Osmocote Preplant provides the ultimate season long nutritional needs for trees, plants and shrubs.
It's what we professionals use when potting, it has a slow release system that provides what the plant needs for a whole season. Follow the dosage and in one hit the plant is right for the year.
When planting small shrubs in 3 litre pots mix 25g in with the back fill. As a guide 5 litre 40g, 10 litre 50g, 15 litre 60g, 25 litre 70g. Larger trees and specimen shrubs 40 litre 80g, 60 litre 90g, 90 litre 115g.
You can also use the feed for existing plantings each spring. 50g per square metre of plantings. If it's a tree in a lawn or hardened soil it is better to drill some holes for the feed to get where it's needed without feeding the lawn or weeds. For the average order of 20 large hedging plants or shrubs in say 15 litre pots 1 bag would be enough for the planting. So if you were doing 50 laurels 5 foot in 30 litre pots then you would need 4 bags to give them 80g each. It answers the question of what food will give my new plants to get them moving.

For the ultimate outcome use this in the hole with a dusting of micro funghi and a handful of pelleted chicken poo on the surface then water well and watch them grow!