Usually you refeed the cultures with a complete change of medium every 3 days / 2 times a week.

Here is a detailed protocol by invitrogen thermofisher:

http://tools.thermofisher.com/downloads/HumanMesenchymalStemCell_MSC_ExpansionProtocol.pdf

Hi Dominik, Thanks for your answer. The link is indeed very helpful. In regular cell culture I would also sub culture or change medium every 3 days or so. I was wondering if the culture for the CFU-F assay could be done without changing medium for two weeks since you only have very few cells to start with and they might need the products (e.g. growth factors) produced during culture?

I guess it would depend on the medium you use for the culture. I found this link where they leave the cells for 10-15 days but it does mention that you could change half the medium on day 7 if needed.

https://cdn.stemcell.com/media/files/pis/28066-PIS_1_7_0.pdf?_ga=2.33469630.1076480911.1520373017-172601174.1479328993