Apply Compost in the Fall

Since a laidback gardener has no need to cut back perennials in the fall or rake up dead leaves and drag them out to the street, what should we do at this time of year if we want to garden? Have you thought about putting compost in your vegetable garden this fall?

Wheelbarrow with shovels, next to a compost pile compost pile
Have you thought about putting compost in your garden this fall? Photo: Oregon State University,

“Wouldn’t it be better to do it in the spring,” you ask, “when I transplant my seedlings or plant seeds to properly fertilize them?” Well… actually, no! The main issue is that compost is not really a fertilizer. “WHAT?!?!! You’ve been telling us to put compost in our garden for years, and now you’re telling us it’s useless!”

Compost is an Amendment

Hold your hostas! Just because compost isn’t a fertilizer (it is the equivalent of a 1-1-1 fertilizer) that doesn’t mean it’s useless. It’s more of a soil amendment. Compost is known for its ability to improve soil structure and add beneficial microbes to your soil. It also improves the circulation of air, water and nutrients in the soil which makes these nutrients more accessible to plants.

Fine compost in one hand
Compost is not a fertilizer but a soil amendment. Photo: SuSanA Secretaria, Wikimedia Commons

Compost in the Fall

But why apply compost in the fall? It’s simple: the nutrients contained in the compost are not immediately available to your plants. It can actually take up to 5 years for your compost to decompose completely.

The N-P-K of Compost

You’ll remember that the 3 main nutrients that plants require are nitrogen, phosphorus and potassium. Well, about 10 to 30% of the nitrogen in the compost is available to your plants in the first year. For phosphorus, we’re talking about 35% after one year. Potassium is in a class of its own and seems to be ready to feed your vegetables soon after its application.

Think of it this way: compost feeds your soil, which in turn feeds your plants.

Person taking compost in a wheelbarrow with a shovel to spread it on the ground
Compost can be mixed into soil or simply spread on the surface. Photo: Greta Hoffman,

How to Add Compost?

Typically, compost is added by mixing it into the soil to a depth of 6 inches (15 cm), but… it is just as effective when left on the surface as a mulch or topdressing. Apply it thickly, up to 3-4 inches (7 to 10 cm), if you have enough.

Compost? Anytime!

Is it bad to apply compost in the spring? Absolutely not! But you have to remember that its benefits will be delayed. If you do it in the fall, some of its nutrients will be available in the spring. Personally, in my vegetable garden, I use a slow release all purpose organic fertilizer for immediate needs in addition to compost. No stress! Compost can be applied anytime, even in the fall!

Mathieu manages the and websites. He is also a garden designer for a landscaping company in Montreal, Canada. Although he loves contributing to the blog, he prefers fishing.

10 comments on “Apply Compost in the Fall

  1. This would probably also depend on the weather conditions. For example, warmer climates would make it available faster as it would decompose faster.

  2. hmmm . . . This is a bad topic for us at the moment. I am supposed to cut down the leaves of a colony of gunera, and then bury the colony with compost. However, someone who mixed the compost scooped up too much of the rocky soil below the pile, . . . and repeated the process a few times. The pile is now more rocky and sandy soil than compost. Well, the gunera gets no compost this year.

  3. Hello from Sydney, Australia I have really loved and appreciated this blog and your fathers wit and humour like so many. Mathieu I am also grateful for you maintaining it and figuring out how to make it yours. I live in an apartment so much doesn’t apply-but Hold your Hostas-was great. 🙂 and got me my needed morning smile as I get ready for work.

  4. I have the opportunity to buy the following compost mix from a farm: chicken, goat, steer, horse, sheep. They say it is “unfiltered” so it smells. They say it is “well rotted” for two years. Firstly, how would I ever know that it is well rotted and not going to burn my plants? Secondly, why does it still smell? Thirdly, exactly what do they mean by “unfiltered”. What kind of filtering process would be applied to “filter” it please? Can you explain? I am a new gardener, planning to do square foot gardening in 26″ high raised beds. The square foot gardening method requires 1/3rd of the growing medium to be manure from as many different sources as possible. I want to be ready to go in the spring so I will need to fill my beds before February in my estimation. Can you answer my questions please?

    • marianwhit

      Hi…I can try to help…not sure what filtering (passing it through a screen to filter out large solids and make it uniform and more “soil-like” to work with) and smell have to do with each other, unless the filtering adds air and dissipates some of the smell. I am also sad that humans feel they have to have things that don’t smell like anything…that smell is the smell of nutrients…fecundity, baby!

      If it is well rotted, weeds will try to grow in it, and it will not steam if you turn it on a cool day….you can put your hands in it too, and if it feels warmer than it should for the temperature, it is still “hot”.

      You can filter compost yourself by building a frame with a flat area of hardware cloth that you push the material out the other side…some like a table-like surface (flat) and some like to mount it at an angle…personal choice.

      If the compost is still a little hot, you can get it and turn it a few times between now and the time you use it, and it will probably be fine for use in the spring. If I were getting compost (or any soil additive for my garden), I would go to the site and look at where it is coming from. I learned this the hard way, by getting municipal compost that had not been managed to get hot enough to kill the weed seeds…and introduced 5 new very aggressive weeds to my weeding woes in the 5 gardens where I used it.

      When this happened, I began making my own compost and not seeing “yard waste” as waste. I collect leaves, weeds that don’t spread by roots and not in seed, even twigs, and logs I have allowed to rot in discrete locations, and any kitchen organic material and compost those materials.

  5. It is funny how you answered the very question I didn’t know how to frame but have wondered about for years. What does compost do for the soil besides being an amendment? In the back of my mind I kept thinking it’s not a fertilizer but yet when talking to other gardeners, compost was the go-to for everything! Thank you. I have learned so much from your beloved father in reading these writings and now also you.

  6. Interesting! Can the autumn leaves act as compost ? So can I just mix the leaves in the garden soil?

    • Mathieu Hodgson

      Autumn leaves as best used as mulch. You don’t have mix them in. Just soread them in your flower beds. Its better to shred them, but honestly, i don’t usually bother unless the leaves are thick and tough.

      • marianwhit

        Agreed…I often just rake them into piles and crush them between my hands…that way I am more likely to find and re-hide caterpillar cocoons and chrysalises in the crushed leaves, which a machine can’t do. These animals are essential food sources for songbirds, many of which are declining rapidly…the machines just obliterate all of them.

  7. Very interesting. Good to know.

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