Safe to fertilize young apple trees this time of year?

Hello, I am trying to size up some apple trees that have been in the ground for 1-2 years.
I have already fertilized twice this year. I am in Zone 6a southeast michigan.
I have lots of 10-10-10 in the garage and would like to give them one more shot of fertilizer before winter.
Is it too late?

No expert but most of the reading I’ve done here recommends no more fertilizer past August so the newest wood has time to harden off. This may not apply to apples as they are generally fairly hardy.

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It is too late for your 10-10-10, but a late-summer broadcast of Sul-Po-Mag would be beneficial. For dosage use the lbs./ sq.ft. listed on the bag or box. For area envision a square that extends 1 ft. past the furthest branch tip on each side of the tree. For application I recommend a handheld spreader.

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For trees that have been receiving plenty of nutrients I would say that there is nothing to gain. For stressed trees and trees that you got to them late in the season (helping a friend’s tree) there is a modicum of benefit.

Right until bloom most trees rely on stored nutrients, most of the early feeding is intended for later when leaves can start doing their thing. If the tired tree still has leaves a foliar application would help it fill it’s stores.

9 times out of 10 you are better off just waiting for spring.


A small amount of fertilizer probably does no harm. But, October growth in zone 6 will die back if freezing weather arrives abruptly. I’ve had green leaves in December and no real harm…other years, a bunch of the tip dies. I fertilized lightly a couple weeks ago some of my potted trees.
Older trees…just do it in March or April…broadcast on the ground under the limbs.

Thanks for all the responses. I think I will leave the fertilizer alone.
I’ll keep watering though. It has been dry this year

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Hi Richard,
If I want to prepare new area for blueberries next year where I also plan to compost heavily overwinter, would Sul-Po-Mag, be preferred over just sulphur powder?
Kent, wa

No reason to apply any N this time of year for sure, can spur new growth that will not harden off properly before Winter. If by chance the tree doesnt pick up the N it will likely leach out of the root zone by Spring anyhow. N is very mobile in the soil profile.


Sul-Po-Mag is pH neutral until it starts dissolving, and what follows next usually doesn’t impact the media pH by much.

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I disagree with most of the comments above. At least now.
In the past I was taught to not fertilize after July , due to risk of winter injury.
However since about 2017 I have been experimenting with fall fertilization. Now I do this regularly on young,1yr-3yr old trees here in Wv.
With excellent results , no winter injury.
I think it’s important to not encourage late summer growth so that shoots harden for winter in a timely manner.
After shoots have hardened , and fall is upon us , when leafs show the slightest signs of fall color change .
I believe fall ( September, October, - November) nitrogen fertilization is of great benefit to young trees that you want to jump up growing in the comming spring. I have not seen Nitrogen stimulate any new fall growth when applied after September here.
The natural cycle is that leafs fall in the fall , release nutrients that the tree absorb in the fall to be stored inside the tree for spring growth. Recycling nutrients.
These stored nutrients in the tree tissue are the first available when growth starts in the spring. Before the soil warms enough for effective root absorption from spring application.
I have done trials on this , with / without fall application in my little nursery and field plantings.the results are dramatic.
With fall application of N the plants jump in the spring , first leafs look extremely dark green, fast healthy shoot growth.
Have not noticed any winter injuries from such practices.
So now , I am a big advocate of fall fertilization. !
Mostly , my goal is to get really fast growth / establishment of young trees so they become deer proof because of size.
Working for me ……


I don’t disagree with what you are saying but just like there is so much water a bucket can hold there is so much nitrogen a tree can hold. If the soil is fertile and the tree is healthy, it already absorbed what it can use.

Then there is the fact that too much of a good thing is not a good thing, plants can’t regulate the up take of nitrogen all that well. You got little to nothing to gain, but you can still damage the tree.


This is interesting. What kind of fertilizer do you use? I have about 100 pounds of 10-10-10 I want to use up.
Thanks for the info

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I would suggest you do a trial , one with / one with out.
Watch the results, which speak for themselves.
Then ….comment


Sources could vary depending what you have on hand,

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I wish it was that simple. I have two trees, same variety, next to each other, both treated the same way. One just happens to be a born over achiever.

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Fall fertilization is routine at orchards I be worked at, foliar urea application done prior to leaf drop helps break down that material and may help with scab in addition to growth benefits the following year


Most seasons you may get away with lots of late season growth.

There are at least two dangers in excessive fertilization; you can burn the plants if it turns dry and there’s no precipitation or irrigation, and in those seasons it goes from 40 to 15 degrees abruptly or even colder…and all that new growth dies and the tree is shorter rather than taller next summer.

But, I don’t blame you for experimenting. In zone 6 your’re probably not going to kill any trees by moderate fall fertilization.

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My thoughts on this topic which brought me searching for a thread like this one…

Leaf fall in fall, the energy goes into root growth and then winter dormancy.

If i fertilize just before or during leaf fall the root growth is encouraged to increase.

Bigger roots the next year. How much and what kind of fertilizer is unkown to me I am just rolling that idea around today.

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Very general…but you want less nitrogen in fall, and more other nutrients.

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I’ve researched this and have written in my notes for my USDA zone 6B. Fertilization is NOT recommended after July 15th. To allow ample time for tips to harden before freeze and reduce tip dieback over winter.

This may help some also.

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