One of the most important steps in successfully overwintering a raised garden bed is to build up the soil's organic matter before the cold hits. After years of working in gardens and studying horticulture in depth, I've learned that a well fed soil can carry your garden through winter and come out even stronger in spring. Around late autumn, I remove any remaining plant matter, check for pests, and then top the bed with a thick layer of compost followed by mulch. This not only insulates the soil and protects beneficial microbes but also slowly feeds it throughout the colder months. I often recommend using straw or leaf mulch about 5 to 10 cm thick because it breaks down nicely and is easy to work with in the new season. One standout example was a client's vegetable bed in the Dandenong Ranges where frosts are a regular issue. After applying these techniques, the soil structure and fertility actually improved over winter, and we had an incredible early start to the growing season with root veg that just took off. My background as a certified horticulturist helped me identify the right compost blend to use and the best mulch for that specific microclimate. This level of detail comes from years of practical experience and education, and it's something I bring to every garden I work on.
I tend to recommend cleaning up your garden beds prior to overwintering them. So, pulling out any dead plants, pulling weeds, and picking up any fallen leaves or other debris. Planting cover crops is a pretty common practice prior to winter as well, as things like barley, oats, or rye can help protect your soil from winter erosion and give it a nutrient boost for spring as well. From there it's pretty simple, I'll lay down some mulch or compost to protect the soil and help keep roots warm over the winter.