With Apple trees this is the time of the year that you want to get them prepared for going into dormancy not into a growing mode. Usually cut off any fertilizer in July only unless the trees are showing signs of no growth but typically July is the last application of fertilizer.
I myself think this is a myth,. The trees know what time of year it is. Many suggest fertilizing in the fall for trees such as Espoma company, but they do sell fertilizer! Again though you mention preparing for winter, in my mind, they need food for that. Once leaves start to turn, no way are they going to grow, so a good time to feed them. I have found weak plants do poorly over winter. Well fed ones do well.
I agree and so does Carl Whitcomb who has put it to the test through research. If rank growth stopped the tree from hardening off, then every time there was a drought in July and Aug and heavy rain first week of Sept trees would die like poisoned flies. What does happen in this case is that some growing tips get winter burn but the lower parts of trees seem to harden off fine.
I’ve been giving fruit trees Sept N. for years, but I have’t been scientific about it and do occasionally lose a tree to winter kill- however, Sept apps don’t ever create a surge in growth. The warm weather we have been having and lack of frost does and is.
Standard lawn maintenance calls for a high N app on labor day, BTW.
How about a low N, high P,K fertilizer? If it’s true that roots continue to grow during dormancy, wouldn’t a fertilizer high in P be beneficial in late fall?
Fall is the Prefered ( recommended ) time to apply. K. As the exchange sites in the soil that it binds to are emptier at that time. ( it can find a “parking spot”)
So the soil can be effectively recharged with K in the fall. This will be available to the plants in the spring
And no doubt ,perennials take some up?
Remember reading that walnuts take up significant K in the fall.
Phosphorus is a different story.
I believe fall application mostly either washes away. Or is fixated in the soil into unavailable forms. Which by spring may be unavailable .
Uptake in the fall ? Don’t know ?maybe ?
Nitrogen is ephemeral In the soil, there one ,day gone later, unless from slow release sources .I believe is taken up by plant very well before dormancy. And is the gas pedal of growth.and my main concern in this post.
Due to a reputation to lower hardyness, if applied late in the season.
The fate of these in the soil and in the plants in the "fall " are two different topics ,but should be discussed together .
There is a difference in efficient ,environmentally friendly use of fertilizer .
And pushing plants to their max with fertilizer.
All of these ,plus micronutrients ,etc …may be important to the optimum health of the plant going into winter
As to the comment about root "growth "continuing during dormancy.
I just don’t think roots do that much, at least not here.
But they do take up nutrients in the fall.
And maybe low N high PK would be good ?
I don’t know, a lot of this is pure speculation on my part.
I believe the concept that P is particularly a nutrient of import to roots is another long obsolete hort myth, although these things take a very, very long time to die- especially when such myths are useful for marketing. Research of its import to root growth used sterile soils, and even in that context was flawed, although I can’t remember the specifics of that. However, it turns out that N is the only nutrient that stimulates tree root growth in most soils. Vegetative and root growth actually go hand in hand, with the other variable being soil texture.
If a tree is deficient in any essential nutrient, it is a problem by definition, of course, but P deficiencies for trees are not common in soils with normal biological activity due to mychorizal relationships. Because of the time it takes for such relationships to develop, a P deficiency can be a problem in establishing vegetables in cool soils.
To address this you want a soluble P app at the same time in spring as you plant your starts or just as seedlings start to grow. Fall apps would be futile because P becomes fixed very quickly and then very slowly available.
The reason I do light N apps in mid-Sept is because I’m also applying K as Hillbilly suggests is common practice . I am hoping the N is drawn into spur leaves, which are last to drop in mid-Nov. I use an encapsulated 90 day to avoid run-off and also so I can use a spreader and not worry about burning lawns if rain is not in the immediate forecast. This also is a good time to apply a bit of N to turf anyway. If there was an available 60-day, I’d use that instead.
I’ve had many knowledgeable Nurserymen say the same thing as I have with regard to when it’s time to stop with fertilizer and it’s in the later parts of summer so, that’s what I go with. With what the trees need I’m thinking they have built up what’s needed for them to survive thru the dormancy season.
If it’s not broke, don’t fix it. Do what you think best.
Very good answer. I’d like not to have to fertilize my trees but it’s really not a practical idea to not give them the opportunity to use the valuable nutrition that it produces for my apple trees.
I grow peach trees and they need renewal from time to time. You have too keep on them, and they need food to keep up good production too. I’m happy with my regime. I just harvested 120 Indian Free peach on a tree that’s barely 5 feet tall. I gave half away. I will thin better in the future, although it was thinned OK. I just don’t need all those peaches. Size was big for the cultivar. Not known to be super productive, but mine seems to be.
With that much fruit on such a young and very small tree it sounds like your doing pretty good with caring for your peach trees. Keep up the great work.
I would like to clarify my interest here.( which may be different from yours ?)
I want to produce the highest quality nursery stock,mostly for my own use.
But also for future sales.
I want plants that in there fist year planted ,they grow like 3’ or so.
Some plants I have bought simply survive,…others thrive and grow like crazy the first year in the ground.
I attribute this to proper care and nutrition in the nursery.
I want a tree that will get over a deers head within 3 years of planting .
After they achieve this size and age they often require very little ,if any added fertilizer here.
By the time they reach Bering age , I often don’t add any fertilizer, but I am reevaluating this, due to differences in natural fertility.
When i said above about pushing trees to the max with fertilizer, I am meaning young nursery stalk, and/ or, newly planted trees.
Not trees of berring age, in fact I have found that once they get to berring age, you need to slow down vegetative growth to get fruit. ( depending on species )
I use a timed release fertilizer in my nursery stock. With good results.
Applied in the spring ,it often is used up by late summer.
Iam experimenting with a later application ( fall ) of a water soluble complete fertilizer…so far so good…
I try to time this to when the first cool night happen, and the leafs just start to turn.this seams late this year.
I do try to proved adiquate winter protection.
I am of the opinion that late fall application of fertilizer gets “into the plant,”
And is "in there "…"ready to go "In the spring ,when the soil is cold and absorption is slow of spring applied fertilizer.
We have similar goals as my nursery is an important part of my business and if a tree takes 3 years to be big enough to sell (2.5" caliber) instead of 4 or 4 instead of 5 it makes a huge difference in profit.