How to Improve Your Raised Garden Bed's Soil in Fall

By Joe Lamp’l - Gardening Expert and Host of Growing a Greener World®
October 21, 2023

As a gardener, fall is always an exciting time for me because I know it’s the perfect opportunity to enrich the soil in my garden beds. With many seasons and successful gardens behind me, I know that the work I do each fall to prepare my beds has everything to do with the success I have in subsequent years. I also believe it’s one of the main differences between the productivity of my garden vs. other gardens I see in my travels across the country each year.

Investing time and resources in building your soil is like putting money in the bank. The more you pay attention to what goes in your soil, and when, the better the returns coming out. This leads back to why I’m such a fan of fall for doing much of this work. Although there’s never a bad time to amend the soil, in fall, during that transition time between warm and cool season plantings, my beds are temporarily vacant, if even for a just a day. Yet it’s that day, that may be the most important of the entire year.

Think of it this way; all through the year, your plants are growing and drawing energy from the sun, and nutrients from the soil. Yet in a finite space, the nutrients within it will likely be exhausted by the end of the season. So it’s essential that you replace those depleted reserves. Otherwise the soil becomes unproductive, and plant vigor, disease resistance and productivity suffer as well.

My amendments of choice are organic, well balanced, and free to make or inexpensive to buy. There are many choices that fall under this category but my favorites include the following:

1) Add Compost to Your Garden Beds

My number one go to choice always. Compost has the important nutrients plants need, great soil building properties, microorganisms to improve and mediate undesirable soil, and you make it for free.

hands holding compost

2) Shredded Leaves and Wood Chips Help Your Soil

Free, abundant and amazing for how they improve soil. Much of the nutrients taken up by trees can be found in the leaves, which can end up in your garden beds. Collect as many leaves as you can, grind them up first with a mower, and let them rot over winter in a big pile or compost bin. Next summer, they should be ready for your garden to mix into the soil are added as a top dressing of mulch.

Wood chips: The wood chips left behind from those big grinding machines that turn whole trees and limbs into this is another priceless amendment for your garden. Seek out tree service companies and arborists in your area about getting a load or two. I have a couple loads deposited every year. In that time, the chips break down to soil and much smaller pieces of wood, which I then add straight to my garden beds.

3) Worm Castings Improve Soil Health

AKA worm manure, they’re rich in nutrients and disease-fighting microorganisms. You can find worm castings in better independent garden centers by the bag or you can order online in bulk. They aren’t cheap but they’re well worth it. Fortunately a little goes a long way. Only about two percent by volume worked into just the top few inches of your soil will do wonders.

worm castings on the lawn

Worm Castings naturally in the lawn

4) Add Nitrogen to Garden Beds

Although everything I add to my soil as an amendment contains some nitrogen, I like to supplement what’s there. Nitrogen is a vital primary nutrient for plants and it’s essential to building great soil. The sources for supplemental organic nitrogen are many, including animal byproducts such as blood meal, crab meal, and fish emulsion, to plant ingredients such as alfalfa, cottonseed, and soybean meal. Even granulated slow-release organic-nitrogen fertilizer such as Milorganite is an option I use often.

As long as I’ve been gardening, I’m still amazed at how giving some attention to building great soil with the appropriate amendments can do to improve even the worst soil. The rapid transformation is nothing short of amazing. The simple process, utilizing readily available ingredients, means there’s no reason great soil can’t be in your gardening future too. And fall is a great time to get started!