The above is a good article, but two exceptions need to be made for the Pacific Northwest or in areas where it rains a lot. Here, in fall, most people like to cover their garden beds with loose, clear plastic to keep most of the rain off/out of their garden soil. The reason for this is because it rains enough here that the rain actually leaches out and washes away the nutrients most garden plants need to survive, and acidifies the soil.
That's great for things that grow naturally here such as pine trees, rhododendrons, blueberries, blackberries, huckleberries, elderberries, and so on. They love an acidic soil and do fine on the little bit of nitrogen present in the soil. But for the organic vegetable gardener, especially in the hills, we've spent a lot of time, energy and sometimes money to amend the soil to get enough nutrients and the right pH needed for vegetables. My husband and I have hand shoveled literally tons of leaf compost, nurtured thousands of worms and collected tons--no joke, about 20 tons--of their vermicastings. Some of it we sold, but a lot of it ended up amending parts of our 6 acres, but especially our garden area. We don't want the rain to wash all our hard work away.
|Garden bed all tilled and almost ready for its plastic cover--|
lots of wind blowing leaves on it today though.
The second thing we need to do in the Pacific Northwest is to either skip the mulch, or go ahead and till it in with our organic manures before we cover our beds. The reason for that is: SLUGS. They thrive here because of the rain, and a bed of mulch is a great place for a slug because some slugs eat certain mulches such as leaf mulch. It's also an ideal place for them to hide out if we should have a break in the usually continuous winter precipitation, or if it snows, the mulch will be a warm haven for them. Worst of all, it's a perfect place for them to lay their eggs.
The tarp or plastic will also contribute to the survival of the slugs, but at least it won't be a food source for them. Indeed, the battle with slugs is an ongoing one here for gardeners in the Pacific Northwest. Slugs are so pervasive and destructive to garden plants that OMRI continues to approve the use of ferric phosphate as slug and snail bait "if the requirements of 205.206(e) are met..." for organic gardening.