Compost in the Summer
When gardeners look at their compost pile at this time of year, they assume the sun's heat is doing the work for them. After all, a compost pile needs to heat up and “cook” to break down its ingredients fully, and what better way to do that than utilizing the heat of summer? The heat of summer does speed up the composting process, but it also poses some unique challenges that should be kept in mind for any backyard composting operation. So, what should gardeners look for at this time of year as they maintain their piles?
How Summer Heat Impacts Your Compost Pile
Compost piles are much more likely to dry out at this time of year, making it vital to maintain sufficient moisture for sustaining microorganisms. Microorganisms, including fungi and bacteria, are the key ingredient to successful composting, as they are the ones that do the physical breaking down of organic material. Just like all other life, they too need water to thrive.
Why Moisture Management is Crucial in Hot Weather
It is vital that in the summer heat, a compost pile is not allowed to dry out, but rather be kept damp like a sponge. Gardeners should also watch for too much water, as anaerobic conditions can be just as detrimental to microorganisms, resulting in a “rotten egg” smell from the compost.
Understanding the Microorganisms Behind Decomposition
The microorganisms that drive composting thrive in different heat levels, and the ultimate temperatures dictate which microorganisms do the decomposition “heavy lifting.” This said, in tandem with added water and organic material, these components drive the feeding of microorganisms as they work to break organic matter down into humus. With the addition of ample heat, the process happens quickly. Ironically, a cooling pile indicates a pile that needs to be turned, as the organic material available has been consumed.
When and How to Turn Your Compost Pile in Summer
Pile turning at this time of year should be consistent, yet tackled wisely, as every turning introduces more air to the pile, drying it out via evaporation. A delicate balance must be maintained between keeping a moist and living pile and a well-fed pile. At times, this can mean watering and turning frequently, with ample labor involved, or it can mean that gardeners need to get creative with their pile. Sometimes, when labor is limited and the desire to work in summer heat wanes, the best solution may be to find an alternative.
Smart Strategies for Low-Maintenance Composting
Shading a compost pile with a tarp or shade cloth can slow the composting process in the heat of the summer. Thus, if compost is not immediately needed, it may be best for a gardener to mitigate the extra heat altogether. However, remember that fall soil remediation is just around the corner, so having some extra compost on hand might prove helpful.
Final Takeaway: Keep Your Microbes Happy
With either approach, remember that successful composting is about keeping the microorganisms that drive it happy and well cared for. Done effectively, you’ll have ample compost for your garden in no time.
by Anthony Reardon, Horticulture Small Farms Agent, 2025