Do you know what type of conifers? Generally you need to clear all grass and other plants around the planting area so allow them to get as much moisture and nutrients, then a mulch. Have you kept them watered and cleared the area around (I see a lot of people putting conifers in grass and inevitably they go brown as the grass takes all the water!).

also mid summer is possibly the worst time to plant your conifers . they should come round with plenty of water this year and next at least .