I still hear the old adage “hoeing conserves water” being repeated by home gardeners. This is one of those old garden myths it’s hard to shake. The theory is that hoeing breaks up capillary pores through which water rises to the surface, thus preventing evaporation and saving water.
Capillary Action
There is even a name for this top layer of cultivated soil: dust mulch. However, the dust mulching technique was thoroughly tested back in the 1930s and was found to be ineffective. It turns out soil actually self-regulates water lost to evaporation: as it dries out on the surface, capillary action is quickly cut off, even without hoeing. Where hoeing does reduce water loss is by removing weeds that also use water, thus removing the competition for water by other plants… but hoeing also causes serious damage to the plants it is supposed to protect because it damages their roots, stopping them from adequately absorbing water. Plus hoeing destroys beneficial microbes living in the soil. So hoeing removes weeds, check, but doesn’t save water, check, damages the roots of desirable plants, check, and kills the good guys, check. Not such a positive result!
Mulch, Don’t Hoe!
Rather than hoeing, why not just use an organic mulch? Applied early in the season after the area has been thoroughly weeded, a 3 to 4 inch mulch of chopped leaves (my favorite, because is totally free!) prevents weeds from germinating while efficiently reducing soil capillarity, thereby reducing evaporation by 75% and more, depending on the soil type. Plus mulching leaves the soil microbe population (one of the gardener’s greatest friends!) in peace. If water conservation (and good gardening) is your goal, don’t hoe, put in mulch!
This text was first published on this blog on July 3, 2014. It has been revised and the layout updated.
Love this common sense, inexpensive, good-for-the-environment advice. Thank you!