I have the opportunity to garden on my neighbors lawn this year. The area is 30×25, so I am planning on having 5×30 inch beds separated by walkways.
The only problem is that I just got permission now, and it is currently all grass and weeds. Because the area is quite large, I think getting cardboard to smother the grass is out of the question. I don’t have a tiller and prefer to not till.
My neighbor told me I should spread a 3 inch layer of wood chips and then top it with 6-8 inches of a soil and compost mix because that should be enough to smother the weeds and still allow me to plant this year.
My worry with this is that the fresh wood chips will have too much carbon and will also rob the soil/compost of nitrogen. Is that correct thinking?
Would 6-8 inches of topsoil and compost just right in top of the grass be enough to just plant in this year? The soil is clay.
Thank you so much for your help,
Trust you are well
Congratulations on taking on this project
You can save lots of time and physical work because you do not actually have to dig up the lawn/weeds at all. The are many options available to you, including:
You could just turn over the lawn and weeds by cutting it into pieces and turning the clumps upside down. The old lawn will decompose into wonderful nutritious soil for your vegetables, and you could lay the 6-8 inches of topsoil/compost mix on top of that. Although you would have to do some weeding, hopefully it would be minimal because of the depth of the overturned grass. Turf Grass Removal Methods illustrates the “slice and removal method”
For large areas you may wish to consider soil solarization. This can be accomplished by covering the area with either clear or black plastic. Black plastic is used where the intent is to starve the weeds to death by preventing them from photosynthesizing, while clear plastic is used where you want to “cook” the weeds to death. Please refer to the following archived post for further information on this process, Putting a small garden to rest
“Covering the ground with thick black plastic is an effective way to kill weeds. At first the weeds will begin to grow rapidly due to the heat under the black plastic however over time they will die from lack of food. Essentially, the weeds will starve since they cannot produce food through photosynthesis and eventually will exhaust their food supply and starve. This method takes time and will only work as long as no light reaches the plant.
Another effective non-chemical technique to eradicate weeds is through solarization. According to the University of California Integrated Pest Management
“The method involves heating the soil by covering it with clear plastic for four to six weeks during a hot period of the year and when the soil will receive the most direct sunlight. Plastic tarps allow the sun’s radiant energy to be trapped in soil, heating the top 12 to 18 inches to temperatures lethal to a wide range of soilborne pests; including weeds, plant pathogens, nematodes, and insects. When properly done, the top layers of soil will heat up to as high as 140°F, depending on the geographic location. Soil moisture is important in this process, as wet soil conducts heat better than dry soil. Moisture also makes soil pests, weakened by the heat, more vulnerable to attack by beneficial soil microorganisms during and after treatment.”
In addition, solarization stimulates the release of nutrients from organic matter present in the the soil. It is especially effective for treating garden soils, where the intent is to plant vegetables, herbs, and flowers.”
The last option is what is known as lasagna gardening. You begin by laying down a thick layer of cardboard ontop of the area will smother the weeds. The garden bed then gets built up from there with layers of manure, shredded leaves and good compost. Lasagna gardening: Build Soil and Get Rid of Weeds and Sheet mulching- aka lasagna composting provides step by step instruction on how to build a lasagna garden. Things to consider include effort, price, permanence, etc…You could do this alone or in combination with the “overturning” technique above.
Now a days the approach is not to till the ground. Rototilling can be detrimental to the soil ecosystem by disrupting the mycorrhizal connections that exist underground. Also tilling can uncover dormant weed seeds which once exposed to sunlight will begin to germinate.
If you want to read more about the pros and cons of tillage, see below.
Minimal Soil Disturbance : Conservation Tillage
You may be correct with the issue of the wood chips with respect to nitrogen. The jury seems to be out, see for example here:
I take it you are planting directly into the soil and not into containers – as 6-8 inches would not be enough soil depth generally for containers unless they were open to the ground below.
Since your soil is clay it is always good to amend your soil with as much organic matter/amendments as you can. See for example:
Good luck in the journey and enjoy
March 15, 2021