Our highbush blueberries produce beautiful crops year after year, and I’m convinced that the only secret is to mulch. To grow blueberries successfully, attention must be paid to the shallow surface roots, which need to stay moist rather than dry. Penn State and Cornell agree that any mulch is a good blueberry mulch, but what’s the best?
I suppose the correct answer depends on your site, soil, and available mulching materials. But after trying three blueberry mulches -- wheat straw over roll-out paper mulch (2007), bark mulch over newspapers (2008) and hay over newspapers (2009), we still weren’t getting the weed suppression we wanted.
As luck would have it, a sawmill opened up down the road last year, and they have mountains of sawdust. For just over thirty bucks, a dump truck brought us a little mountain of our own. What wonderful stuff! It’s so light that we use a snow shovel to move it.
Sawdust mulch has a 60-year history of success with blueberries, and many experts think it is in a class by itself. In Blueberry mulch - revisited, Virginia extension specialist Charlie O’Dell describes bringing an old, neglected blueberry planting back into production with sawdust mulch, piled 6 to 10 inches deep. But what really convinced me was Sawdust is My Slave by Rupert Stephens (1879-1976). In this cool old essay, Stephens tracks his use of sawdust mulch in his berry plantings in the 1940’s.
To offset any temporary nitrogen loss at the soil-sawdust interface, I put down a generous helping of turkey manure-based organic fertilizer before piling on the sawdust. The blueberries have never had it so good.