Looking through the code there are a few issues. Firstly there is a logic error in the plant code which means the maxmass limit is never applied. Secondly the arithmetic for growth rates is way too fast, resulting in reaching high values way too quickly.
Looking through the code there are a few issues. Firstly there is a logic error in the plant code which means the maxmass limit is never applied. Secondly the arithmetic for growth rates is way too fast, resulting in reaching high values way too quickly.