Sessions was born in San Francisco, California, and educated in Oakland. At the age of six, she moved with her family to a farm next to Lake Merritt. She attended the University of California, Berkeley in 1881 with a degree in natural science. While attending a San Franciscobusiness school, at the request of a friend, she moved to San Diego in 1883 to work as an eighth grade teacher and vice principal at Russ School. She worked at the school for over a year before she left due to health problems.
Adult life
In San Diego, Sessions quickly moved on to her true interest, the cultivation of plants. In 1885, she purchased a nursery; within a few years she was the owner of a flower shop as well as growing fields and nurseries in Coronado, Pacific Beach, and Mission Hills. The Mission Hills Nursery, which she founded in 1910 and sold to her employees the Antonicelli brothers in 1926, is still in operation. In 1892 Sessions struck a deal with the City of San Diego to lease of land in Balboa Park as her growing fields. In return, she agreed to plant 100 trees a year in the mostly barren park, as well as 300 trees a year in other parts of San Diego. This arrangement left the park with an array of cypress, pine, oak, pepper trees and eucalyptus grown in her gardens from seeds imported from around the world; virtually all of the older trees still seen in the park were planted by her. Among many other plant introductions, she is credited with importing and popularizing the jacaranda, now very familiar in the city. She also collected, propagated, and introduced many California native plants to the horticulture trade and into gardens. In 1900, she took a trip to Baja California to find a palm tree not native in San Diego to be planted at the park. She would also later take a seven-month trip through Europe where she collected multiple plant varieties that she eventually helped plant in the park. Together with Alfred D. Robinson she co-founded the San Diego Floral Association in 1907; it is the oldest garden club in Southern California. The garden club was influential in teaching San Diegans how to grow ornamental and edible plants, at a time when most San Diego landscaping consisted of dirt and sagebrush. Sessions worked with architect Hazel Wood Waterman on the garden design for a group of houses built by San Diego socialite Alice Lee near Balboa Park.
Personal life
Sessions never married and lived to be 82, when she died in San Diego on March 24, 1940. She is interred in Mount Hope Cemetery.
A 2013 children's picture book, The Tree Lady: The True Story of How One Tree-Loving Woman Changed a City Forever, tells the story of Kate's life, education, and contribution to San Diego civic life.
