Home & Garden Columns

I’ve been the Mulch Queen, or at least her Majesty’s faithful herald, for years. The sight of our locally predominant clay soil lying naked to the elements upsets me. I know what happens when it gets walked on and rained on—yes, rain does compress soil over time if that soil doesn’t have nearly perfect drainage or spongelike absorption—and dried to dust by the sun.  

Besides, I’m lazy. Or I prefer to mimic natural processes when I can. Choose one; please don’t consult the editors whose deadlines I break habitually, if not merrily.  

When I want to add compost to my garden, I do it by spreading it as mulch. Then I stand back and let the worms do the work, and by gum they do it right. They don’t mess up existing root webs or useful mycorrhizae. (At least, not in my garden they don’t. What imported earthworms have done to the soil networks in some of our forests, that’s a story that can leave me catatonic.) 

And though some folks who plant the margins of apartment blocks in Berkeley seem not to believe it, we don’t have much in the way of dangerously venomous snakes here in the flatlands. The bare dirt between those wilting dwarf rosebushes and mums is just so sad and starved-looking.  

Now comes UC’s Gordon Frankie to mess with my cherished beliefs. Dang. 

We have a surprisingly large number of native bee species right here in Berkeley: at least 74. This doesn’t include the familiar honeybee or one of our leafcutter bees, which are exotics native to Eurasia. Frankie has been doing research and education on the ecosystem roles of assorted bees, especially in pollination. I’ve seen him gently catch bees in flight, hold them for a group’s appreciation, and then release them to resume their business.  

The good news is that we still have that many bee species in the city. The bad news is that, according to Frankie, some 60 to 70 percent of native bees, most of them solitary rather than colonial species, make their nests in the ground and they need access to bare dirt to do so.  

Typically, what ground-nesting bees do is dig a little hole—some line it with bits of leaf or with polyester that they manufacture themselves—lay an egg or a few eggs in it, and provision the egg with a lunchbox of pollen and maybe nectar. This takes numerous trips to each nest, and she needs more than one spot to make a season’s worth of nests.  

Frankie recommends leaving half your garden’s soil open and bare. Seems to me you’d also have to keep it undisturbed and not dig up the babies, too. I’d suggest keeping at least the spaces underneath furniture, decks, and such features bare, just mulching places that get walked on and the rootways of plants. (And keep it a foot or so away from tree trunks too!)  

Unlike barbeque, it seems gardening isn’t a place to go whole hog about anything.