I'll be trying my first raised bed of garlic this fall, and I have a spare bag of cottonseed hull mulch from Stillwater Milling. Does anyone know if this is a good/bad mulch for garlic? Many thanks in advance!
Off the top of my head, I cannot think of a reason why you shouldn't use it. How well it works might vary depending on your location. Some people in windy, exposed locations feel like cottonseed hull mulch blows around too much. Other people who get very heavy rainfall at times have had issues with it washing away easily. However, both of those issue happen with some other forms of mulch too.
In general, cottonseed hulls make a good mulch. However, if you open the bag and it smells bad (a common problem 5 or 10 years ago but not so much today), I wouldn't use it around edible plants.
The quality of cottonseed hulls, in terms of them being chemical-free, has long been an issue, but it depends on the geographic area in which the cotton was grown. For as long as I can remember, and I'd say this dates back to at least the late 1980s, cotton ginning-related by-products from cotton grown in TX or OK were preferred. Why? Because cotton growers here don't have to use chemical defoliants like they do in some warmer climates. Here, the cold arrives early enough to do the job, so gin by-products from this region have been considered 'cleaner' or 'less toxic' than those from some other areas that must rely on chemical defoliants. Also, there has been some moderation in the amounts and types of chemicals used while growing cotton, and organic cotton has become more in demand too, so I feel like cotton gin by-products probably contain very low levels of chemical residue nowadays compared to 10 or 15 years ago.
Regarding the bad odor, that was occurring if cotton byproducts were too wet when bagged. Once the producers began waiting for the byproducts to dry out before they were bagged, a lot of the odor issues went away.
Hope this helps,