That's easy, when you realise what the doors are doing and when.
You have to get the doors open in the sequence they are shut.
As you have to move the bushes towards the left you need the doors to open from the left.
In your picture you have doors 1 and 3 done. Doors numbered from left to right.
Since 1 is first you need to make the next door, 2, to open.
That would be the top bush, move it right one and back to the left one and it should open.
So you then move the 2nd from the top bush one right and back one left and away you go.