I commented on the main page but thought I could also post this issue here. Hope this is okay. I opened a server and planted a field of 20 grass with every available grid. Dug one out in the middle from each. Moused over with the grid to check if I could still re-plant it. Logged out. After relog I checked again. The grid no longer shows the free spot in the middle as available. The free spots around the fields also changed. Notice the missing gaps and additional blocked places.

It appears the only reliable grid is the plain square.

http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946022
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946807

http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946091
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946733

http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946142
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946654

http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946207
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946408

http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946269
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946476

http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946324
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1215946570