This 'Dust' is good

With the gardening season drawing to a close, you might want to consider "dusting" your garden. Adding sawdust, that is.

Sawdust is a terrific material for enriching the soil with humus, which sawdust eventually becomes. Leaves, straw, and hay and other once-living things can also do this and do it well, but sawdust has the advantages of being longlasting and weed-free, and the small particles mix intimately with the soil. 

Sawdust is also cheap, often free for the hauling, from sawmills, lumberyards, or from your or a friend's workshop. All kinds of sawdust are suitable except, of course, sawdust from wood that has been chemically treated.

Once you get a load of sawdust, you can either spread it on top of the soil or dig it in. Generally, it's more effective spread on the soil, where it modulates soil temperatures in winter and summer, smothers weeds, seals in moisture and is gradually transformed into humus.

But if your soil is a heavy clay that's rock-hard when dry and sticky goop when wet, digging a 6-inch deep layer into the top foot of soil can really help loosen it up. Then lay out your garden in permanent planting beds, with paths of stepping stones for walking, and you should never have to do that digging again.

At this point, many knowledgeable gardeners start muttering about sawdust temporarily robbing plants of nitrogen. True, but that's no reason to shun it. Simply add some extra nitrogen along with the sawdust.

As a rough guide, sprinkle four pounds of any fertilizer having about 10 percent nitrogen over every 100 square feet of ground that is going to have that 6-inch depth of sawdust dug into it. Throw on a pound and a half of limstone too, to offset the temporary acidity from the sawdust.

No need for any concern about nitrogen when you use sawdust as a mulch. Laid on top of the soil, sawdust is slowly transformed to humus at the thin interface where the soil and sawdust meet.

One of the best testimonials to the use of sawdust as mulch comes with growing blueberries. Blanket the ground beneath these plants with a 3-inch depth of sawdust late each autumn and you'll be amazed at how the plants thrive in the loose, moist, humus-y ground created. You'll also, incidentally, bury spores of mummy berry disease.

Rhododendrons, azaleas, mountain laurels, and heaths -all kin to blueberries- also are especially fond of sawdust mulch.