Quick Answer
Covering finished compost is generally not necessary but can provide some benefits in certain situations. The key things to consider are preventing the compost from getting too wet from rain, protecting it from getting blown away by wind, keeping pests out, and insulating it to retain heat. A simple cover like a tarp can help address these issues. But in many home composting situations, leaving finished compost uncovered is perfectly fine.
Does Finished Compost Need Protection from Rain?
Excessive moisture can be detrimental to finished compost for a few reasons:
- It can lead to anaerobic conditions, slowing down the final stages of the composting process.
- Very wet compost is heavy to handle and messy to apply.
- Nutrient-rich compost “tea” will leach out from overly wet compost.
Getting some rainfall on finished compost can be beneficial to further break it down. But heavy rains or downpours risk over-saturating the compost.
If you live in a particularly rainy climate, covering finished compost piles is advisable to regulate moisture levels. A simple tarp or plastic sheeting is an easy solution.
Make sure the cover is securely tied or weighted down so it doesn’t blow away in windstorms. Breathable fabric covers are also available that provide protection while still allowing some air circulation.
Does Finished Compost Need Protection from Wind?
Wind can also be detrimental to finished compost for a couple reasons:
- It will dry out the compost, especially in arid climates.
- Strong winds can blow away fine compost particles.
A windbreak made from wooden pallets, burlap sacks, or straw bales can help block drying winds. Placing piles near buildings, fences or trees also helps block wind.
Finishing compost in an enclosed bin helps prevent wind damage. Or simply covering piles with a tarp or blanket secures the compost. Weighing down covers with rocks, boards or stakes helps keep them in place.
Turning and mixing finished windrow piles can also get material on the outer layers back underneath for protection.
Does Finished Compost Need Protection from Pests?
Rodents like mice and rats can be attracted to finished compost seeking food scraps or a warm place to nest. Covers help discourage pests by removing access and hiding the compost.
Certain insects may also take up residence in piles of finished compost. But this is mainly an aesthetic issue rather than causing any real damage.
Repellents and traps can help deal with severe rodent problems. Avoiding meat, oils and fatty food scraps in compost is another preventative measure.
The natural microbial activity in finished compost generates heat, making piles less hospitable for pests. Turning and aerating piles regularly also deters nesting.
So covering is not always needed for pest control. But it provides an added layer of protection, especially during dormant seasons when rodents seek shelter.
Does Finished Compost Need Insulation?
Covers also help insulate finished compost against temperature extremes. This can be beneficial for a few reasons:
- It protects beneficial microorganisms from extreme cold or heat.
- Insulated compost retains moisture better.
- It allows the internal temperature to remain elevated, facilitating continued decomposition.
Maintaining temperatures between 90-140°F (32-60°C) is optimal for the microorganisms responsible for finishing the composting process. This mesophilic temperature range allows them to thrive.
So covers that trap heat energy help maintain these temperatures, especially during cooler months. The microbial activity itself gives off heat as organic matter is consumed. Trapping the rising warmth contributes to the insulation effect.
Turning and mixing piles also brings insulating outer layers back inside. Larger compost piles have greater thermal mass and take longer to lose heat. Insulating finished piles for 1-2 weeks optimizes the final curing.
When is a Cover Necessary?
Here are some specific situations when covering finished compost is more critical:
- Cool, wet climates – Protects from excessive rain and retains heat.
- Hot, arid climates – Protects from drying winds and sun.
- Winters – Insulates against cold and provides protection from heavy snow.
- Summers – Shields from drying sun and heat waves.
- Monsoon seasons – Keeps compost from getting waterlogged during heavy rains.
- Areas with pest problems – Restricts access from rodents and scavengers.
In these situations, the benefits of covering finished compost generally outweigh leaving piles exposed. A simple breathable tarp provides adequate protection in most home composting applications.
When is Covering Less Necessary?
During favorable weather conditions and in pest-free areas, covering finished compost may not be needed. Here are some instances when piles can be safely left uncovered:
- Times of moderate, consistent temperatures and precipitation.
