We have been unable to reproduce this issue internally. As an aid to tracking down the cause of this issue, we've added extra information in the tooltip for growing plants. When the plant is receiving the greenhouse bonus, the tooltip will include the message "Growth Rate x2.0". This change is available now on the latest QA build. Please join us on the QA server - test out your placed planting beds, taking note of when the bonus is applied and not applied. If we can determine the cause, hopefully we'll be able to get a fix out for the beginning of R70.