Patch Feature Help

In my mod, i am making a feature using a feature template for patches similar to pumpkin patches already in minecraft.

I want to make it so only 1-3 of the block will generate, but i don't know how the "number of tries", "XZ spread", and "Y spread" work, and how i'd make it only spawn 1-3 of the block.

I want to make some other features that are the same, but one of them generates 1-5 of the blocks, and another generates 1-10 of the blocks.

Here is an image of the feature:

Any help would be greatly appreicated!