Horstmann blue atlas cedars (cedrus atlantica 'horstmann') are a cultivar (hybrid) of blue atlas cedars. Horstmann blue atlas cedars are a slow-growing, semi-dwarf evergreen tree with needles ranging from icy blue to sky blue. Expect your Horstmann cedar to reach 8 to 10 feet tall with a spread of 5-6 feet in 10 years. Horstmann blue atlas cedars may continue to grow past the 10-year mark but slowly and should not exceed 15 feet tall. Horstmann blue atlas cedars require the same growing conditions as other blue atlas cedars.
Plant Horstmann blue atlas cedars in early to mid-fall or 4 to 6 weeks before the first frost date in your region.
Choose a location in full sun with well-drained soil. Horstmann blue atlas cedars will tolerate a wide range of soil types but prefer slightly acidic (pH between 4.0 and 6.0) soils. Northern gardeners should site this cedar where it has protection from the prevailing winter wind.
Spread 4 to 5 inches of compost on the planting site. Mix the compost into the top 12 inches of soil.
Dig a hole just wide and deep enough for the Horstmann blue atlas cedar's root ball.
Remove the Horstmann blue atlas cedar from its container. Loosen the dirt around the root ball.
Prune off broken or damaged roots making cuts 1 to 2 inches above the damaged area.
Place the Horstmann blue atlas cedar in the hole. Back-fill with the removed soil, tamping it firmly around the roots to eliminate air pockets.
Water your Horstmann blue atlas cedar well. 1 to 2 gallons of water is sufficient. Give the water 1/2 gallon at a time, wait until the water is completely absorbed before adding more water.
Spread 1 to 2 inches of mulch around the tree to conserve water and prevent weed growth. Pull the soil 2 to 3 inches away from the trunk of the tree to prevent damage to the trunk.