New street trees require little more than regular watering. The question is, how much and how often?
A newly planted tree will require 10 gallons of water every week. Take rainfall (or lack thereof) into consideration when planning your watering schedule. Sandy soil requires water more frequently than clay soils.
Be careful not to over water. Over-watering interferes with the roots ability to exchange oxygen. Check the soil. It should be moist not saturated. One test may be to take a handful of soil, close, then open your hand. If the soil retains its shape - but is not sticky, the moisture content is favorable.
Newly planted street trees are mulched at the time of planting. Mulch settles and breaks down over time, therefore, adding a little mulch each spring or fall is beneficial. Please remember that mulch should NOT be heaped next to the trunk of the tree. A small gap should be left between the trunk and the mulch.