Young trees, whether fruit bearing or ornamental, all need attentive care to help establish themselves in the soil and prepare for vigorous growth and a long productive life. Water is perhaps the most critical cultural requirement in this process. Soil conditions and fertilizer nutrients matter, but consistently applied water either by irrigation or natural rainfall is a necessity.
Water the new tree deeply at planting time until the soil is saturated. This is to support the roots and to collapse any air pockets in the soil that may inhibit good root contact with the soil and slow or prevent uptake of nutrients and moisture.
Create a watering moat several inches tall with excess soil that extends at least six inches beyond the edge of the root ball. Fill the moat once a week or twice a week on warm or arid conditions. Knock down the basin during the first winter so rain and snow do not pool around the trunk.
Mulch around the base of the new tree with an organic material such as compost, shredded bark, leaf mold, sawdust or cocoa bean hulls. Create a three to six inch thick blanket in a doughnut formation starting a few inches out from the trunk and extending a foot past the drip line of the tree canopy. Mulch will help prevent moisture loss to evaporation and keep competitive weeds at bay.