Overall your plan sounds good, except when you say you will mulch with clipped grass -- I only use dry brown leaves and pine needles, nothing green.

re unfinished compost - I just read that unfinished compost 'consumes' nitrogen while it is still in the process of 'finishing' -- if that is true, then your plants will be robbed of the nutrients

If you are using unfinished compost as a mulch you will NOT have to worry about nitrogen being robbed from the soil. If you had tilled it in, you WOULD be losing the available nitrogen for the period of time it took to break it down.

Also, I see no problems with mulching with grass clippings.

g'day marla,

teh nitrogen issue only comes about when uncomposted or partially composted material is dug into the soil and then pnaed into, if you are a tiller and it is going to sit over winter i should imagine then there is never going to be any waorries, if you spread raw or unfinished organic matter around on teh surface the plants therein will not be affected by any nitrogen take up.

taka a look at our presentations there maybe some hints there for you, for us we preffer using hay or straw for mulch, grass clippings could be spread under the mulch. have always found a good cover of mulch keeps the medium below it warmer in heavy frosts.

len

Here is a link that might be useful: lens straw bale garden

Good advice so far. I agree that making a 'compost pre-mix' and mulching your garden beds in the fall is probably the ideal situation. Connecticut gets a lot of rain, so you can probably get away with a thicker layer than would be advisable for other parts of the country.

My tillage practices evolve toward no-till after I have created a garden bed. That includes applying mulches and compost to the surface of the soil. In the spring, finished compost, straw and grass clippings, and in the fall, unfinished compost and mulches.

I've made the mistake of tilling unfinished compost into the soil. Many crops simply wouldn't germinate; peas (!), carrots, the tomato and pepper transplants struggled, the melons died.

Several of the community gardens in this area have raised beds that were filled with a manufactured soil. We have a company here that is dredging a lake bottom of the accumulated organic matter that has threatened that lake with eutrophication and then mixes that OM with sand and sells it as soil, not "topsoil" or "garden" soil, just soil. The OM dredged from the lake bottom is dewatered and then finely ground before being added to the sand and if you got some of this and then left it exposed to the rain the rain would wash the OM out of this soil leaving yuou with just sand, unless you added more OM to that soil.
You will find that if you build up those raised beds with just organic matter you will need to add to them all summer long as the OM is digested by the bacteria. I find this true in the containers where only compost is used as the growing medium.

Yes, compost and any other OM will shrink down to almost nothing. If you want the bed to be raised above the surrounding level in your yard you will have to add some actual soil. Lots of compost and other OM in the form of mulch is great, but if you've never built a lasagna bed before, you will be shocked at how much it shrinks in volume. If you add a foot of OM, chances are good that the level will return to it's present spot, or maybe an inch higher, within a year.

Lots of OM is good, but you can't "make dirt".

Karen

Thanks for the advice and ideas.

I have some "topsoil" that we bought a while back. It is very sandy, very little OM. If I were to use this along with my mixed-lasagna idea, would you suggest adding the topsoil to the bottom of the raised bed, then topping it with the mixed OM materials? Or, should the topsoil and OM materials just be all mixed together?

Thanks!

Last fall I FILLED TEO 8' ling raised beds with all the og=rganick meterial that i could lay my hands on. I used maple leaves, grass clippings,bales of straw, vegetable stalks, coffee grinds, peat moss and unfinished compost. In 25+ years of gardening my vegetables have nevver looked better. It will shrind,my beds are one foot deep and I filled them at least 4 to 6 inches over that, I used netting to keep it in place. By spring it was level with the top edge when I planted it was down another 2". Since then I have backfilled the beds with grass clippings and compost to top it off.

Anthony

I built a lasagna bed this spring and used a good amount of partially finished compost along with finished compost, regular ground soil, leaves, and whatever else was lying around. I had read somewhere that you could plant directly into unfinished compost so I thought I'd give it a try, plus there was no other way for me to get soil decent enough to plant. The bed started out about 18" and is now down to 6-8". I thought it would shrink more! I didn't direct seed anything in it but all my transplanted tomatoes and peppers thrived! I had my largest tomato plant yet! I actually worried it was getting too much nitrogen because of all the gorgeous foliage, but I ended up with lots of fruit as well. The moral of this story - there's always a conflicting opinion!