down with a damp cloth or rinsed off in the shower, as it stops the stomata, or the breathing pores on leaves, from becoming clogged with dirt and dust. It’s also why most plants need to be free draining (see note above) as the roots also need to be able to ‘breathe’ to get the air they need as well as the water.
Sunlight, or artificial ‘grow’ lights are needed for plant growth – even indoor plants. The ‘rule of thumb’ is that if you need a light to read, it’s too dark for plants to grow well too, unless you can provide them with horticultural LED lights or fluorescent full spectrum or “cool white” bulbs. If you want to help your plants by choosing a light bulb that suits their needs, they need blue and red wavelengths.
Most people just pick a spot that’s bright enough and rotate their plants a ¼ turn every few weeks so that they grow evenly, or buy two plants and have one inside and one outside in the shade, and swap them around every fortnight so that they get enough light. If you’re worried about how much light you have, choose a low light tolerant plant like a peace lily or devil’s ivy.
The other light issue can be when plants are getting burnt by the heat that comes from the light waves being changed when they come through glass. If that’s happening, just bring your plant inside a touch more and it should enjoy the light without the leaf burn!
4. Plant Growing Media
Australia has some of the best potting mixes in the world, provided you get the ones with the Australian Standard 5 ticks on them. The red ticks are the premium version and contain fertiliser and water storing crystals. If you have plants in pots, grow them in potting mix for the best results.
Never use soil as it simply doesn’t have the drainage and aeration properties need for good growth, and never use potting mix without the standard, as it can be the cause of nitrogen drawdown, making your plants yellow! Also, due to the make-up of them, if it dries out, it can become water repellant (hydrophobic) will need to be completely saturated to properly work again, which means soaking in a bucket or sink for about 30 minutes.
Indoor plants can also become rootbound and should be repotted every few years into a slightly larger pot, or root pruned and put back into the same pot. This is best done at the very end of winter and beginning of spring when the roots are actively growing and will settle back into their new home with ease.
Indoor plants should be fed when they are actively growing, which is during spring and summer. Regular feeds of liquid fertiliser and a once-a-year application of slow release are the simplest methods.
Choose an organic, nitrogen rich feed for your foliage plants and apply a specialized fertiliser for flowering plants, like orchids and African violets which have specific needs.
If you’re growing cacti and succulents indoors, avoid using too much nitrogen on your plants as this can promote weak, soft growth. Be careful not to fertilise in winter, as you can burn plants, as can overfeeding, so always use fertiliser as per instructions.