How to get my dirt to not turn into a grass block?

Question

So I made a flat world and I use it for displaying every single block and item in the game using the order of the creative inventory (excluding items accessible via commands). A certain order is dirt blocks and different types.

In the order, a certain bit of it is Dirt, Coarse Dirt, and Grass Block. They are all beside each other, and that's what I like. However, I'm worried that the dirt will turn into a grass block even if the coarse dirt is in the way. So I set it the Random Tick Speed to 1000 (enough to make a fast process of turning it into a grass block without making it too laggy due to high tick speed).

So I thought of ways to overcome this:

1. Remove the block under the dirt block. Didn't work.
2. Place the dirt in y = 5 (assuming everything else is in y = 4). Works, but I don't want this. I want every block and item on y = 4.
3. Place something on it. Transparent items won't work, but other blocks and water works, but I don't want this either. I want to walk on the blocks with no obstruction.

This list will continue to be updated as response to answers given.

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Then I found this answer on a question having the exact opposite goal. All the blocks and items are located in the same X-level to actually be viewed in front of the player spawned Also, the given 1st rule in the image is not something I want to do. I kept the world Always Day to shine everything with a bright sky for better display, and I also want to record a video of me walking on the line of blocks and items.

I thought of using commands, but I can't be sure if /setblock would even help stop the block from turning into something else.

Are there other ways on how I can stop my dirt block to turn into a grass block?

Answer 1

If you space all of the blocks out with one block between them, it would still look good and the grass would not spread as long as there isn’t grass on the blocks below and to the side of the block. Otherwise, you could change up the order of the blocks - though I’m sure this might ruin the display. I’m not great with technical stuff, but you could try lowering the random tick speed to 0... this might last a while. Hope this helps! Edit: you would have to use barrier blocks in between the blocks to run on them with gaps in between. This would mean you couldn’t display barrier blocks, but because they’re invisible it wouldn’t add all that much.

Answer 2

I said that I tried removing the block underneath the dirt. It's better doing it in a 3x3 wide hole. It shouldn't be too deep though, and I can easily cover it up with green carpet, because it is the closest to something that looks like grass.

I can't show the image now as I don't know how to use Bluetooth properly and I've been using my charging wire to share images which I don't have right now.