Water new trees once a week, regularly, during the first season, with l0 gallons of water. More for large trees. Pour the water down the trunks so it goes into the root ball, not along the top of the ground. In addition, whenever the leaves droop down or it is very hot, water again and mist the tops with the hose. Do not fertilize the first year.
A rule can be used to quickly divide a board into equal parts. Lay the rule on the board with the start of the scale against one edge. Then angle the opposite end to a number that is easily divided by the number of parts you want. (If you want to divide a board into three equal parts you might use 9 and mark the board at 3 and 6.) Likewise, if you need four equal parts, angle the rule to numbers divisible by four, like 8, 12 or 16.