Sunn Hemp is One of My Favorite Cover Crops!

Sunn hemp has fast become one of my favorite summer cover crops. This organic plot at the Texas A&M AgriLife Stephenville Research Center is already up to my elbow and still growing.

The value is easy to see in the picture below. A seed tube in the drill stopped up, leaving a space where the sun could get to the soil, so we now have a thick strip of weedy grasses. Also, the Sunn Hemp plant itself is known to suppress weeds – if it gets planted!!

In the picture below you can see that the Sunn Hemp made a good stand so that the canopy is already shading the soil and suppressing weeds before they can get established. As an aside, this field has a lot of yellow nutsedge, but the Sunn Hemp is keeping it shaded and suppressed too. It won’t take it out, but it will help!

I could pretty much step into any part of the Sunn Hemp planted area and find bare soil with just a few minor purslane weeds under the canopy.

This is just a demonstration for why cover crop establishment matters. A cover crop only works where it gets planted and this field had been a weedy mess for a couple of years. Because this is now part of an organic system, we needed a strong stand of sunn hemp can act like a living weed barrier while also producing biomass and adding nitrogen back to the system. Research and Extension publications commonly report rapid sunn hemp growth, strong biomass production, nitrogen contribution, and weed suppression benefits.¹

One more benefit for Texas organic farmers: sunn hemp is a tropical legume and is not normally a reseeding weed problem in our systems. It can get stemmy so you may want to cut it occasionally and have it regrow, which it does quite readily. Also, I have planted it several times with a sudangrass and the two grow together well and can be harvested as hay.