Get spring gardens off the ground with autumn soil care

Fall leaves

If you’re like me, the momentum of a busy summer builds to takes over my best laid plans for organization and order sometime in mid-August. When autumn arrives, I feel relief that the rush of planting, harvesting, watering, and weeding will soon wind down. But I have long-since learned that before I let myself fall into a winter sleep, there’s a few crucial things to do in the garden that will make life a million times easier in the spring, both for me and the living creatures that make my garden grow.

Picture this: all the inhabitants of a city the size and density of Tokyo, after napping for four long months, awaken at the same time. Some slowly yawn and stretch. Some burst into activity. All are hungry, but there is no food anywhere. Meanwhile, temperatures fluctuate wildly, and homes are periodically flooded by typhoon rains. These are the conditions soil organisms encounter with spring in many gardens. Amazingly, despite the stress of a violent spring, creatures in this soil survive those rough first weeks until food arrives and conditions stabilize.

Now picture that when the critters in your soil wake up, they are greeted with a feast that helps them warm their bodies and get busy rebuilding their homes. Because there’s plenty of organic matter in the soil, the harsh rains and floods drain faster and have less dramatic effect. Because soil organic matter is abundant and has stabilized over the winter, there is plenty of material for shelter. Nourished in this way, the living soil starts thriving much earlier in the season, jump-starting the living garden system to release nutrients, improve soil structure, drain water, and support healthy living plants.

Gardens grow in the spring, but are fed in the fall.

The difference between these two scenarios is autumn soil care. Keeping in mind the basic principles of nourishing a living soil, we want to make sure that we provide conditions for the right food, water, shelter, and air the following spring. A few hours of work in the autumn can make all the difference in building soils better and faster for years to come.

Forget about “tidying up” – let the mess rest

First and foremost, it’s time for us to change how we think about gardening. Conventional wisdom suggests that we should “tidy up” our garden for the winter by removing garden residues to the compost pile and picking clean the exposed garden soil. When I give my garden this treatment, I take away the food that nourishes the living soil. To keep your soil happy, shift your paradigm to appreciate the wealth of resources contained in garden “mess”.

Later Summer Watermelon

Remember the old adage, “Give more than you take.” The same applies to our gardens. If we take away the end of the season “mess” that our gardens worked hard to produce, we have to return the nutrients and organic material to the soil in some other form. It’s much easier, in my opinion, to leave the garden amendments right where they were grown, creating a self-feeding and natural soil system.

Before you pack it in for the winter, follow these simple steps to bed your garden down for the winter by providing the conditions spring soils need to thrive. Remember that the spring soil food web is fed by the fall garden. Resist the urge to ignore the fall garden because soil building starts NOW!

Step 1: Return the residues

Return fall residues
Return fall residues, even woody ones like these okra stems, to rot over the winter.

The residues left after the garden has finished feed the soil with essential organic matter. The key to using what’s left of the end of season is ensuring good soil to residue contact. You can do this simply by chopping the residues lightly into the soil. To do this, I like to use a sharp, heavy square-bladed spade. Start chopping the material with the blade of the spade, breaking residues into smaller pieces that decompose more quickly. The chopping action also mixes the material into the soil to activate a feeding frenzy.

As an alternative, use a spade, weedwhacker, or sharp hoe to cut the plant residues off at the ground surface. Simply layer these materials onto the soil surface as a mulch. If using this method, I’ll lightly stamp or cut up the material so that it has good contact with the surface of the soil.

Do not use diseased or heavily pest-infected plants. Remove these to the trash, burn pile, or green waste bin. As an exception to good soil building practices, turn over and expose soils when dealing with bad infestations of pests that overwinter in soils.

Garden weeds provide a similar source of organic food. Our gardens also worked hard to grow those pesky weeds. If we take them away at the end of the season, we steal more soil food. Instead, treat them like other garden residues, either by lightly incorporating them or cutting and layering as mulch. Some low-growing and easily incorporated ground cover weeds, like chickweed or purslane, can be left in place, functioning as a natural cover crop. Just be sure to kill weeds before they go to seed.

Do not use weeds that have seed-heads or noxious weeds that reproduce from the tiniest amount of root material. Throw these in the trash, burn pile, or green waste bin.

Leave roots to rot

Roots contribute an enormous amount of organic matter to the soil. Narrow zones around roots, known as the rhizosphere, are hot spots of microbial activity. If there’s not a good reason to pull up roots in the autumn, then leave them in place for over-winter food and shelter for organisms. Believe it or not, most root matter will decompose over the winter.

