Once established, they are often overlooked when hot, dry weather has us dragging hoses to water flower and vegetable gardens to keep them alive. Make ongoing care of trees part of your gardening routine, especially during extremely hot dry weather. Established trees with larger root systems and drought tolerant trees need less frequent watering than moisture lovers and new plantings. Check the soil moisture and water established trees when the top few inches of soil are dry. Avoid deep tilling that can damage the surface roots and fine feeder roots used to absorb water and nutrients.