Planting question for you experts

Compost ... did you use multi purpose? That tends to be quite dry/drying ... I wouldn't put it in a planting hole unless you're on heavy clay.

Yes, tease out the roots a bit when you plant out, and make sure you puddle them in well.

Where are you? What's your weather been like? (it's not the ideal time to be planting a hedge)

You say you added bonemeal and compost to the holes, but did you dig the ground over before making the holes?

Really and honestly the best way to plant a hedge is to dig trench and fully prepare the ground first, by digging quite deeply, breaking up the subsoil, and adding lots and lots of decent, rich, compost and/or rotted manure - not basic multi-purpose stuff which tends to only have a few months worth of nutrients.

Then it needs watering, lots and lots of water into the trench the day before the plants go anywhere near it, to make sure there's a good moist soil for them to grow into. The plants are going to be there for a very long time and need a good start if you're going to get a decent hedge.

When you take the plants out of their pots you need gently break some of the outside of the rootball, making sure some of the roots are pointing outwards and away from the main stem. It's especially important if they're potbound, you need to make sure the roots at the bottom of the pot are spread out a bit - don't worry if you break some, they'll grow new roots if they're happy. This makes them grow outwards into the surrounding soil instead or carrying on going round and round.

It's a good idea to plant with the main stems at an angle, it eventually makes a thicker hedge.

Backfill the trench and water again, and as you seem to be planting now, you'll need to carry on watering through to the autumn otherwise you could lose more plants. Mulch the plants with lawn mowings and leaves for as many years as you can get at the base, sprinkle blood fish and bone there too.

It's a lot of effort but is worth it in the long run. We've planted three complete hedges like this and never had a single loss - but it doesn't really help you, unless you're able to start again. You can dig the plants out, sort out the soil and replant them, as long as you don't leave them in the sun whilst they're out of the ground.

With individual holes - they should be at least double the size of the original pot, preferably much bigger, and should be at least double the depth too and prepared the same as the trench. You need to keep the plants watered, mulched and fed too.

Yeah. What he said.
If you want to do that - it sounds like a lot more than it is - then make sure the plants have had a bit of water a few hours before you take them out, wet the roots with a hose and then keep them covered while you dig the trench.
Of course you could try a variety of methods, but people would just accuse you of hedging your bets...