Step 2: Add Fertilizers and Lime

Lime materials and slow-release organic fertilizers need time to activate. If added in the autumn, they are available when soils wake up in the spring.  Lime additions are not needed every year, but if using, add on top residues in step 1 or amendments in step 3 and incorporate everything together. If I’m addressing a substantial phosphorous or potassium deficiency, then I’ll also add slow-releasing rock powders (greensand, collodial phosphate, or rock phosphate) at this time, as well as slow-release, micronutrient-rich kelp meal. I’ll wait to add other fertilizers, particularly nitrogen, in the early spring too keep nutrients from leaching with winter rains.

Although I almost always want to wait to add nitrogen in the early spring, I occasionally make an exception. If my garden residues are extremely brown and woody, or if I’ve actually added wood chips or sawdust as an organic amendment, I sprinkle a nitrogen fertilizer, such bloodmeal (~1/4-1/2 lb per 100 ft2) or fresh manure before covering it up for the winter.  This helps the very low quality material decompose, while the added nitrogen is actually immobilized in the decomposing woody material to be slowly released in the spring.

Step 3: Add everything else

At this point, anything else that you add to the soil in the autumn has the benefit of breaking down over the winter and prepping soils for spring. This is a great time to add compost, composted manure, or raw compost materials, like alfalfa hay, kitchen scraps, or green hedge trimmings. Autumn leaves are the consummate soil conditioner, so if you have them, add them now. Even very low quality wood chips or sawdust can be incorporated, if covered with nitrogen fertilizer (see above). Lightly incorporate these amendments into the top few inches or soil or use them as a covering layered mulch.

 

Remember that too much of a good thing is not always good. If you want to plant your beds in the spring and summer, then don’t exceed your soil’s ability to eat up the added amendments. Unless you are building a longer-to-decompose sheet mulch, generally don’t apply more than 1-2 inches of compost, 1/2 to 1 inches of manure, or 2-4 inches of leaves or other raw material. Also, keep in mind that added amendments will keep most soils (except for very sandy ones) cooler and wetter in the spring. So for early spring crops, amend conservatively in the fall for a warmer start to the season.

I prefer to add high-nitrogen fresh manures (as opposed to composted manures) a few weeks before planting in the spring. The concentrated nitrogen that immediately releases and leaches from the fresh manure can then match my garden’s nitrogen needs. This means it is taken up in the living mass of the garden itself, instead of being lost from the soil. However, there is a food safety concern with using fresh manure due to pathogens. Regulations for commercial growers require that fresh manures are added 2-4 months before harvest, which usually equates to amending in the autumn. If using fresh manures in the spring, know your manure source and be careful to use good practices to avoid contaminating produce, tools, or hands.

Step 4: Cover it up

Using leaf mold compost
Mulch over fall residues with other organic materials, like grass clipping and partially decomposed leaves. Add mineral organic fertilizers and lime before covering up for winter.

You’ve left the mess and fed your soil for the spring. The final step it to put your garden to bed by covering it. Leaves, straw, compost, living plants, or any other amendment can bed the soil down for winter. Use the amendments or residues added in steps 1 and 3 themselves as a cover, or add additional mulch over incorporated residues and amendments. Don’t forget that living plants are also a way of mulching the soil, whether using cover crops (see extra credit), non-noxious weeds, or overwintering vegetables.

Even if I haven’t had the time to amend or fertilize, I will always cover up my soil. First and foremost, a bare soil is a lost opportunity to amend the soil with organic matter. Placed on soil surface, organic mulch feeds the soil food web through the action of worms and other burrowing organisms. Even more importantly, a bare soil exposes the topsoil to damage from rain and erosion, while leaving the soil food web without shelter for a significant portion of the year.

Extra Credit:  Cover Cropping – It’s easier than you think

The best way to feed and cover the soil is actually with living plants. Remember that plants harvest the energy of the sun to create organic matter. When we amend the soil with compost, manure, or residues, we recycle organic material. When we grow cover crops, on the other hand, the garden actually grows its own organic matter. Using cover crops over the winter, also functions as a protective cover (step 4), a fertilizer (in the case of legumes), and a catch crop that takes up leftover soil nutrients to hold onto them over the winter and protect them in the spring.

Though cover crops may seem daunting, they are actually easier then many people think. My suggestion is to throw out seeds and see what happens. In frost-free southern climates, winter cover crops can be thrown out at any time in the autumn. In northern regions, however, cover crops need to establish before winter. Depending on the species, this means planting 30-60 days before the first frost. To catch this window, get creative. Cover crops can be seeded into a bed prepared and amended for them. You can also embrace the mess and plant directly into residues or still-growing fall gardens to get the cover established. If you are over-seeding in this way, use a higher than normal seeding rate to improve the chances of success.

What’s next?

In the autumn, soils are soft and supple from a season of growing, and without torrential spring rains, are usually dry enough to work. Enjoy the brilliant fall weather by taking the time to put your garden to sleep, getting the satisfactions of watching the winter transformation. You and your garden can get started earlier in the spring with minimal preparation.

Don’t Fall Down on the Job – Spring Starts with Autumn Soil Care
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