Organic Weed Control
One of the very few frustrating things about moss is that in certain locations, grasses and other weed seeds that blow onto the moss garden can germinate and then need to be pulled out periodically. Preen weed control has been around for many years, but recently the manufacturer re-formulated the product, making use of corn gluten as the seed germination inhibitor. We have been experimenting with this product and find it to be very helpful in minimizing the amount of grasses and weeds that come up in moss. Supposedly the product does not inhibit tree seeds from sprouting, but since we have been using it on our spring house green roof covered with moss, the numbers of seedlings has dramatically declined.
Since it is an all organic product and not chemically based, we feel confident about using it anywhere and also believe it can be applied any time of the year (regularly in spring is a good idea) Here are just a few of the more common weed seeds it keeps from germinating: annual bluegrass, dandelion, clover, crab grass, orchard grass, and plantain. Preen is a seed germination inhibitor and will not impact any pre-existing plants, weeds, or grasses. Applications are recommended every 4-6 weeks during the growing season. If you are seeing weeds growing in your moss it could be time to give Preen a try...