Plant in full sun to light shade and give deep, infrequent watering. It is cold hardy down to at least 10°F and useful in USDA Zones 7 and above where it is drought tolerant once established in areas with a relatively high-water table, but otherwise will look best with occasional deep watering. It also tolerates heat and the smoggy conditions of our urban environments. A wonderfully beautiful large tree which is attractive in foliage or when bare when its sunlit glowing white trunks and limbs look like a large natural sculpture.

Our native sycamore is a riparian species, found along streams at elevations below 4,000 feet from Shasta County down into Baja California. The name for the genus comes from the Greek name 'platanos' used for the Old World sycamore that is also known as Oriental plane tree (Platanus orientalis) and the specific epithet is a reference to flowers being in racemes - these flowers occur in spherical clusters in late winter and spring and are interesting but not showy.

Platanus racemosa is an outstanding and beautiful natural looking tree in the garden, but the pollen and fuzz of the leaves is also somewhat irritating and some are outright allergic to it, so best not used close too close to the home or over an often used areas such as a patio. Because of the heavy leaf drop it is also difficult to garden under and the understory is best left natural or with only a few durable plants. As a riparian species is considered to be a phreatophyte (from the Greek words 'phreatic' meaning "well" or "spring" and 'phyton' meaning plant) and its roots will seek water sources, so it is also best planted a distance away from older sewer lines or other leaking water sources. The species is susceptible to the leaf blight called anthracnose that is caused by the fungus Gloeosporium plantani which cause several leaf and twig drop episodes in moist years in the spring, but rarely does permanent damage; this disease has been shown to have this association with this tree for as long as humans have known it, even found on plants in the fossil record.

There has been recent concern about hybridization of our native sycamore with the non-native London Plane Tree (Platanus x acerifolia) with suspicion that some seed grown nursery plants might actually be hybrids. Our plants are cutting grown from an ancient tree that existed prior to the London Plane Tree being planted in California. Locally it is known as the Sister Witness Tree and it grows along San Jose Creek in Downtown Goleta. It is listed as the National Champion on the California Big Tree Registry. This tree was large enough in the 1700s to be used as a marker for the corner of an original Spanish land grant. Another Santa Barbara tree that was long used as a landmark was one at the south end of Milpas Street that reportedly had lanterns hung from the branches to be use as a beacon the help guide ships into the port. 

This information about Platanus racemosa 'Witness Tree' displayed is based on research conducted in our horticultural library and from reliable online resources. We also will relate observations made about it as it grows in our nursery gardens and other gardens we have visited, as well how the crops have performed in containers in our nursery field. We will also incorporate comments that we receive from others and we welcome hearing from anyone with additional information, particularly if they can share any cultural information that would aid others in growing it.