Sour Mulch

Producing healthy, high quality mulch is an organic process that involves decomposition. In fact, that organic breakdown is part of what makes hardwood mulch such a beneficial product for landscapes. However, when improperly maintained, the same elements that work to healthily decompose mulch may turn it sour. Sour mulch contains high levels of ammonia, alcohol, or organic acids that have not dissipated as they usually would during decomposition due to a lack of oxygen exposure and/or an increase in water exposure.

The correct way to produce mulch (and the way we do it here at Almstead) is to turn the piles to distribute oxygen exposure and increase aeration. Mixing the mulch pile also breaks up any pockets that may be holding water. It may seem simple, but this process is essential to the production of good mulch. Unfortunately, turning mulch can actually be quite laborious and time consuming if you are producing large quantities, so not all mulch manufacturers will take the time to do it (especially those new to the business). Rest assured that at Almstead we have very high standards for our mulch and practice turning regularly.

Sour mulch can have negative effects on plants, so it's very important not to apply mulch that you think may be sour. It's termed "sour" because it often smells bad, like rotten eggs or ammonia. Sour mulch also tends to be very warm, so feeling it for temperature is also a good test. Once spread, the toxins in sour mulch dissipate pretty quickly (which makes sense, since the primary problem with sour mulch is a lack of aeration). That also means that any damage to plants (ranging from wilting to more permanent damage) is done very quickly after sour mulch is applied, and removing it will probably not do much to help the situation.

If under any circumstance you believe the mulch you have received from Almstead is sour, please contact us right away. Certainly do not spread mulch you think may be sour, even if you aren't positive. The consistent high quality of our mulch and customer satisfaction are both incredibly important to us, and we will do everything in our power to remediate the situation on the incredibly rare chance that it might occur.