In Minecraft, How to create floating grass with command blocks

I am trying to build a puzzle map for some of my friends and having an issue with making floating grass/flowers with command blocks.

I can easily place 1 standing on its own ( https://i.stack.imgur.com/eGtjq.png ) (Using /setblock ~ ~2 ~ minecraft:tallgrass 2)

But whenever i use /setblock or /fill to create a line of these, it just makes the whole thing collapse. Is there any way for me to create something like this (https://i.stack.imgur.com/EWCmM.png) in 1.12.2 with command blocks? Thank you o/

Solution 1:

That /setblock doesn't always update the placed block is a bug. As soon as you change anything next to the flower, it breaks. Floating flowers or sand, extended pistons or open doors without power and other blocks in such weird states are not supposed to exist. In some cases you might be able to abuse bugs to create them, but not always.

Your options are:

• try finding a bug that allows you to create floating flowers (that takes a long time and tons of effort)
• use an external editor like MCEdit or NBTExplorer
• put barrier blocks below the flowers