X Cupressocyparis Leylandii is a cypress shrub commonly known as Leyland Cypress. With its tall upright habit, Leylandii is most commonly planted for windbreaks, screening and hedging. Leylandii comes in two main cultivar groups Golden and Green and each with similar growth habits and requirements, save colouration. Your budget and planting design will dictate the density of placement and the plants required to achieve the look you desire. Plant at least a foot apart at a minimum even if building an "instant" hedge. Leyland Cypress are low maintenance during their life as well as in planting.
Dig a hole in rich well drained soil at least twice as wide and as deep as your Leylandii root ball. Loosen but do not remove the soil at the bottom of the hole to encourage the roots to spread.
Place the Leylandii plants in the hole, backfilling soil around the root ball and maintaining the established soil level around the main trunk. Water in well and add soil if there are any air pockets exposed with the watering in.
Monitor watering of your Leylandii while it is establishing itself. Do not let the roots dry out or allow them to sit in soaked soil. Keep surrounding soil evenly moist an inch down at all times. As Leylandii matures it becomes more drought tolerant but still does not appreciate dessicated soil.
Once established, fertilise the soil around your Leylandii once a year or less often as needed.