Feed the Soil in Fall

Feed your soil this fall so the soil will feed your plants next year.

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Fall is the perfect time to prepare your vegetable, annual and perennial garden beds for spring.  Improving the soil in the fall can make a big difference in the success of your plants next year.  Improving your soil is the most important thing you can do for a successful garden because it will break up compacted or clay soil, improve moisture retention, help prevent disease and pests, and support plant health.

If you give your soil what it needs to feed your plants, you can avoid chemical fertilizer.  Chemical fertilizers do not increase soil fertility.  Chemical fertilizers are depleted quickly and wash out of the soil with rain and irrigation.  Synthetic fertilizers are high in salt, which can build up in your soil and be detrimental to your plants, as well as soil organisms.  Adding organic matter will not only improve your soil directly, but will also feed the insects and microorganisms.  Feeding the good guys will help keep the bad guys out of your soil.  The good guys feed on nematodes and diseases harbored in the soil, so encouraging this activity in the fall will help minimize disease in the spring.

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As your clear the garden of finished crops, put down a layer of about 3-4” of organic matter.  Loosen the soil with a garden fork and then turn the organic matter into the soil.  Thoroughly tilling is not only unnecessary but counterproductive.  Allow rain, worms, microbes and insects to “till” it in, and the soil will settle over the winter.  The encouraged activity in the soil will also keep it aerated and they will add their own organic matter.  But in the meantime air and rain will penetrate the loose soil aiding the breakdown of rough organic matter.  For perennial gardens and shrub borders you can layer a few inches of compost around the plants without contacting the stem or trunk of the plants.  Lightly work it into the soil if the situation allows, but if not, the worms and insects will pull the good stuff down into the soil over time.

Why Organic Amendments and Nutrients?

  • Adding organic matter containing nutrients and minerals to your soil returns the natural matter that has been depleted by your plants.

  • Organic fertilizer is slowly release, feeding the plants as they need it. Chemical fertilizers are available immediately when applied, but depleted rapidly.

  • Organic matter improves the soil’s moisture retention and contains acids that aid roots with the uptake of water and nutrients.

  • Chemical fertilizers contain salt, which will build up in the soil and kill important soil organisms.

  • Chemical fertilizers do not improve soil fertility or soil structure.

  • Chemical fertilizers do not feed insects and microorganisms important to the soil.

  • Finally, do you want your edible plants grown from chemicals? or from natural plant and organic matter? You are what you eat!

So What Exactly is Organic Matter?

Quite simply, it was once living matter that is now dead.  Although different so called categories of organic matter are frequently referenced such as “organic fertilizer”, “organic soil amendments”, “organic matter”, or compost, there is no scientific or biological differentiation.  So don’t let yourself get confused by the semantics.  All organic material contains nutrients that can be used by your plants, and also improve the texture of the soil and beneficial insects and organisms.  Certain organic materials are more specifically “fertilizers” that add nitrogen, potassium and/or phosphorous to your soil.  So what is really important is to understand various organic materials - how do they affect soil texture and/or fertility, and how and when should they be incorporated into the soil.


Finished compost, purchased or homemade, can be worked into the soil anytime, even during the growing season.  It can also be used a s top or side dressing allowing worms, insects and rain to slowly qork in down into the soil.  Finished compost is fully decomposed plant material and should also contain a source of nitrogen, generally aged manure or fresh manure that was added to your compost and allowed to go through the decomposition process with the plant material.  Compost that includes a source of nitrogen improves the soil fertility as well as soil texture.

Raw Organic Matter

Organic material that has not been decomposed, or composted, can be worked into your soil after the growing season.  Raw matter will need nitrogen worked in with it to help decompose the material.  Fresh manure can be used because it will have more than 6 months to age in the soil.  Using fresh manure during the growing season will burn plants with caustic ammonia and also contains harmful bacteria, so typically you would let it age in your compost heap.  If fresh manure is not available to you, use a granular organic fertilizer that is readily available at garden centers.

Shredded leaves are an ideal raw organic matter to use in the fall, they are certainly available in abundance!  If your leaf blower has a shredder, you can accumulate bag after bag of shredded leaves for your gardens.  Or shred leaves with your mulching mower, using the bag attachment so they are easily transported to the garden.

Since raw matter should be shredded or by some means in small pieces, you should not just turn your expired plants over into the soil, they will still be whole next spring.  But you may have a stock of rough, unfinished compost that is perfect for fall tilling.  The decomposition process will easily finish by next spring.  You can also use branches that have gone through a chipper, or sawdust in limited amounts.

Organic Amendments / Nutrients / Fertilizer

An amendment can be literally anything that is added to the soil to affect some sort of change.  But often when we refer to soil amendments what we really mean is Soil Nutrients, or Organic Fertilizer.  These are generally materials that will specifically add nitrogen, phosphorous, potassium, calcium, iron, etc., to the soil.  Or it may be material that will raise or lower the pH of the soil.  Adding basic nitrogen, potassium and phosphorous is common and typically useful for plants.  But if you suspect you need to alter mineral levels or pH, it is best to test your soil first.  Soil test kits are inexpensive, easy to use, and readily available at garden centers.  Organic nutrients are best incorporated into the soil in the fall.  They do not immediately release value to your plants, requiring several weeks at least to interact with the soil.

The most common nutrient used is of course manure, which adds nitrogen to your soil.  Bone meal, blood meal, kelp, bat guano, mushroom compost, etc. are also common nutrients added to garden soil.

See more detailed information about Soil Amendments....

Get started with your fall amendments with any unfinished or rough compost you have, and start shredding those leaves!

Sharon Dwyer