|Deep-mulching in Alpine Garden - 9.5 weeks after we broke ground in 2009|
"I like the idea of the thick hay-bed, but as far as prep work, do you need to pull beds of grass up before laying it down, or will it kill off well established grasses? For example, could you lay it down and then arrange and build beds the next year, or should you clear and arrange beds and then lay down the hay?"
The short answer is, if you have the luxury of waiting a year, you can lay the hay or straw down thick enough to choke out the majority of grasses or weeds below without tilling . If you're eager to begin using a garden area that has established grasses, you will have more success in the short-run if you till first. Here's how things have unfolded in our two garden plots:
The Alpine Garden - 2009 - Our friend Steve Rose subsoiled and then tilled the surface lawn to a depth of 8" with a heavy tractor. We mulched heavily 4" to 6" with whole flakes (a solid mat) of hay and straw throughout the growing season and bedded the gardens down with an equally heavy coating of leaves in the fall and early winter.
People warned us that mulching with hay would cause serious weed problems from the hay seeds falling into our garden beds and sprouting but this did not occur. The secret is in how deep the mulch is laid. With very deep mulch, weeds sprouting from the soil-level exhaust themselves before they can reach sunlight. Those that sprout in the mulch itself are very easily pulled out as their roots do not reach the soil below or, if lots of grass is sprouting, slip a pitch fork under the flake and turn it 'roots to the sun'.
|Alpine Garden - 2nd year - Minimal tilling, Heavy mulching|
We are now in our third spring. We will be doing little or no tilling. We have established a thriving worm population and don't wish to disturb their world. In places where they have eaten through all the mulch from last fall, the surface is noticeably covered with little mounds of their castings. In places you can see the tiny holes where they surfaced at night and returned to their subterranean domains each morning. As we transplant our spring crops, we disturb this eco-system as little as possible. We move the mulch aside enough to accommodate the plantings. In some cases pulling aside a whole swath of mulch, in other cases only exposing a hole big enough for the plant. The worms' tunnels provide easy pathways for roots to find their way, and they are filled with the worms' castings. Water and oxygen can make their way into the soil through these same pathways.
|Worm castings on surface of soil.|
Our garden plot in Monroe has a slightly different history. It was not tilled nearly as thoroughly in its first year (2010). We had a cold, wet spring and by the time the ground was dry enough to till, it was time to plant many of the crops that were becoming root-bound in their pots. Whereas Alpine was worked to a depth of maybe 8" to 10", Steve was only able to till down about 4" in Monroe. This resulted in a lot more weeds to deal with! Even though the paths were deeply mulched, we had lots of weeds coming up in the beds themselves. Still, we had a very productive first year.
|Monroe garden - 1st year - Heavily mulched.|
|Monroe Garden - April 2011 (2nd year). Chris is peeling away a row of mulch and piling in adjacent path for this year's potatoes.|
The Benefits of Deep Mulching
And please read our post about Herbicide Contamination of Compost, Manure and Mulch