The Washington palm tree or Washingtonai robusta also is known as Mexican fan palm or Mexican Washington palm. This palm grows best in USDA hardiness zones 9 to 11 and can reach mature heights of more than 100 feet. This is the tropical palm tree often seen towering over boulevards or next to tall structures. Growing a Washington palm tree requires careful planning to ensure proper planting and plenty of room for its massive growth.
Find a location to plant the Washington palm tree that offers partial shade to full sun and well-draining soil. Stay clear of any areas with overhead obstructions, such as wires or other trees. Allocate enough room around the planting site for the palm's spread, which can be from 10 to 15 feet across.
Select a date for planting once the soil temperature is more than 65 degrees F. Clear the area of all foliage, rocks, branches and debris.
Dig a hole double the width of the Washington plam tree's container and the same depth. Plant the palm at the same level it was in the container. Remove the tree and place it in the hole. Backfill the hole around the tree with the removed soil.
Create a watering well around the planting hole, using the remaining soil and more, if needed. Mound the dirt to form a wall. Cover the area with 3 inches of mulch. Keep the mulch away from the trunk of the Washington palm tree.
Fill the water basin daily for 14 days and twice a week thereafter. Decrease the amount of water slowly over the first growing season. Never allow the soil to dry completely before watering.
Apply as directed a slow-release, special formulated fertilizer for palm trees. Spread it on the soil around the planting area, keeping it away from the trunk. Saturate the Washington palm tree thoroughly with water after fertilizing to ensure the fertilizer reaches the soil.