How to Grow Silk Floss Trees

Pink flower of the Silk floss tree


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In the United States, there is a small geographic area where the Silk floss tree (Ceiba speciosa) can thrive. People who live there are treated to a wonderfully weird and exotically beautiful shade tree that is also armed and dangerous.

This grand ornamental deciduous tree, native to Argentina and Brazil, is a showy specimen with some unusual traits that make it hard to mistake it for any other tree. With its bulging prickly trunk, exotic flowers, tall size, silky floss, and pear-sized seeds pod, the tree is unique.

It is not uncommon to see Ceiba speciosa used as a street tree in southern Florida or California, making quite an impression, but, unfortunately, also a fair bit of a mess. While stunning and eye-catching, the tree does end up leaving a good amount of waste after leaves, seeds, and floss are shed.

The silk floss tree begins as a young sapling with a small bulge in the trunk that slowly enlarges to appear bloated at the base and tapering to the crown. The tree can be as thick as seven feet in girth at the bulge. The immature trees will have green bark, which will eventually turn to gray as they age. This green coloration has the biological trait of allowing the tree to continue photosynthesis while defoliated. The trunk is densely covered with sharp prickles that defend the tree from climbing wildlife. These prickles are a hazard to humans and make maintenance a chore.

It is fair to say that this tree may seem a little weird and tough to upkeep. However, its unique characteristics make it an interesting specimen in the right landscape and it also sports gorgeous flowers. They have the quality and form of hibiscus reaching five to six inches wide, and the colors are remarkable, being bright pink with a white center. These dazzling flowers cover the canopy when in bloom and are a magnet for pollinators, especially hummingbirds.

It is a good choice for a landscape design if you are in need of an exciting and unique tree that is large in scale, fast-growing, and has definite ornamental appeal. You'll have to be prepared for the additional maintenance work and prickly appendages, though, and it won't be suited to the colder regions on the United States.

Botanical Name  Ceiba speciosa (formerly Chorisia speciosa)
Common Name  Silk Floss Tree
Plant Type   Deciduous Tree
Mature Size  50 feet
Sun Exposure  Full Sun
Soil Type  Adaptable, well-drained
Soil pH  Adaptable
Bloom Time  October-November
Flower Color  Pink
Hardiness Zones  9-11
Native Area   South America
Toxicity  Yes

Silk Floss Tree Care

Growing the C. speciosa is ultimately about designing the tree’s placement in the landscape.  It needs to account for the tree’s fast growth (18-24 inches a year while young) and imposing defense mechanisms that can impale pedestrians and cars alike.

When placing it near a structure, consider the tree’s size at maturity and the maintenance required. For example, setting a tree so that waste continuously falls into the gutters will mean they are more likely to get blocked quickly.

Another consideration for safety is making sure the silk floss tree is placed away from paths or roadways. It can be seen as an obstacle due to its thorns and surface roots. Silk trees make excellent street trees until someone backs their car into a thorny trunk, and a gash five inches long is caused curbside.   

There are cultivars available that do not have the prickles, but these lack the character and four-season interest that the unique bark provides. One nicely flowering cultivar that is missing prickles is C. speciosa’ Majestic Beauty.’

Light

The silk tree prefers full sun and will achieve maximum blooms when given six to eight hours of sun a day.

Soil

Clay, sand, and loam will give the tree an excellent medium to grow and thrive. Whatever type of soil the silk floss tree is planted in should be well-draining. Acidity is preferred, but it will tolerate an alkaline environment.

Water

Irrigating the tree is essential during establishment. 15 -20 gallons of water per week until roots are established is a reasonable rate. After, watering as needed is acceptable. The silk floss is drought-tolerant, but extended droughts will hamper flowering.

Temperature and Humidity

Silk floss trees are not cold hardy and will not live long in temperatures lower than 20o Fahrenheit for extended periods. It can survive in USDA zones 9b-11. 

Fertilizer

This tree needs no fertilization, though testing the soil to amend for pH may be beneficial.

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