What to add? Compost, raw organic matter, and organic nutrients. Autumn is a good time to improve your soil by adding raw organic matter, such as shredded leaves.
Compost, a crumbly soil-like material, is alive with worms and beneficial fungi and bacteria. It enriches soils, provides nutrients and increases the soil's ability to hold moisture. Several inches of compost can be piled on top of vegetable beds in autumn. Worms and other organisms will slowly work it into the soil.
Fall is the best time to add compost to perennial gardens. Apply a top dressing of about an inch or 2 of compost. You can work it into the top few inches of soil or just leave it on top as mulch. Applying compost in autumn will give perennials a healthy boost for the coming spring.
Remove Summer Edibles, Diseased Plants and Weeds
Strip plants of any remaining fruits and seeds and remove them from garden beds. You can add the plants to a compost pile, if you have one, or toss them in the green wastebin. (Fall is a great time to start composting.)
Layer fallen, shredded tree leaves, compost and fertilizer in the garden bed and turn under the soil. You could also dig trenches in the garden, pile in the leaves and compost and cover with soil. These organic soil amendments will decompose over winter and leave the soil more fertile when spring rolls around.
The fall is the best time to add compost or manure to your garden soil. There are many forms of nitrogen that can exist in compost or manure. Not all forms of nitrogen are forms that plants can use. Some forms of nitrogen need to be broken down by bacteria or other plants into forms that are usable.
Whether you're new to gardening, or a seasoned pro, building better soil is the single most important thing you can do to improve your gardening success. And fall is the best time to do it! To learn more, read Building Healthy Soil.
When winterizing your garden, instead of aerating and raking the soil where your roots veggies are, just put down a nice protective layer of mulch or leaf mold. This will help keep moisture and nutrients locked in the soil.
On other edible crops, fresh manure applications should be made at least three months prior to harvest. With just a four month or so growing season, this means you should only apply fresh manure in the fall; not in the spring or during the growing season to any area that is or will be planted with food crops.
If you have a light, rich garden soil, and you're using compost to maintain rather than to remediate it, then there's no need to dig it up. Just spread the compost on top. Worms, rain and microbial action will mix it into the soil beneath it.
Ideally, this thin layer of compost should be mixed into the top few inches of topsoil but you can seed directly over the layer of compost too. For established lawns, spread a half-inch layer of finely sifted compost over your grass to provide nutrients and reduce your need for fertilizer.
Winter crops for cold frames or hoop gardens tend to consist of cold-tolerant greens, herbs, and root crops. Nitrogen is the best fertilizer for growing leafy crops, while phosphorus and potassium support strong root growth.
Add a Layer of Finished Compost and Mulch: Push aside mulch, pull any weeds, and add a 1-2-inch layer of finished compost. Lightly cover the beds with the old mulch to help suppress weeds and protect the soil without insulating the beds. Many diseases and pests are killed when the soil freezes in winter.
When you're preparing your garden beds for a new season, don't rip your plants out of the ground, roots and all. If you do, you'll be robbing your soil microbes of a good meal and degrading your long-term soil fertility.
Fertilizing in the fall helps plants be hardier when the temperatures drop. We also recommend applying fertilizer in the late fall, toward the end of October or early November. This application will catalyze one last frenzy of root growth and really give your plants some staying power through the cold months.
Plant a cover crop or add mulch
Most soil should not be left uncovered. Keeping the soil covered is key to soil health.
No, you do not have to change the soil in raised garden beds. You should, however, amend the soil with compost and other nutrients before the beginning of each new season. And also when you have identified any plants that need more nutrients.
You can apply topsoil anytime, but most gardeners like to add it in spring before planting. In the fall, it may also be added as a top dressing that will allow nutrients to break down into the soil. You may add topsoil into plantings by adding to the holes where shrubs are planted.
Preparing for a Fall Vegetable Garden
Although many vegetables grow and mature well into the fall, most need to be started before the nights turn cold. In climates with early frost dates, your fall garden will need to be started in mid-summer from late July through August.
Compost can be added to existing soil. I prefer to layer it on top (using a no-dig method) so that I don't disturb the soil.