How to sterilise soil for new seeds
That pile of soil that you used to grow winters crop of plants is about ready for a revamp before the warmer weather really sets in. Soil, especially soil which has been used for a couple of growing seasons can harbor pests, diseases and the seeds of weeds, even if you’ve been rigorous about plucking them out. To ensure a healthy, happy garden bed it’s a good idea to sterilise your soil before a new season of planting. Here are three ways to do it:
1. Sterilising with steam
Steaming is the optimum way to sterilise potting soil, as the steam will kill anything living in the soil. Steaming can be carried out using a pressure cooker or sterilising container.
- Using a pressure cooker: Pour three to four cups of water into your cooker and place shallow pans of soil over the top of the rack. Cover with foil and close the lid. It’s important to leave the steam valve open enough to allow steam to escape. Heat for 15 to 30 minutes.
- To sterilise without a pressure cooker: Pour 10cm of water into a sterilising container. Place soil filled, foiled covered pans on a rack over the water. Close the lid and bring to a boil, allowing a small gap for steam to escape. Continue boiling for 30 minutes then allow to cool.
2. Sterilising using the oven
To sterilise with your oven, put some soil in an oven safe container and cover with foil. Using a heat safe thermometer, bake at 80 to 90°C for 30 minutes or until soil reaches around 82°C. Remove from oven and allow to cool.
3. Sterilising using a microwave
To sterilise using the microwave, fill a clean microwave safe container with moist soil and cover with a lid. Add a few ventilation holes. Heat the soil for 90 seconds for batch on full power. Allow to cool and leave in container till ready to use.
Related links:
How to make a self-watering planter
Are those seeds viable for planting?
What you need to know to choose the best plants at the nursery