I make my own seed raising mix to ensure that my seed trays have every chance of success whilst germinating. As our summers get very hot, moisture seems to be the problem with seedlings. By adding coconut fibre (coir peat) bigger healthier roots grow and require less water, as the product has a higher water holding capacity. The addition of vermiculite also enhances moisture retention. This recipe makes up to 15 litres depending on what coir product you use.
You will need
A bag of potting mix (ensure it has the Australian standard set of ticks)
Vermiculite (can be purchased at the hardware store in the gardening supplies section)
Coir Power Seed Raising Block or Coir Peat Brick (can be purchased at the hardware store in the gardening supplies section)
Container (I use a mini garbage bin)
Shovel or Trowel