Maple tree fertilizer - Ask Extension
What is the recommended N-P-K ratio for maple trees. We are thinking fertilizer spikes for feeding. There is one large silver maple that is 80 years o...
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Maple tree fertilizer #927129
Asked March 30, 2026, 10:02 PM EDT
What is the recommended N-P-K ratio for maple trees. We are thinking fertilizer spikes for feeding. There is one large silver maple that is 80 years old and 3 maples - autumn blaze and smaller maple species, that have been planted for about 5 years and are 4” caliper trees.
Denver County Colorado
Expert Response
Hi Todd,
The recommended N-P-K ratio for maple trees is 10-10-10 or 12-4-8. These ratios provide a balanced supply of nitrogen, phosphorus, and potassium, which are essential for the healthy growth of maple trees. It is important to note that while these ratios are commonly recommended, the specific needs of each tree may vary based on soil conditions and other factors. Therefore, it is advisable to conduct a soil test to determine the nutrient levels in the soil and adjust the fertilization accordingly.
Here is a link to CSU's soil testing laboratory:
Soil, Water and Plant Testing Laboratory - Soil Testing Lab
If you fertilize without a soil test, Extension guidance generally points toward a higher‑N, low‑P (and often low‑K) fertilizer rather than a “balanced” fertilizer—unless a soil test indicates P or K is needed.
Best timing to fertilize trees is noted in the Extension material as before leaf‑out or in the fall.
A brief sheet on fertilizing woody plants in Colorado:
http://planttalk.colostate.edu/topics/trees-shrubs-vines/1708-fertilizing-trees-shrubs/
Other related questions we receive about maples include questions on iron chlorosis (yellowing) in alkaline soils; a standard N‑P‑K fertilizer won’t correct that problem—this is a soil chemistry/iron availability issue, so a soil test (including pH) is strongly recommended.
See more on iron chlorosis here:
https://planttalk.colostate.edu/topics/weeds-cultural-problems/2121-iron-chlorosis-trees
The recommended N-P-K ratio for maple trees is 10-10-10 or 12-4-8. These ratios provide a balanced supply of nitrogen, phosphorus, and potassium, which are essential for the healthy growth of maple trees. It is important to note that while these ratios are commonly recommended, the specific needs of each tree may vary based on soil conditions and other factors. Therefore, it is advisable to conduct a soil test to determine the nutrient levels in the soil and adjust the fertilization accordingly.
Here is a link to CSU's soil testing laboratory:
Soil, Water and Plant Testing Laboratory - Soil Testing Lab
If you fertilize without a soil test, Extension guidance generally points toward a higher‑N, low‑P (and often low‑K) fertilizer rather than a “balanced” fertilizer—unless a soil test indicates P or K is needed.
Best timing to fertilize trees is noted in the Extension material as before leaf‑out or in the fall.
A brief sheet on fertilizing woody plants in Colorado:
http://planttalk.colostate.edu/topics/trees-shrubs-vines/1708-fertilizing-trees-shrubs/
Other related questions we receive about maples include questions on iron chlorosis (yellowing) in alkaline soils; a standard N‑P‑K fertilizer won’t correct that problem—this is a soil chemistry/iron availability issue, so a soil test (including pH) is strongly recommended.
See more on iron chlorosis here:
https://planttalk.colostate.edu/topics/weeds-cultural-problems/2121-iron-chlorosis-trees
