When we pull harvest from the garden, week after week, we are taking from the garden ecosystem. We are taking from the soil.
Here in Southern California, where we can harvest year-round (with a seasonally-appropriate crop mix), that means we are taking from the soil constantly. In order to maintain basic soil fertility, we must always be building-building-building up our soil.
That means compost, it means mulch, it means worm castings, it means doing all the things that cultivate rich, alive, healthy organic garden soil.
Here are some resources we mentioned during my soil-building garden classes:
“Feed your soil. Your soil feeds your plants, and your plants feed you.” (paraphrasing John Jeavons)
Feed your soil organisms. They are the ones who feed your plants (according to Lowenfels), and your plants feed you!
SLIDES for my March 13, 2022 soil-building class (coming soon)
Think of yourself as being a “worm farmer” with the goal of growing bountiful soil life.
“Living soil” means an entire ecosystem of organisms – eating, pooping, reproducing, and interacting with all the other species. So you can’t just go to a garden center and buy a carton of “earthworms,” dump it in, and call it done.
For anything you might consider adding to the garden, ask yourself “what will this do for the soil critters? how can I benefit them?” The answer will guide you to best practices.
Food for your soil critters
things that used to be plants
Fine-textured, mostly decomposed. in other words, you can’t tell what it used to be.
exception: California native plants. Habitat restoration expert Nicholas Hummingbird teaches that soil mixes are too rich for our native plants. For these plants, don’t add compost. Instead, plant directly into the existing soil you have.
Protection for your soil critters, plus long-term food supply.
Coarse-textured, not decomposed. Examples: wood chips, straw, shredded paper.
layer on top of your soil, like “putting a quilt on your bed”
Lowenfels & Lewis teach us that trees and perennials crave carbonaceous mulch like wood chips. For annuals like vegetables, use the more-easily-broken-down mulches, like straw, leaves, paper.
Habitat restoration expert Nicholas Hummingbird teaches that California native plants shouldn’t be mulched. Instead, plant groundcover native plants to shade your soil.
green mulch versus cover cropping
the term “green mulch” is often used for the practice of growing beneficial plants in between areas – for instance growing clover between rows of fruit trees, where the clover is periodically cut and left to decompose. It isn’t really something that fits into urban gardening practices.
the term “cover cropping” refers to the practice of growing restorative plants on a bed that is fallow, or not-being-used. If you are skipping a season (for instance you only grow vegetables in the summer season) you should consider growing legumes or clover as a cover crop when your garden is out-of-use.
great cover crops for Southern California’s cool season: peas, fava beans, clover, buckwheat
if you have Bermuda grass in your garden, there is no question. You must remove the Bermuda, which unfortunately means you must disturb your soil. How do you get rid of Bermuda grass?
if your garden is (miraculously) Bermuda-grass-free, or a section of your garden is Bermuda-grass-free, you have the option of trying no-till. To do this, layer additions of compost on top of your existing garden soil. The larger organisms within the soil life — such as earthworms — will do the tilling for you. (trust them)
Geologic “soil shed”
the basic “bones” of your garden
Zoom out on Google maps: what are the massive, geologic-scale, pre-existing (and unalterable) conditions within which your garden exists? (examples: river bottom, sand dune, beach, ancient riverbottom/sandstone, volcanic or glacial deposit)
Much of Westchester is a sand dune. When you view it in “zoom out” perspective, it’s clearly part of a series of dunes which are visible west of Pershing, west of LAX.
Much of Culver City, Marina del Rey, Playa Vista is mostly clay. Before L.A. was built out, the L.A. River alternated between reaching the ocean via San Pedro, and reaching the ocean via Ballona Creek.
Starting a New Garden – here’s what we did with “virgin soil” to jump-start the Community Garden at Holy Nativity the very first year. (Once your garden is established, you don’t have to do these things)