Making your own potting soil is a great way to ensure that there are no nasty chemicals or fertilisers that you wish to avoid. But, it can also save you money, which is never a bad thing.
Before considering making your own potting mix, it is important to understand what type of soil you need. If you are growing from seed, this may require something quite different than potting established plants.
- If you want to buy potting soil instead, read our guide to buying the best quality potting soil for your plants.
Once you understand what type of soil you want to make, use the guide below to make the perfect potting soil mix for your plants.
Note: A “part” can be whatever you want, depending on the volume of soil you want to make.
Basic potting soil (for most plants)
- 1 part coconut coir
- 1 part vermiculite (or coarse sand)
- 2 parts sieved compost
- 1/2 cup worm castings or Vermicast
Soak your coconut coir, if necessary. Mix the soaked coir and vermiculite (or equivalent) in a large container. Next, add the compost and Vermicast to the mix. If you decide to add nutrients to your potting soil, this is when they should be added to the mix. A slow release organic fertiliser is recommended for this purpose.
Basic seedling potting soil
Seeds need a light potting soil with lots of space for roots to grow and air to circulate. This type of soil lets sunlight and warmth get to the seeds to allow germination. To make a basic seed potting mix, you will need:
- 2 part sieved coconut coir
- 1 part sieved compost
- 1/2 part perlite
- 1/2 part vermiculite
Soak the coconut coir, if necessary. Next, mix the coir and the compost together in a large container. Stir in the perlite and vermiculite.
Potting soil mix for cacti and succulents
Cacti and succulents require potting soil that provides a lot of drainage and doesn’t hold excess moisture. Once you have made the basic potting soil above, add the following ingredients:
- 3 parts basic potting soil
- 2 parts coarse sand
- 1 part perlite
Very simply, just mix everything together evenly and thoroughly.
Tips for all potting soil mixes:
- The coconut coir may come in a block. If so, sit the coir in water for a while and break it apart. When soaking the coconut coir, using hot water will speed up hydration.
- These recipes are really flexible. If you would prefer to replace your compost with another organic material, that’s no problem. For example, you could instead use seaweed, bat guano, fish meal, blood meal, soybean or bone meal, or soft rock phosphate.
- If vermiculite is not available, coarse sand can be used instead.
- For cacti and succulents, instead of coarse sand, turface or poultry grit can be used.
- A protective particulate mask is recommended if using a lot of perlite or any organic materials.
- A basic soil pH tester can be purchased to ensure your soil maintains a healthy pH balance. A good potting soil should be around pH 6.5-7 for most plants.
- As compost breaks down over time, the volume of soil in your pots will decrease. In time, you will need to add additional potting soil to your pots.
- Excess soil should be stored in air-tight containers to avoid any insects getting into it.