I don't know why but kelp keeps breaking when I place it.

• I am on creative mode.
• I made a one-block width column of water 20 blocks tall
• the kelp will not place in there
• Another column 3x3 width, 20 blocks of water will not allow one block of kelp in the center. 

There is nothing in the Minecraft Wiki that specifies the type of block it needs to be placed on or the amount of space that it needs under water...

I don't know why it keeps breaking!

Thank you!