Potted plants are among the most popular features of any garden or home.
However, because these plants are growing in an artificial and controlled environment, they require a little more attention than the ones growing from the ground. This includes repotting – either because the plant needs a potting mix refresh or it has outgrown its existing pot.
Knowing when to repot may not be an exact science, but there are several signs you can look out for that may help. These include:
A visible drop in potting mix level
Poor plant growth, with leaves losing their lustre and changing colour
Clivia roots are pushing out of the potting mix
Mix appearing sandy and compacted
Mix shrinking away from the sides
Water running straight from the top to out from the drainage holes
Visible plant roots on the surface or emerging from drainage holes
Plant looking oversized for its pot (plastic pots may bulge or split)
Water overflowing in the pot, with no absorption by the plant.
Besides these, you should also consider how long your plant has been in the same pot. If it has been more than two years, then it’s generally time to replace the pot.
Understanding potting mix
Knowing when to repot your plants is also largely dependant on when you need to replace your potting mix. This is the first thing you should look at replacing when there is a dip in your plant’s freshness and overall vigour.
It’s worth knowing a little about modern potting mixes as this will help you on the pathway to potted perfection.
Today, potting mixes are more commonly known as growing media, instead of soil.
In the past, mixes did contain mined or excavated topsoil, which would be blended with multiple materials to create a balance between drainage and moisture retention. Now, they contain a blend of materials like graded Pine-bark and coir chips and fibre, along with controlled-release fertilisers, trace elements and wetting agents. Vast amounts of research and care go behind getting the mixes just right. Matted roots cover the surface of this ginger
These mixes can also be very specific in their blends, with bagged mixes created for special purposes. For instance, mixes specially tailored for growing citrus foods or herbs.
When a plant comes to you from a grower, it will typically be in mix that has been specifically tailored to that plant. It’s one of the reasons why plants growing in nurseries always look so amazing.
Over time, this mix becomes depleted of nutrients required for root development and water and air movement. This is because the bulk of a potting mix is made out of elements that naturally compost and degrade because of microorganisms in the mix.
Potting mix lifespan
Potting mix manufacturers recommend that you repot your plants every two years or so. This is a general recommendation. There are a lot of other variables which may impact the quality of your mix.
Here are some factors to consider when deciding when to replace your potting mix:
The type of plants. Vigorous plants tend to fill their pots faster and also consume nutrients more readily. This can quickly lead to overcrowding.
Excess water. If your pots are watered too frequently, the materials in the mix may disintegrate faster, leading to nutrient depletion.
Lack of water. The structure of your mix may be damaged if your pot is too dry, killing microorganisms.
Fungal outbreaks. The fungus decomposes the mix, making the latter water repellent.
Displacement. This is when the potting mix is physically removed from the pot, often due to excessively harsh watering or the presence of ants.
Need more help with repotting your plants?
Check out our step-by-step guide on How to pot a plant. You can also post a question by clicking the Start a discussion button and we will be happy to assist.
For more inspiration
The Bunnings Workshop community team has also shared these helpful guides related to creating your own planters: