I want to prepare 2 borders in our side yard from unused clay soil into perennial/shrub beds for planting in November/December (this year). I was planning to use trench composting by burying kitchen waste on a weekly basis and covering it with a thick (3") layer of mulch until planting time. However, after reading the responses in my other post (above), I think a better method would be to till the beds NOW with lots of organic matter, plant a cover crop with deep roots to break up the hard clay below, and replace the cover crop in the fall with the new perennials and shrubs. The soil is probably just perfect now for mixing -- still damp from recent rain, but not wet.

I have some questions about this:
1. In Fall, do I uproot the cover crops, or cut them off at ground level and mix them into the soil before planting?
2. Instead of planting a cover crop now, what if I cover the newly-tilled areas with a thick layer of organic mulch and keep it damp throughout summer?
3. If I go the route of cover crop, what other crop might I try for deep roots to break up the soil?

I am NOT new to gardening, but totally new to the practice of cover crops. I thought they were for veggie gardening only.

I agree that would be the simplest (and my original plan before I considered tench composting).... but would it be the most effective in terms of the depth of soil readiness?

However, since you won't have the option to plant a cover crop after the perennials go in the ground, I'd be tempted to try a summer cover crop this year -- then follow up with heavy composting and mulching around and between the perennials, once they're planted. Seems to me, that way you would get the best of both approaches.

Some cover crops root very deeply and widely. Those decaying roots can provide food for earthworms, and the resulting worm channels and casts can be great for easy root growth of your perennials, and for drainage.

Yes, earthworms feeding on surface compost and mulch layers will make their own deep channels too. But IMO you could enlist both the cover crop plant roots, and the surface residues of the cover crop once it's died back or cut down in the fall.

Some cover crops die back on their own, others need to be chopped down. If it was my garden and I had good access to a variety of cover crop seeds, I'd seed both a fast-growing, deep-rooted annual for carbon content (rye, etc.) and a legume or other nitrogen-fixing plant.

This fall you could chop the mature cover crop(s) down to soil level, lay down a light barrier of cardboard or newspaper, compost and mulch overtop -- then plant your perennials right through the cardboard/ newspaper into the enriched soil.

ATTRA's Overview of Cover Crops and Manures is a good place to look for general information; the SARE online textbook Managing Cover Crops Profitably provides more detailed info on specific cover crops.

All the best,
-Patrick

What I've read so far about cover crops barely scratches the surface; I hardly know where to begin. I read most (so far) of the ATTRA article and found it fascinating. I didn't realize they can be grown to loosen and prepare soil for perennial plants.

Well, I have already started layering OM on the new beds. So far, the mulch consists of a layer of newspapers (bottom), then about 2 inches of garden clipping run through the mower (browns), covered with a 1-2" layer of a high-nitrogen mix (chicken poop, horse manure, some browns --- the whole pile has a strong ammonia smell).

Today my husband suggested we plant summer veggies through the mulch, and I suggested a pumpkin to train laterally along the fence (on left side of photo). Or, could we sow beans or other cover crop right into the mulch?

In the photo, the new beds are the dark brown areas on the left, right, and the small patch in front of the large bare wall at the back. The big pile is the ammonia-smelling mulch. The round stones and flagstone are temporary; they will be replaced with decorative gravel. In the center of all that (where the wheelbarrow is resting) are 2 new apple trees; the onions (left foreground) and orange Nasturtiums will be removed, soon, and the whole area around the apples mulched with bark. This is our side yard which faces south-east.

I added more layers yesterday so the beds are now at least 6" deep in the middle. I would like to build them up to at least 18 inches to 2 feet ----- just as soon as my back and arms get a little rest. :-)

My question: Can I go ahead and plant a summer crop (seed or seedlings) straight into the layers, and then add more layers around them as they grow? The layers now include a rich (still ammonia-smelling) mulch which includes chicken poop, a finely-shredded woody mulch, shredded dry leaves, mowed fresh garden clippings, and green grass --- alternating layers of carbon and nitrogen.

All the Cabbage Plants you see in the beds got tossed on the pile before covering it with my compost.

I'm up for experimenting --- after all, I'm not planning a garden at the Getty Museum. :-)

Another question about planting pumpkins in these beds: If I plant pumpkin seeds/seedlings the entire length of each bed, we'll have vines eating the house. One vine seems adequate for each bed --- but will 1 plant develop enough root structure to break up the whole bed? Seems we'd need another crop to plant in the rest of the bed that won't take over the world or be suffocated by the pumpkin.

I don't know if that works (Pumpkins/Deep Roots), I have no experience with them (for that particular purpose).
But I know what does work and is manageable and overwinters..... Swiss Chard 2' long roots, big heavy tap roots.... they will break up concrete ;-)