The non-chemical method for controlling soilborne pests 

Hinterland Homesteading with Racheal Pascoe

After a bumper year in the veggie patch, it is time to think about wrapping a lot of it up for summer. I have just last week picked my last 5 cauliflowers, all the broad beans, and dug up some stray potatoes I had left in the ground. While I still have herbs growing, asparagus going like mad and kale in abundance, it is time to think about minimising the work in the garden over the summer months. 

The heat gets too much for most things here in South East Queensland. We need to work smarter about tackling that perpetual job of weeding! 

Have you ever heard of soil solarisation? It is a non-chemical method for controlling soilborne pests using high temperatures produced by capturing radiant energy from the sun. Sounds fancy doesn’t it? All it really involves is covering your veggie beds with black plastic over the hot months to keep the heat in. This method involves heating the soil for 4-6 weeks. 

During this time the top 12 – 18 inches of soil is heated to temperatures so hot, it will kill off a wide range of soilborne pests, including weeds, plant pathogens and nematodes. 

The soil can get up to 60 deg celsius. This method is terrific as it doesn’t involve chemicals, is relatively cheap to put in place and easy to establish.

Here at home, we are constantly fighting the weeds Paterson’s Curse and Cobblers Pegs as well as lots of others. Soil solarisation of your garden beds for the summer will ensure that you have weed free veggie garden beds for the start of the planting season. How wonderful. It is disheartening to have to do a big weed pull before even starting the fun stuff of planning and planting. Change it up this year with how you do things!

If you don’t have enough plastic to cover all your beds, maybe you could select a couple to do this summer and then rotate it around next year? You will be in turn starting to minimise your weeds.

Give your garden bed a good water before laying the black plastic over the top. Keeping the soil moist will improve the heated conditions and accelerate the killing of weed seeds etc. We use bricks to hold down our black plastic. You could use lengths of timber or even tie rope around a raised bed.

Where to get your plastic from? You can head to the hardware store and buy a roll of builders’ black plastic. If you are going to set up a kit for using each summer, this would be a good investment. Gardeners though do like to recycle and reuse! 

Keep your eye out for any packaging which comes in the mail with things you buy. Plastic sheets you could cut up the middle and make bigger. Sheets of cardboard can also be layered to smother the weeds. 

Old tarps can also be used. While plastic is the best as it is non porous and keeps the heat in incredibly well, other things can be used successfully as well.

When we are in full planting mode next March, you will be able to pull back the plastic from your beds, revealing a weed free bed, ready to plant out! Happy gardening everyone!