Fertilizing newly planted trees
Newly planted could mean anything from starting a seedling in a nursery ,to planting a well feathered tree.
To me , my goal for each is similar.
To achieve optimal growth at each stage, not excessive.
Don’t want any deficiencies, nor excess.
Assuming other nutrients in balance.,nitrogen and water ( need both )is like the gas pedal for growth. I like to have a “medium level baseline “of nitrogen from organic and or time release sources, using water soluble forms to give them a “kick “ when needed.
I believe ,Spring flush is when a high nutrient Status is most needed.
I also think that first flush relies ,in large part to what has been stored inside the plant from the previous growing season, spring applications coming into play a little later.
What I want is… a good amount of shoot growth in the spring,dark green efficient leafs for the season., no late season growth that won’t properly harden off before cold.
High levels of organic / time release nitrogen, and a wet late summer can cause excessive late growth, and should be avoided. We can’t always control the water.
Lack of water ,late summer is usually what slows growth, allowing things to harden off, but can’t always be counted on.
One benefit of soluble nitrogen ( urea , nitrate , etc ) is they are quick acting then only available for a short time, this allows control of fertility over time.
Turning on and off growth,.
Since they are like a salt and short acting, splitting the application is often best.
We don’t want to stress young trees with too much salt. ( fertilizer ).
So split application and adequate irrigation is in order.
I usually stop soluble nitrogen application by July 1st.
Fall fertilizer …
I have been applying nitrogen in early fall for the last 3 years with good results.
I wait until the trees have absolutely decided to stop growth, and are just thinking about Turing color. Usually September here.
I have noticed a better spring flush since I started fall application.
No noticeable winter injuries from fall application.
I believe the trees store this nitrogen inside, to be used for spring growing.
I would speculate that temperate trees have adapted to recycle nutrients from the leafs that fall . In the autumn. That’s my theory,how late this occurs , if at all , I have no idea ? I assume absorption would be water and temperature dependent ?
I assume the soil ( root ) temperature is warmer in late October than it is in March or April here.? But dryer. I usually fertilize just before leaf fall.
I push my trees in such a manner, because I want nursery trees that will grow quickly. Hit the ground running when planted out. Also pushing them once planted ,to out grow the deer. Hopefully within 3yrs.?
I usually only use this high fertility treatment for young trees.
Just for quick establishment. Once firmly established, and out growing the deer, I rarely fertilize.
No peer reviewed references , just my observations of what’s working here.
A note about urea …
Surface application of urea with out water can result in very high losses to volatilization in a few days. … ie . It just evaporates into thin air !
Need water to get it into soil.