Arborvitae Care and Feeding - Ask Extension
Is it worthwhile to fertilize arborvitae that are more than 60 years old?
Knowledgebase
Arborvitae Care and Feeding #873523
Asked June 17, 2024, 6:33 PM EDT
Is it worthwhile to fertilize arborvitae that are more than 60 years old?
Marion County Oregon
Expert Response
Dear Holt,
Thank you for contacting us about arborvitae. Any healthy tree is worth caring for. According to the University of Washington Botanic Gardens, arborvitae (Thuja occidentalis) can live to 50 to 150 years depending on the environmental conditions.
That being said, plants do not need fertilizer per se. They need nutrients which are normally supplied through healthy soil. So the goal we try to impart to gardeners is to build healthy soil.
Forests provide nutrients through the plants, leaves, wood, and other organic materials that fall to the ground and decompose. In a 'disturbed setting' such as developed housing sites, we are obliged to either replace the nutrients that are continuously being diminished, or we rely on fertilizer.
Very large (and old trees) are still growing foliage and roots. They require the macronutrients (nitrogen, phosphorus, and potassium) as well as more than a dozen micro nutrients. You can find fertilizers formulated for evergreen trees. When used exactly as directed (with respect to the amount, frequency, and method of application, these should provide most of what your trees need.
The other alternative is to build the soil through an annual application of about 1-inch of finished compost over the entire area (rootzone). Fallen leaves, grass cuttings, and other organic materials can all contribute to soil health.
I hope I haven't put you to sleep with my lengthy answer to your short question, but there are no simple answers when it comes to sustaining our natural resources. Please write again anytime you have questions.
Thank you for contacting us about arborvitae. Any healthy tree is worth caring for. According to the University of Washington Botanic Gardens, arborvitae (Thuja occidentalis) can live to 50 to 150 years depending on the environmental conditions.
That being said, plants do not need fertilizer per se. They need nutrients which are normally supplied through healthy soil. So the goal we try to impart to gardeners is to build healthy soil.
Forests provide nutrients through the plants, leaves, wood, and other organic materials that fall to the ground and decompose. In a 'disturbed setting' such as developed housing sites, we are obliged to either replace the nutrients that are continuously being diminished, or we rely on fertilizer.
Very large (and old trees) are still growing foliage and roots. They require the macronutrients (nitrogen, phosphorus, and potassium) as well as more than a dozen micro nutrients. You can find fertilizers formulated for evergreen trees. When used exactly as directed (with respect to the amount, frequency, and method of application, these should provide most of what your trees need.
The other alternative is to build the soil through an annual application of about 1-inch of finished compost over the entire area (rootzone). Fallen leaves, grass cuttings, and other organic materials can all contribute to soil health.
I hope I haven't put you to sleep with my lengthy answer to your short question, but there are no simple answers when it comes to sustaining our natural resources. Please write again anytime you have questions.
