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Silk Trees

The kapok or silk floss tree grows in many places

How to Prune a Silk Tree

Silk trees are also called mimosa trees or silky acacia. They are a favorite among gardeners because of their beautiful hot pink flowers and hardiness. They grow in full sun to light shade, can thrive in most soil types and even tolerate drought. The species grows to about 25 feet high. One negative of the silk tree is that the wood is weak and brittle, which causes it to break accidentally. Pruning silk trees will create a better shape and keep them healthy.

Clip all but one stem when the silk tree is young to force it to grow into a single-stem tree. Allow several stems to grow if you want a multi-trunk tree.

Pruning carefully, shape the silk tree so it has a flat top. Without pruning, it will look more like a shrub.

Cut off the previous season's growth each spring. Limit the buds on each stem to five or six to control how large and wide the tree will become.

Use the shears to cut dead limbs as soon as they appear. Find where dead limbs meet healthy branches and cut at the V-shaped joint.

Control the growth of new silk trees by pulling seedlings as soon as they appear, before they're ready to flower.

How to Prune Mimosa Trees

Decide whether you want the mimosa tree to be a single-stem or multi-trunk tree. If you want it to have a single, leader stem, clip any competing stems with pruning shears while the tree is young. For more than one trunk, allow the other stems to grow.

Prune the silk tree in the spring, if necessary. Cut last year's growth back so the stems only have five or six buds. This will control the growth and spread of the tree.

Remove dead limbs as you notice them to keep the tree healthy. The wood tends to be brittle and weak, causing accidental breakage. Follow the branches into the center of the tree and clip them off where they meet healthy ones at a V-shaped joint. If they are too thick to handle with shears, use a pruning saw.

Pull seedlings and small plants as soon as they are big enough to grasp by hand, but before they flower. Mimosa trees can be very intrusive, dropping seeds and causing hundreds of new seedlings.

Floss Flower Fast Facts


The most popular floss flowers are dressed in luminescent blues. White, purple, red, and pink are also available, as are bi-color varieties, which change color as they mature.


The most popular floss flowers are “dwarf” types between 6 and 12 inches tall, but some outdoor garden varieties can grow up to 30 inches. Fluffy tufts of tiny flowers bloom atop the plant's bushy, green foliage.


Floss flowers are called annuals, meaning that they die each year after producing flowers. Many container gardeners use the seeds harvested from their last floss flower to grow a new one every year.


Floss flowers originated in Central America, between southern Mexico and the northern reaches of South America. They have since spread to portions of every other continent but Antarctica.


Outside of their natural range, floss flowers usually become invasive weeds that damage native plant populations.

Fun Fact

A defensive chemical within the floss flower works to poison the reproductive systems of insects that nibble on its foliage.

How to Fertilize a Silk Floss Tree

Dilute your liquid organic fertilizer for your silk floss tree in a bucket or watering can as directed on the packaging. Liquid fertilizers like kelp emulsion or fish emulsion are good liquid organic fertilizers. Different manufacturers will have different dilution recommendations. Mix enough to thoroughly soak the base of your silk floss tree.

Pour the diluted liquid fertilizer around the base of your silk floss tree once a month.

Loosen the top 4 to 6 inches of soil under your silk floss tree with a shovel every two to three years.

Mix an inch or two of composted manure or worm casings with the soil under your silk floss tree.

Mix the loosened soil and composted manure and worm casings with the soil under your silk floss tree.

Water your silk floss tree thoroughly to encourage the nutrients to soak down through the soil.