I am a soil girl. I typically like to have a good base of soil with amendments for growing garden vegetables. So when I started working at a compost facility, I got asked often if it is okay to grow in straight compost. It seems to go against my grain to confirm that, but it after some experimenting, I believe this is possible now.
There are some good reasons why it might be good to plan to grow in straight compost. Many gardeners that have small backyards are able to make compost with grass clippings, leaves, twigs and food waste. Adding soil would be an expense that needs to purchased and brought in. There are techniques such as the lasagna compost garden that can be easily done in a backyard as a base for growing plants in. In this case, just watch you plants and see how they are growing and if they are surviving. This type of compost may be too rich or lacking nutrients but if the plant is healthy and growing, then you have success! We grew the sample bean plant above in the picture in straight compost. This is a check to see if our compost is good and we feel this was very successful. Just keep the compost well watered as it tends to get hydrophobic.
As I just mentioned, compost tends to become hydrophobic. In other words, it will dry out fast and then plants can be lacking in water. As long as compost is kept damp, it will be easier to continually water and absorb that water. If it gets dried then the water will just push right through it and not absorb into the compost.