The Great Compost Application Debate: Autumn vs. Spring Application
When Should Compost Be Added To Soil? Are Autumn or Spring Applications of Compost Best? What Do Experts, Charles Dowding & Huw Richards Say?
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Compost is a valuable organic amendment that can significantly improve soil health and enhance plant growth. For healthy soils and plants I consider it essential, but accept it could be a top dressing of well rotted com-oat or the addition of well rotted farmyard manure. However, whichever you use, there’s been a longstanding debate among gardeners regarding the best time for applying compost: autumn or spring. Read more below interested in The Great Compost Application Debate: Autumn vs. Spring Application
Renowned gardening experts Charles Dowding and Huw Richards offer differing perspectives on this matter. Is one right and the other wrong? Or is it more subtle than that? Does it even matter?
Let’s look at their respective rationales and decide.
Charles Dowding’s Autumn Application Of Compost
Charles Dowding, the leading proponent of no-dig gardening, advocates for applying compost in late autumn or early winter. His reasoning as I understand it is as follows:
Winter Weather: The cold winter weather helps to break down the compost more effectively, allowing it to integrate into the soil more readily.
Nutrient Release: Over the winter months, the compost gradually releases nutrients that are readily available to plants when they begin to grow in the spring.
Weed Suppression: Applying compost in autumn can help to suppress weed growth during the following spring and summer.
Huw Richards’ Spring Application Ideas
Huw Richards, an organic gardening expert I greatly respect, suggests that spring might be a more suitable time for applying compost. His arguments as I understand them include:
Soil Structure: Applying compost in spring can help to improve soil structure and drainage, making it easier for plants to establish themselves.
Nutrient Timing: The nutrients released from compost in spring coincide with the period when plants are actively growing and require the most nutrients.
Avoidance of Compaction: Applying compost in spring can help to prevent soil compaction, which can hinder root growth.
Weighing the Pros and Cons
Both approaches have their merits, and the best time to apply compost may depend on individual circumstances and gardening goals. Here are my thoughts on the advantages and disadvantages of each method:
Autumn Application
Pros: Effective for breaking down compost, releases nutrients as the soil warms up in spring, suppresses weeds by covering the soil surface.
Compost can be applied around existing plants eg Brussels and other taller crops.
Cons: May not be suitable for heavy clay soils, as the compost can become waterlogged. But remember the soil is also going to be waterlogged anyway.
Spring Application
Pros: Improves soil structure, releases nutrients when plants need them most, avoids compaction.
Cons: May be less effective for breaking down compost, potentially leading to slower nutrient release.
A Balanced Approach
Ultimately, the ideal time to apply compost may lie somewhere between these two. Consider the following factors when making your decision:
Soil Type: If you have heavy clay soil, applying compost in the spring might be preferable to avoid compaction if applying the compost in inclement weather means walking on the soil .. but we all know not to walk on side soil anyway and can delay the application until drier. And if we are using a bed system of some sort, Ie we have permanent paths, there should be no need to actually stand ion the soil!
Climate: In colder climates, applying compost in autumn may be more beneficial to allow for winter breakdown.
Gardening Goals: If your primary goal is to suppress weeds, applying compost in autumn might be a good strategy. However, if you’re more concerned with improving soil structure and providing nutrients for plants, spring application could be more effective.
A Wider Soil Perspective
So far in this article I have discussed adding compost in spring to autumn as if it can be considered in isolation. But life is more complex than that and we need to consider other factors.
The addition of some form of organic matter is essential in my view as it feeds the soil and that feeds the plants. But we also need to consider things like plant root exudates. The role of root exudates is now well established in plant and horticulture scenic. In my view compost needs to be added at a time when it allows us to maintain some form of plant cover throughout the year. So the ideal time might well be between crops .. whatever time of year that might be. For example we may have grown broad beans over winter and benefited from their nitrogen fixing ability. As we remove the crop reside, taking care to leave the roots in situ, we can add compost before planting the next crop. Ideally the next crop will nee painted within hours of moving the top growth of the beans.
But there is an alternative to this when growing beans. If we grow the beans in rows we can throw some compost up between the plants whilst they are still growing. This can be anytime after they are big enough to cope with the minimal disturbance. This provides a lot of flexibility to our time scales .. and extends the compost addition window right through the winter.
There is another consideration. Both Charles and Huw talk about having nutrients available for spring growth. But wee know that compost needs breaking down by the soil microbes before it is available too plants and that this takes time. So adding the compost earlier rather than later makes sense to me.
Compost break down is of course temperature dependant. It happens faster as the soil warms up. This is because microbes tend to multiply faster in warmer conditions. But good dark compost strewn on the soil will warm faster than ordinary soil. So to warm the soil it makes sense to add this dark gold in time for it to warm up!
We also need to consider leaching of any nutrients released from the compost. The fear that all the “goodness” will get washed out by winter rains. The reality is more nuanced than that. In bare soil this can happen. But where we have crops, green manures or other plants growing they can scavenge nutrients as they are released.
For example I have written elsewhere about how fodder radish (or mooli) will nitrogen scavenge all winter and then, when they die, will release the nitrogen for spring grown crops.
My Compost Application Debate Conclusion
While there is no definitive answer to the question of whether to apply compost in autumn or spring, both methods can be beneficial. By carefully considering your specific gardening needs and conditions, you can determine the approach that best suits your goals and helps you create a thriving garden.
