use the right planting techniques with proper digging, handling, staking, backfilling, amending, mulching, and initial watering
digging The planting hole for each tree should be three times the diameter of the rootball (e.g., ~30”-wide for a 5–gallon container) – centered on the planting location (regardless of slope) – and almost as deep as the root ball is high (e.g., ~10”-deep for a 5–gallon container), with a level bottom and scored sides: click here for diagrams and details.
handling To avoid damaging the roots – before, during, and after unpotting the tree – it should be handled only by its container and its rootball, not by its nursery stake and/or trunk: click here for diagrams and details.
staking After the tree is centered in the hole – and before backfilling – two field stakes should be driven into undisturbed soil on either side of the rootball (in a line perpendicular to the prevailing wind), then the trunk should be tied (~loosely) to both field stakes with pairs of flexible straps to maintain its ~vertical position before the nursery stake & ties are removed: click here for diagrams and details.
backfilling After securing the tree to its field stakes, backfill the planting hole with the crumbled excavated soil (without amendments and excluding large rocks & debris) up to the level of the top of the rootball, then form a level circular berm at the perimeter of the planting hole and thoroughly saturate all of the backfill in order to settle it properly: click here for diagrams and details.
amending Note that no amendments should be included in the backfill – only a few tree species need particular amendments spread on the surface of the backfill soil after planting (as needed) while most need none at any time: click here for a list of tree species soil amendments.
mulching Cover the backfill soil (and any surface amendments) with a 3”–4”-thick layer of shredded bark mulch, tapering down on the rootball to 0”-thick at the tree trunk (i.e., so that the mulch is not in contact with the bark, thereby preventing fungal diseases from moisture trapped against the tree): click here for diagrams and details.
initial watering On the day after planting – with a volume equaling the container volume (e.g., a 5–gallon container actually holds ~4 gallons) – water the new tree every single day for one week, every two days for two weeks, every three days for three weeks, and so on until reaching the species target interval for established watering (ranging from 8 to 14 days): click here for a list of species-specific established watering interval targets.