How to Grow Portobello Mushrooms | Agaricus Bisporus Cultivation Step by Step Portobello button mushrooms are not easy to grow and I have searched for years to find an easy way to grow them and could never find videos actually showing the whole process. I made this video to help all the people who also could not find proper tutorials. Many written tutorials say that you must use compost as a substrate which can be very hard to make or find the right one, In my method I do not use compost, only h