A plague of locusts

Folks have the unkindest things to say about locusts. Whether it's the insect scourge or the trees known as "honey" or "black" locust, there is abundant opprobrium for all these fine organisms.

Locust insects, like deer, can be fattened on your food, especially grain, before you eat them. Their appetite for agricultural products is at the root of their unpopularity. Fried, smoked or dried, they have been a staple since at least John the Baptist dipped them in wild honey.

Speaking of honey, the honey locust has pods that are delicious to sloths. It also bristles with thorns long enough to kill a man and strong enough to puncture tires. I'm not here to say anything in defense of honey locusts, though I have an open mind about their possible virtues.

The black locust is similarly thorny, though not quite so forbiddingly so. Its pods are said to taste like sugar snap peas. It is a nitrogen-fixing tree with very valuable wood that feeds everything from insects to pollinators to deer.

I should mention here that it is on the King County Weeds of Concern list. Like honey locust, it is aggressively expansive and one tree can spread as far as 20 feet away via root runners.

An eruptive grove of thorny trees hard enough to dull chainsaws explains why some curse this restorative plant. Particularly in the built environment, black locust can make for a lot of bad blood and burst boundaries.

Those same properties make it a splendid healer of abused land. I planted several black locusts years ago in partial shade to colonize an eroding sandy hillside, and so far they have done nothing of the sort.

One out of five died and the rest are growing steadily, each having put on a foot since 2019. They're growing in an area that lacks alder, and I hoped they would spread by runners to hold the soil while fixing nitrogen.

In seven years, black locust can provide outstanding firewood, and in 20 years it can be milled for lumber. This wood resists rot better than pressure-treated lumber while at the same time it's safe enough for children's picnic tables. It is often used as trellising in organic vineyards, or as fence posts.

Plenty of articles will warn you about growing it, but those that I found were referring to suburbs and cities. Any pioneer plant, which by definition wants to enrich conditions for successor trees to come, should be carefully considered before siting in the built environment.

On a sandy hillside under a canopy of big-leaf maple, it's hard to see black locust becoming "invasive." Along a steep narrow driveway, supporting bamboo plantings, it can only descend a 50-degree slope or infiltrate the gravel and get pulverized.

Nearby properties are unlikely to be affected. Seed pods don't travel well via wind or birds, and germination rates are poor besides.

Akiva Silver, in the excellent "Trees of Power: Ten Essential Arboreal Allies," says black locust will shade itself out within 80 years, leaving rich black soil for native rooting plants. If you aren't sure, just mow down the root sprouts as they come up and cut the tree for firewood while it's still a manageable size. It will be building your soil no matter what you do to it.

David Ahlgren, permaculture instructor and earthwork specialist, likes to say that "where there is a thorn, there is an edge." Like Himalayan blackberry grows in disturbed areas at the interface between humanity and wilderness, protecting these demilitarized zones with a hedge of thorns and sprawling roots, black locust can build back better - but without all the hot air and haggling.