Cover Cropping with Sunn Hemp
On this week’s episode, Travis and Greg have a patch of Sunn Hemp which is a warm-season cover crop in the vegetable garden. This cover crop variety is a legume which means it is related to crops like beans, peas, peanuts, and hairy vetch. This is a beneficial cover crop that allows you to add a significant amount of nitrogen, suppress weeds, and quality organic matter back into the garden soils. However, compared to other warm-season varieties the Sunn Hemp is the only nitrogen fixer cover crop. As a nitrogen fixer, it is able to grab nitrogen from the atmosphere and convert it into your garden soil. This fixer is important in the garden because when you get rid of the cover crop you will gain lots of available nitrogen for the next vegetable crop you plant in that area. Some recent studies have shown that Sunn Hemp can fix up to 100 pounds of nitrogen per acre which is excellent when planting heavy feeder crops like onions and corn. Sunn Hemp should be planted when soil temperatures are around 65 to 70 degrees Fahrenheit. When planting it can be broadcasted or with a precision planter like the garden seeder. It ultimately grows extremely fast and typically reaches maturity in 8 to 12 weeks. This cover crop variety is pretty much maintenance-free and does not take a lot of effort to grow in the area. Since it grows so quickly it suppresses weed pressures by outpacing weed germination which is a major benefit in the vegetable garden. Like all cover crops, Sunn Hemp should be cut or mowed before it reaches seed to prevent reseeding issues in the future growing seasons. The guys mention that the best time to cut or mow it into the soils is during the woody stage.
Benefit of Using Silage Tarps
However, Travis is going to try to extinguish this cover crop in the garden using silage tarps. Before adding the silage tarp to the area, Greg will take his flair mower to mow down the cover crop. Once the Sunn Hemp is laid flat it is ready to add the new silage tarp on top. Depending on the size of your garden, we offer a 30′ x 40′ and a 40′ x 50′ Silage Tarp. Using silage tarps as a garden technique is called occultation which essentially means that the tarp is blocking the sun from touching the soil. Therefore, the lack of sunlight penetrating the soil creates a warm, dark, moist environment in the vegetable garden. This environment facilitates the germination of weed seeds that quickly die due to the lack of sunlight. It also creates a dynamic soil life with abundant earthworm and beneficial bacterial populations. Another benefit of using silage tarps is when creating a new vegetable garden spot. The tarp can be used to kill existing grass and create a virtually weed-free garden area.