The benefits of Rice hull mulch

A couple of years ago we started experimenting with the use of parboiled rice hulls as mulch in our container plants. It has been a learning process, and although we still haven’t perfected the application method, we now use it on all of our finished perennials.

The main reason that we started using rice hull mulch was to find a way to suppress liverwort. As you know, liverwort is the bane of many nurseries’ existence. Throughout the years, we have spent countless weeks in spring cleaning liverwort out of pots. And that wasn’t the end of the story; we would also have to replace the inch or more of soil displaced by all the liverwort in each pot.

The first year we tried the rice hulls, we didn’t apply it thick enough and it wasn’t effective. But after realizing that it needs to be at least ½ to 1” thick to suppress weed growth, we were impressed by how well it worked. While we still have to spend time cleaning up weeds, they aren’t nearly as bad, and our liverwort problem is almost nonexistent.

Another added benefit to using the rice hull mulch is that it helps protect newly planted liners against desiccation. This is especially helpful on those hot, windy days in summer when unrooted liners can dry out so quickly. We were worried at first that the mulch would seal in too much moisture on varieties that are already sensitive to overwatering (like Heuchera). However, we use it on every perennial we grow and, so far, haven’t seen noticeable adverse effects with any specific varieties.