When first planting, watering should be carefully monitored. It will take a week before your plant learns to take water from the ground around it and until that time will only take water from the root ball, so be sure to water it generously.
Watering should be as follows:
Planted in Spring - water daily
Planted in Summer - water twice daily
Planted in Fall - water daily for 2-3 weeks
After this time you will decrease watering for the next 2 weeks until you reach your usual watering cycle for that area of your yard. If you are unsure of what the watering should be, consider the following factors:
Amount of light: little light will indicate less water is needed; lots of sunlight would indicate the opposite
Protection: a lot of protection will indicate less water is needed; less protection would indicate the opposite
Soil type: clay soil does not drain quickly so less water is needed; sandy soil does so more water is needed
Drainage: The slope of the yard and type of soil will determine drainage. You want good drainage for most plants, especially evergreens, but you need to test how quickly water drains in each basic location in the yard. The best way to test is, when digging the hole for planting, fill it with water. Note how long it takes the water to drain away. Quick drainage would indicate more water needed multiple times. Slow drainage would indicate less water.
Other plants in the same location: Plants will compete for water and nutrients from the same area so a balance will be needed depending on how much water each of the plants or trees prefers. For example, a hackberry tree pulls a lot of water and nutrients from the soil around it and can kill the plants growing below it unless a balance for both is made.