Unless they're production (nut, fruit, etc.) species, there's rarely any need to fertilize trees, and certainly, those that are in the area being serviced by the fertilizer jockeys from the 'turf care' outfit are probably getting all they need, and then some.

My guess is that your trees probably need nothing more than maintenance of a good, sizeable mulch circle.

If you feel you must fertilize, have a soil analysis done and choose an appropriate fertilizer based on those results.

Fertilization varies with soil. Soil varies, thus the soil test. A tree may or may not need to be fertilized, depending on soil, same as any other kind of plant.

Fall is the best time to fertilize hardy plants, spring next best.

Lucky,

They could benefit from organic fertlizer to maximize growth (not same as chemical fertilzer which is far worse).

Jennie -

All young trees need a good sized mulch like 5 feet across for at least 5 years. You want to mimic the forest floor for young trees. The soil in lawn is far far far from ideal for young trees. Thats why young trees barely grow with the grass up to the trunk. My bur oak with mulch and organic fertlizer like soybean meal grew about 26 inches so far this year. Another tree that I planted last year grew around 24 inches. I still haven't found any trees that put on that much growth like that in my neighbors yard. Very few keep good sized mulch around their trees. Apparently some think one foot wide mulch is good enough! The ones with wide mulch grew bigger and faster.

Another huge factor is PROPER PLANTING. I see far too many trees not being planted the right way. They will never grow fast that way even proper mulching or fertilizer won't help much.

All purpose fertilizer is not for the trees.
It's for the humans to pick up at big box retailers to get a sense that they are accomplishing something by using the product. May very old champion trees predate the commercial fertilizer industry so if that isn't proof enough get that soil tested.

If the tree's are growing well and have good color, they probably do not need anything. If your soil's are lacking, most likely nitrogen...but a soil analysis would tell what may/might be needed. Make sure that if a sample is sent in, it gives recommendations you understand or you have someone who can interpret the results.
There are A LOT of commercial tree nurseries across the USA that use a "general purpose fertilizer" to grow their trees...but it is a buisness for them. They do provide, on the average, excessive nutrients to get the plant to a saleable size quickly (the sooner it reaches marketable size, the sooner they get their money and hopefully profit back) .
This is not really what is needed in your landscape, but fertilizer is not evil (some will probably disagree:-)) ) when used properly. If your trees look good, enjoy them.......

By definition, if the nutrients used are excessive then there is a screw-up. Unneeded fertilizer components used on a large scale operation could really add up.

"By definition, if the nutrients used are excessive then there is a screw-up"

True, but by who's standards do you apply the fertilizer?? Is it based on soil AND tissue analysis??? Just because it is in the soil, does not mean it is in the plant There are a lot of testing lab.'s in the USA and the world. There is not a "standard" as to what the soil or tissue analysis should be for a given plant, only general standards overall(and those can be VERY broad when you compare them). In the P. North West, phosphorus is probably the largest nutrient used in excess....some have not figured out by changing the pH they make what is there available. It is not a perfect world and even in the plant world, everyone is still learning;-)............

By calling it "excessive" you are saying you have a basis for knowing more was used than was needed.

"By calling it "excessive" you are saying you have a basis for knowing more was used than was needed"

Yes and no! A lot of growers grow plants based on units of N per growing season (P,K and minors come into play also...but N drives the plant). They know "apply this much in a year and this is normally the result for a saleable plant of a given grade". I personally question it because of what was not known when a given growers standard was aquired or learned. Yes, plants can be grown of sufficient growth to meet grade without using the "units of N" or other excessive nutrients(but the "rule of thumb" is pretty close if you want to keep it simple, many do this)....it is just hard to teach drivers how to drive after many years of practice.
I am not saying it is right, just stating the reality of growing plants for a public who wants large plants for a small price. What a commercial operation applies does not always apply to the final home of their plants.But commercial growers do know a thing or two about growing plants, no one can take that away from them.
Keep it simple, if your plants look good to YOUR eyes, they might be pretty happy.........

Just look at all the posts in the tree forums where people have dead trees after using miracle gro etc. Maybe we can at least agree that there is a difference in the fertilizer in use at tree farms and tree stakes you get at the garden center. That's the only point I'm trying to make.