Over the winter, I’ve spent some time researching cover crops for upcoming projects in 2018. At the most basic level, a cover crop is crop that is grown not for cash, but for some kind of soil benefit. The most frequently cited use for cover crops and the one most people are familiar with is to hold soil in place/prevent erosion through extensive root systems.
However, the world of cover crops is much more extensive than just that. For instance, the bean family is used to bring nitrogen into the soil from literally thin air. Daikon radishes are used to penetrate deep into the depths of compacted soil up to six feet. Some plants like rye have what are called “allelopathic” properties that inhibit seeds (like weeds) from germinating. And still others grow so fast and make such dense plantings that they choke out weeds. So when working with cover crops, the choice is really application and time based.
To that point, early springtime can be a difficult to get a cover crop sown because the soils have not warmed up yet. In very general terms, seeds like warm temperatures to germinate. It is with this set of constraints that I learned about Phacelia, which seems like the perfect cool season early cover crop.
Phacelia is native to the southwestern part of the United States. However, its use as a cover crop was pioneered in Europe. Today, most of the United States' Phacelia is imported and is a little pricey because of this.
After price-tag shock however, Phacelia does indeed have its benefits. The first of which is that it germinates in cool temperatures between 50-68 degrees Fahrenheit. This is a cool enough that it can get started and out compete weeds when planted densely. Second, its root system is an excellent conditioner of topsoil, scavenging nitrogen and calcium. Additionally, it tolerates a wide range of soil pH’s from 6.4 to 8.6. Here in Cleveland, I’ve seen many soil tests come back in the high pH range. It’s nice to know there’s a cover crop for these alkaline soils.
In addition to all these soil benefits, Phacelia has another awesome conservation benefit. It’s an amazing insectary plant, which means pollinators love it! With all the headlines about bee populations in decline, this seems like a perfect fit for pollinator-habitat plantings, as well as an excellent cover crop choice.
Now that it's almost spring, how will you be readying your soil?
Blog Author: Justin Husher, Horticulture Specialist