Planting in General
Planting should always be done in the best possible and most suitable soil. This ensures that the transition for the plant from being cared and nurtured in a pot, possibly in a very controlled environment and in optimal conditions by a professional grower, can transpire as seamlessly as possible into your garden.
How to plant?
Different plants have different needs. Selecting the right soil is the first step. Then dig a hole in the desired place that also matches the plants need for light and dampness. The hole should typically be at least twice as wide and deep as the root clump. Test the drainage by filling the hole with water, if the water does not flow away, the hole needs to be even deeper and some additional drainage should be provided by filling the bottom of the hole with gravel.
When you plant a plant that has been grown in a pot make sure that you first of all buy a good quality plant with a root system that has grown fully into the pot. Remove the plant without too much damage to the roots, break the plastic pot if there is a need for it. If the root growth has been vigorous and it has begun to circle the pot, gently tease the roots out and spread them around. Make sure that you do not break too many of the fine hair like roots.
Fill the hole with some of the soil and water. Then place the plant in the hole so that the roots can spread out and fill with more soil. Make sure that the plant will be planted in the right height; this can be achieved by holding the plant while the hole is filled, it is easiest with shrubs and trees - perennials might take offense. Very gently firm the soil, never stomp and water again. Young trees need support for approximately 2-4 years while they grow into the ground and all plants need watering when the weather is dry and before their roots reach damper depths.