There are people who plant in lasagna gardens, and those are basically compost (not necessarily even finished compost. I think the biggest concern for some types of vegetables is whether the compost would be so soft that some plants might fall over. I don't know this for sure, and maybe the lasagna gardeners can help with that answer, but plants that grow in 100% compost can be very healthy.

we plant directly into mushroom compost though it isn't broken down yet.

i can't see any problems compost should have a variety of nutrients in it.

anyhow you are welcome to check our gardens on our site and see how we do it.

len

Here is a link that might be useful: len's garden page

I planted a garden once in just compost and the only problem I had was keeping up with the plants. They were healthier than I was. My cosmos which usually is about 24" tall were over 6' tall, they reached the eaves of the house. My roses nearby were so big that the blooms had to be staked because they were so heavy they broke the stems they grew on. There were a couple of cucumber seeds in the compost that sprouted behind the cosmos and at first I thought I had an alligator lurking in the garden, but it turned out to be just a giant cucumber. Or rather it was 19 giant cucumbers, those cukes were hard to pawn off on the neighbors cause the kids were afraid of them. If you have good compost, you don't need to add anything else to the growing mix-you already have the best growing medium there is. Cheryl

I had same experience as seamommy, lots of tall plants with loads of leaves. Just not enough flowers and fruits. I had to learn to balance compost with phosphate, lime, calcium, etc. Now I just use my soil testing kit to test compost first, then add whatever each bed needs (extra calcium for the tomatoes, for example -- eggshells I save all winter).

Organicburrito, what kind of soil test kit do you use on your compost?

I saw burro and thought burrito. I guess I'm hungry. My apologies.

Hey julianna don't worry! I don't mind being confused with delicious food. I love Mex food, and just made black bean enchiladas with green salsa. Yum.

I use test in link below. It's sold pretty widely.

When I first built my raised beds, I sent away for Penn State soil test kit, and got full professional analysis. So now I just have to do my cheap small test every year. I test soil and test compost. So far, so great.

Here is a link that might be useful: Soil test kit

A good soil is a combination of sand, clay, silt, organic matter, air and water. Compost provides the organic matter component of soil, but it dosn't replace soil.

Over time, a raised bed of nothing but compost will shrink down to nothing. I would add some soil before I planted anything.

I think of compost as a soil amendment, not as a soil replacement. I agree with joepyeweed. Also, I've planted in lasagna beds successfully but had to water WAY more often than planting in the ground until the layers shrunk and the plants rooted in the soil.

I've planted in 90+% compost and had great success. Incredible growth and production, but they needed staking as stated above.

Lots of growth and no fruit is too much N, usually. Less greens in the compost and I bet it would rock.

-pH