Trees with Health Problems Change Color or Drop Leaves Too Early - Giroud Tree and Lawn Urges Homeowners to Be Alert for Fall Warning Signs of Sick Trees /ScoopCloud/ -- Tree service is needed for trees that change color too early or drop leaves prematurely. Most trees should be in full leaf and green through September; Giroud Tree and Lawn provides the top five Fall warning signs and actions Philadelphia homeowners can take to keep trees healthy and safe.