This is the case. Both sentences have the same meaning. Another example of this is

Give a mouse a cookie, and it will want more

is the same as

If you give a mouse a cookie, then it will want more

For the "John" example, This is the case. Both sentences have the same meaning. Another example of this is

Give a mouse a cookie, and it will want more

is the same as

If you give a mouse a cookie, then it will want more

however, the "garden" statement isn't causal(it doesnt suggest that one event will cause the other). that is the only difference. It reads correctly