Hay Bales and Seed Rot

Seeds pods immediately begin to rot during moist conditions.

Higher temperatures not only make seeds unviable but also seed rot is taking place in the hay bale. Seed rot can occur at a wide range of temperatures (50° to 100°F) but are more common at temperatures above 70°F. Seed rot are favored by excessive moisture.

Hay bales have a tendency to soak up moisture. This moisture in turn rots the seeds contained in the hay bales. For this reason, spoiled hay is far superior to dry hay bales. Dry hay bales can be aged outdoors in order to get the rotting seed effect.

New straw or hay that is left loose on the soil may perhaps sprout seeds. Good aeration will help the seedlings to grow and have a good start in your garden. Aged or spoiled hay is the best way to ensure no germination of seeds.

There is some great conversation about hay on the internet. Here is a site you might be interested in:

http://www.permies.com/t/5057/permaculture/hay-mulch-find-free

My hay bale test did not receive that temperatures that I had hoped for. We had unseasonably moist and mild temperatures. However the seeds on top of the bales have rotted and pose no problems.

My suggestion is that hay bales can be seedy if you immediately untie them and use them in your garden as mulch. You must wait a period of time before opening up a hay bale and using it.  By waiting a few weeks you will  get the heat and seed rot effect. In dry conditions I would wet you hay bales to ensure rotting will take place. Also apply loose soil on them to encourage microbes that help rot the seeds.