- In arid climates if the compost is already quite dry.
- If turning or remixing piles frequently.
- Small amounts of compost for home use.
- When compost needs to be hosed down or soaked to rewet.
- If requesting natural rainfall to further decompose.
Leaving finished compost piles exposed when the weather cooperates avoids unnecessary work. Just monitor moisture levels and remix regularly to aerate.
Also consider sheltered locations like under eaves or trees to allow covering some of the time. For small compost amounts, storing in covered bins, barrels or boxes may suffice as well.
Covering Materials for Finished Compost
Here are some suitable materials for covering finished compost piles:
- Tarps – Heavy duty ones resist tearing and withstand weather and UV rays. Choose breathable types like canvas.
- Plastic sheeting – Low cost option that blocks rain. Avoid plastic that touches compost.
- Landscaping fabric – Allows airflow while blocking light and moisture.
- Straw – Provides insulation if thick enough. Hold down with netting.
- Leaves or hay – Need to replenish as they decompose but easy to use.
- Wood boards or pallets – Can construct simple A-frames or lean-tos.
- Cardboard – Recycled boxes offer a biodegradable option.
Choose a durable, breathable cover that suits your budget and needs. Overlap cover edges when layering multiple pieces. Weigh or tie down covers securely.
Remove covers periodically to check compost moisture and remix piles as needed. And remove materials once compost is fully cured to avoid contaminating finished compost.
Conclusion
Covering finished compost is certainly not mandatory, but offers benefits in many situations:
- Protects from excessive wind, rain, or snow.
- Prevents compost from drying out or getting waterlogged.
- Insulates piles to retain heat and moisture.
- Deters pests from taking up residence.
- Reduces risk of contamination once compost is cured.
Even a simple tarp can go a long ways in regulating elements and trapping heat. Monitor piles closely and adjust coverings as needed. Remove once compost is fully cured.
Evaluate your specific climate, scale of composting, and pest pressures. In many backyard composting scenarios, uncovered piles work perfectly fine. But take advantage of coverings when the situation calls for it.
Related Questions
How long does finished compost need to cure before using?
Finished compost usually requires 2-4 weeks of curing time before using. This allows the beneficial microbes to further break down any remaining particles and for the pile to stabilize. Covering piles helps insulate them during curing. Test cured compost to ensure it no longer heats up and has a pleasant, earthy odor.
What are the signs that compost is finished?
Finished compost is dark, crumbly, and earthy-smelling. It no longer heats up after turning. Particle size is uniform and no original materials are visible. The pH is neutral and nitrogen levels are stable. Compost should feel moist but not soggy. A ratio of 1:1 to 2:1 brown to green materials is ideal. Finished compost is safe to handle and apply.
Is covering compost required in municipal or commercial facilities?
Covering large-scale composting is often required for odor control, managing runoff, and maintaining properly controlled conditions. Outdoor windrows are covered with fabric blankets that regulate moisture and heat. Piles turned by machinery have the covers mechanically rolled back prior. Industrial in-vessel systems use biofilters for air quality regulation rather than physical covers. Strict environmental regulations apply to municipal compost sites.
References
- United States Environmental Protection Agency. “Science & Engineering – Composting.” Accessed November 7, 2023. https://www.epa.gov/sustainable-management-food/science-engineering-composting.
- University of Illinois Extension. “Composting for the Homeowner – University of Illinois Extension.” Accessed November 7, 2023. https://web.extension.illinois.edu/homecompost/finishing.cfm.
- BioCycle, JG Press, Inc. “Best Practices for Effective Compost Blanket Use.” Accessed November 7, 2023. https://www.biocycle.net/best-practices-for-effective-compost-blanket-use/.
- United States Department of Agriculture. “Chapter 2: Composting Methods | NRCS New Jersey.” Accessed November 7, 2023. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/soils/?cid=nrcs144p2_018762.
- Lowe’s. “Composting Do’s and Don’ts | Lowes.com.” Accessed November 7, 2023. https://www.lowes.com/n/how-to/composting-dos-and-donts.
