Indoor Plant Care & Advice
Advice and tips for growing houseplants in Christchurch, NZ
Potting and drainage — Happy roots first
All potted plants will prefer water to drain through the pot and to be planted in a potting mix blend which is perfect for them. This means using appropriate sized pots with plenty of drainage holes and sometimes blending your own potting mix to suit the preference of a particular plant. Choose a pot which is in proportion to the plant, planting into a pot too big will stunt the growth of your plant as the soil won't dry out. Ensure that the pot you are planting into has plenty of drainage holes and that you have a saucer or a nice pot without holes to protect your indoor surfaces from water which runs through.
For cacti and succulents which really like to dry out, I add a few cups of fine pumice to a bag of organic potting mix and for ferns and orchids which prefer to stay in wet soil for longer, I add a few cups of fine NZ Sphagnum moss. To both of these mixes I sometimes add vermiculite which helps to aerate the soil and makes it a bit lighter. Repotting is best to do from late winter to early summer as most indoor plants are sermi-dormant (not growing much at all) over the coldest months in Christchurch.
Watering — Go with the seasons
Generally I water my indoor plants at home weekly in the summer, fortnightly in the shoulder seasons and monthly in the winter. I say 'generally' because when it comes to weather; no season is the same and no week is the same. The golden rule for watering is to water when the soil is dry. You can stick your finger in an inch or two to see if it is dry or check the weight of the pot. A pot full of dry soil will be a lot lighter! If the soil never gets the chance to dry out then the roots are likely to rot. I tip water quickly so the whole pot is covered and can drain down evenly. Don't leave pots sitting in wet saucers, especially in the winter when it could be too cold for it to evaporate.
Over the warmer months when your plants are growing is when they will love some liquid fertiliser. I use compost tea, seaweed tea and worm castings diluted into my watering can to water and feed simultaneously. This mix feeds the plants and improves the soil quality as it increases microbe density and diversity. These microbes work with the roots in in the most amazing way in organic soil to help make nutrients available to the plant when they are needed.
Placement — Can I put a plant here?
Tropical plants work well in our homes because most of them come from the floor or sub-canopy of the rainforest where the light levels are similar to that found in our homes. Cacti and flowering plants need a lot of direct sunlight but most houseplants would prefer bright indirect sunlight. This can be found in any room with a window and can be enhanced by the aspect and light being reflected off bright coloured or shiny floors, walls and ceilings. It's worth noting that early morning and late afternoon direct sunlight is much softer than direct sunlight in the middle of the day. Like all potted plants we are trying to give them their preferred conditions so they will grow healthy and bold for us.
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Plants become accustomed to the light level and a major change like being moved from a shaded spot into direct sunlight can burn the foliage (even if this plant can handle direct sun once it has become accustomed to it).
In nature the conditions for a plant change very slowly therefore we try to make slow changes to the conditions for our pot plants. For example if I move a Rubber plant from inside to outside in the winter it will probably die from the cold shock but if I put that same tree outside in the summer and left it to adjust too the cold over the months as winter comes then this tree will handle the cold. It's just the initial sudden change which can cause fatal shock to some plants.
Pests — Knock 'em out
The most common pest to plague my plants is definitely mealy bug. They pop up as white fluffy looking stuff on the leaves and gather around new growth tips. They grow about as big as an ant and at that stage they look like a living fossil. Scale bug and spider mite are the lesser evils of the pest world for me but I treat them all the same way.
I use Stylet oil which is an organic mineral oil and is really effective as a spray to eliminate existing bugs and protect the foliage without hurting the plant.
The flying invaders of the soil which look like sandflies are fungus gnats. They feed on the organic material in the soil and will thrive in wet soil and pots with root rot. Treating them begins with letting the soil dry out as much as possible then using an organic oil like Neem or Stylet diluted into your watering can for the next few times until they are gone.
Slow & steady wins the race
Start with a few plants and grow your collection slowly. The care of the plants you bring into your life will become part of your lifestyle. Some of the easiest houseplants include yukkas, spider plants, peace lilies and aspidistras. More on plants coming soon.