Are you tired of hearing of hearing about the sunn hemp growing on the east half of Veg Hill? Sorry, we’re not, because we know what a full season of this delightful legume can mean to the fertility of our soil.
Here’s a picture we took of Amanda standing in the sunn hemp this week. Know that Amanda is about 5’5″ or 5’6″, and you get a sense of how tall we allowed the sunn hemp to get, we estimate about 12 feet at its tallest point. That’s fine for fixing nitrogen, which is one of the primary benefits served by a legume. So we were content to let it continue to grow until the frost got it.
Knowing the low fertility of our Longleaf Breeze native soil, we have been pleased at the way the sunn hemp has flourished. Not only is it generating lots of biomass and fixing nitrogen; it’s also creating a nice root system that we fully expect to make the soil more workable (the 50 cent word is “tilth”).
On Wednesday, though, while I was spreading some topsoil on Rows 6 and 7 for Amanda to use in planting, I noticed small yellow blossoms forming at the top of the sunn hemp. We’re not experienced gardeners, but even with our limited knowledge, we understand that flowers on a non-native species can be a bad thing. A very bad thing. The last thing either of us wants to do is to be the ones who go down in history as having introduced the new kudzu to the southeast!
We shared these two pics with Mallory Kelley, the Elmore County extension agent, at our Master Gardener class on Thursday. After some quick research, Mallory was able to reassure us that the sunn hemp will not propagate at our latitude (too cold to set seed). She did suggest that we go ahead and cut the sunn hemp, back, however, because of the risk that its main stem (analogous to a tree’s trunk) would get too big to decompose easily. So yesterday while Amanda worked feverishly to get Row 6 planted so we could install row cover (more to come on that), I cranked up the hedge trimmer and played Lil’ Paul Bunyan in the sunn hemp field.
Now I know what Mallory meant. We have sunn hemp main stems the width of my little finger; it’s hard to see how they will break down soon into usable biomass. The best we can hope for is that they will lay on top of the soil and act as mulch, reducing the velocity of any water runoff, and SLOWLY decay over a matter of a year or two. That may be just right, though. This whole process of organic growing is teaching us the virtue of making investments today that will reap benefits for years to come. We just hope we are good students.
Amanda narrates this video showing the sunn hemp before, during, and after the cutting; it runs about 2:20.