We have been using thick mulch of year old unsold/unused straw (the large 300kg rolls) from local farms for nearly 4 years to reclaim/dock kill areas of our property as well as winter mulch our fodder growing field and haveb been very successful. It has usually been at least 1 year old if not 2, and well weathered barley or wheat straw originally grown for winter bedding on local dairy farms... We still get some seed germination but its not particularly strong and in the larger areas we keep it down by the occasional going over with the brush cutter. We also mulch our raised beds in autumn (before winter weather, snow, etc.) after clearing using regular size bales - if we have planted the beds (e.g. onions, leeks, garlic, spinach, spring cabbage) we "fluff" the straw up, but still 12 inches or so thick. If the beds are just being overwintered for spring planting we lay down the flakes/slices as others have mentioned. The raised beds are easy to weed out any germinating seeds and they never amount to anything.
We have never cleared the straw away before planting, but planted through it in the beds - or in the case of field/row crops like beets, mangels, potatoes, field beans, corn, etc. we simply pull back the straw to open up a row, sow the seeds and tamp them in, then pull the straw back over them. We haven't cleared any straw away for a few years, although we use our breeding trio of pigs (and any offspring) as well as our chickens, ducks and geese to go through our fodder field in autumn, then rake it over and roll out more bales on top of it. It builds up great soil that is easy to work - and the critters also process huge amounts of with digging and stomping etc.
i can get bails of alfalfa hay that i would like to use to mulch my lettuce beds in a greenhouse this spring. any thoughts or other ideas?
- I wouldn't recommend using alfalfa hay or regular hay for mulching if you want to avoid seed germination - as I'm sure you know hay is cut with the seeds on whereas straw is the by-product of removing the grain (seeds) from the cereal. So they will have many more seeds even if the hay is a couple of years old. If we do get any free or cheap old hay/alfalfa we use that as mulch/weed killer in our orchard, paddock (around trees) and tree nursery where germinating seeds aren't a problem as they eventually just add to the grass cover.
Best of luck!!!