On the second day, he planted 2 * 200 seedlings = <<2*200=400>>400 seedlings.
The total number of seedlings Remi planted on the two days is 400 seedlings + 200 seedlings = <<400+200=600>>600 seedlings.
If the total number of seedlings transferred from the nursery was 1200 after the second day, Remi's father planted 1200 seedlings - 600 seedlings = <<1200-600=600>>600 seedlings.
#### 600