I tried using clover purchased from Peaceful Valley Farms this winter as a cover crop for my vegetable garden, but it only grew in widely dispersed spots once the weather warmed up a bit despite having spread the seed pretty heavily. I had thought it might grow OK over the winter because of our mild winters in Southern California. Not mild enough, apparently. I later sowed a California native, Phacelia tanacetifolia (which a quick Google search tells me I have misspelled before on this blog) which is naturally timed to sprout and grow through the fall and winter. Success!
While looking for cover crops on the Peaceful Valley website (the source for my clover seeds) I came across mention of Phacelia tanacetifolia as a cover crop. Since I had plenty of seed left over from last year's seed harvest I gave it a try in my vegetable garden.
Use of P. tanacetifolia as a cover crop isn't widespread in the US, but there's an awareness that maybe we're overlooking a good thing:
Phacelia tanacetifolia is a versatile plant that is used extensively in Europe, both as a cover crop and as bee forage. It is also being increasingly used in California – especially in vineyards. Phacelia is quick to grow and flower and grows well in dry soil. It does a good job of limiting nitrate leaching when planted in early fall. It winterkills at about 18°F. In cooler regions, it can be used as a between cash crops cover crop in the summer. Phacelia is listed as one of the top 20 honey-producing flowers for honeybees and is also highly attractive to bumblebees and syrphid (hover) flies. Phacelia's habit of flowering abundantly and for a long period can increase beneficial insect numbers and diversity, because it provides high quality nectar and pollen. It's also useful as a cut flower with its unusual and attractive blooms, strong stems, and long vaselife. Because phacelia germinates well at cool temperatures and grows quickly, cut flowers can be available by mid-spring. ref.
I applied the seed to the densest and heaviest of soils in my raised garden beds after spreading some compost on top. This is a bed that had previously not seen many amendments and the soil there is more clay-like than at the other end of the vegetable garden.
At first I feared that it wouldn't grow, but apparently the winter exposure isn't as direct in this bed as in my front yard where the P. tanacetifolia started weeks earlier. Eventually it grew quite well.
Here it is, with Ollalieberries on the fence in the background. I had already started on the demo in this photo - see my shovel handle sticking out.
Last week I cut it down at the ground and composted it in place with a top dressing of rotted leaves. I've kept it damp and it appears to be ready to plant, so today I put in cucumbers.
Who knew cover cropping with natives would be so easy?