Portugese Laurel Hedge . . . thoughts and advice please

Firstly, many thanks to the contributors and their historic comments that I have read through helping me to gather knowledge and formulate a plan
I confess . . . I made an absolute cods of planting 20 x 5ft Portuguese Laurel to make an 'instant hedge' - am looking for 6ft or so in due course for privacy
So I received a load of rootball plants and shower the rootball lightly before planting next day. Plants went in too late (early spring) about 2 ft apart and I didn’t cut them back or nip them out and I didn’t give the rootball a soak prior to planting and the holes were only just about big enough to get the rootball in and the ground is well-compacted clay and I didn’t put a good mulch on top and I didn’t give them any Fish, Blood and Bone and they are sitting under trees so get robbed of water and light and I don’t water them as heavily or as often as I should . . . . probably. So, due to bad advice, some bad luck and a good dose of ignorance it is a proper comedy of errors. Having said/done that, about half of them have survived though have struggled a bit recently – too dry I think, top leaves going brown
Have now bitten the bullet and pulled up the dead ones and will replant the gaps. So here is my plan: dig a trench (in progress) a lot bigger than the pot and shove a load of part-composted kitchen waste peelings, tea bags, and grass cuttings in the bottom to retain moisture and a good sprinkle of Fish, Blood and Bone, then cover with compost. Tease out the roots of the new pot plants and put them in, fill up the gaps with a mix of the existing clay soil and compost. Put a layer of mulch on top – how much? The new plants have been growing happily in their pots this year and are currently 3-4ft – intend to cut back height and a third off any spindly branches. Thoughts on severity welcome bearing in mind I am after a 6ft wall of green as soon as possible. Water in well . . . and continue to water until the rains set in.
The survivors are about 5ft so I’ll cut them back also - guessing this is so they can throw their energy into developing a good root system? After watering, pile their bases (not touching the trunks) with mulch and a good sprinkle of Fish Blood and Bone and water regularly until the rainy season.
Also intend to cut back the tree branches overhead to allow more rain and light through. Thinking light is okay-ish as faces almost due South
While I am at it would it make sense to put in some form of irrigation pipe in the trench for new plants and on the surface for the survivors as well? (Would also make watering quicker for me – will be about 50m in all)
To aid the struggling survivors I had an idea about using a ¾” drill (14” long) to perforate the soil between footpath and the plant – hopefully not damaging their roots. Then sticking some of these moisture retaining crystals, down there with some Fish Blood and Bone – is this complete madness? Forking is close to impossible as the ground is that hard – soil is well-compacted clay
Compost thoughts? I have a pile of inherited compost (I think) been left about ten years and surrounded by ivy. Can I use this without any ivy taking over in the new location?
Could do with thoughts on what to do when – a planting / maintenance calendar
Am also interested to know how long I should expect to wait for a fully fledged 6ft hedge so I can manage expectations
Thanks if you made it this far. Anything I have missed? Guidance and best advice welcome
Posts
If the plants are not very bushy, you can give them a light trim now. You can give them another trim in late spring next year to keep them bushy and encourage further branching. Growth rate all depends on your local conditions, but it's very possible they will reach 5-6 ft in 2 years if all goes well.
There's a house near me which has a mature hedge along the [main] road boundary. When it was being sold [must be around ten years ago] the owners put in another one to give a bit of privacy to the back garden, as it's a corner site. They bought 5 or 6 foot ones. They still look pretty awful, as they've never been pruned, and basically still look much the same as they did when they were planted.
We have good conditions here for laurel, and the other hedge is really sturdy and dense. It proves the point that a good prune really benefits them
I live in west central Scotland - not where that photo is...
They'll be fine, they’ll get all the winter rain they need and will reward you next year.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.