That should be enough thinning for any cultivar, especially Honeycrisp, which I don't find prone to bienniel bearing, at least here in southeast NY. Climate does make a difference and a shorter season can give a tree less time to store adequate reserves.

Down here I have difficulty getting annual production from some of my latest varieties like Goldrush and Fuji. If all else fails you can strip all the flowers off every other branch next time. Sometimes thinning apples doesn't solve the problem, even if it's done in a timely manner (within 14 days of petal fall).

Maskountain:

Agree with Harvestman's comments 100%. 8 inches should be plenty of spacing for any apple variety, depending, of course, on the size of the branches and the chronological age of the tree, neither of which you mention.

I don't grow Honeycrisp here since my climate is a little too hot in summer (would if I could), but have never heard it is particularly prone to biennial bearing. If you are going to thin, do so as soon as you can identify the best, fastest-growing apple in the cluster. The sooner you can get them off, the better for the apples and the tree itself, and if you are going to thin blossoms I would take them off as soon as the buds appear. That's a sure recipe for good return bloom.

Don Yellman, Great Falls, VA

Honeycrisp certainly alternate bears at my place. If you really want to conquer alternate bearing then start experimenting with lime sulfur and oil at full bloom. this is tricky. The idea is to spray when about 10 to 35 percent of the flowers have been pollinated. The more you experiment and write down your experiments and results for future reference (I recommend cloud computing so things aren't lost to a trashed harddrive, stolen computer, etc.) the better for you.
You need to thin the flowers as soon as possible and waiting until they can be thinned off by hand is too late. The tree thinks she has a big crop this year so she is going take next year off. That is why jelly and harvest are saying take them off in the flower stage, or in jelly's case when they are buds.
"strip all the flowers off every other branch next time" ...wow. Between the two of them I don't know who is the most extreme, but they both sound like they don't appreciate the fine art of hand thinning.
I am going to try lime sulfur thinning on peaches next year. In just a small way.

Geraldo, there is no fine art of hand thinning that applies even from season to season on the same variety let alone to various varieties. Hand thinning is not an exact science as far as response you can count on.

Your tactic of burning flowers isn't even used east of the Mississippi as far as I know. It is notoriously difficult to have any control going that route because of unpredictable cropping here. You have no idea what the fruit set is going to be just because you have lots of flowers.

Fortunately the home grower doesn't have to get maximum yeald and removing flowers from entire branches is a simple way to be assured of annual cropping. Some varieties can be thinned properly and on time and still maintain a biennial habit, at least where I grow apples.

I am surprised at your haughty tone Geraldo. Both Don and I have an awful lot of experience with fruit trees in areas with much less predictable weather and cropping than where you perform your "fine art"..

Harvestman:

Um, Geraldo does not have a haughty tone. You have to know your Geraldo. You would probably like him.

Don Yellman, Great Falls, VA

I was burning flowers off of trees in the 1960s. So was the whole apple industry, even the one in New York state. We used a product called Elgetol. It was banned and we have never really replaced it. Everyone is or has tried lime sulfer and/or ATS.
"I am surprised at your haughty tone Geraldo. Both Don and I have an awful lot of experience with fruit trees in areas with much less predictable weather and cropping than where you perform your "fine art".."
good gawd, man, I was just trying to make a little joke and provide some up to date info on what the industry is doing. Just because the big growers do it shouldn't preclude the home growers from trying. I don't know why you have to get all pissy.

Not that pissy, and I am a big Geraldo fan, but I give no one carte blanche when challenging my big apple ego.

I am not a commercial apple grower and have a great deal of respect for anyone who has gone that route. My business is making sure home growers get great fruit and if they don't, I'm out of business. Commercial growers can be out of business even if they're succesful fruit growers.

I have read articles about using Crockers fish oil to blossum thin apples organicly in the west. The information I get is that blossum thinning isn't so useful out east because of more unpredictable fruit set. As I understand it, when we get cool wet weather during and immediately following petal fall it can have a strong negative affect on fruit set. Of course cool weather also affects the efficacy of chemical thinning- but the other way, by reducing thinning.

As far as my suggestion of removing all blossums from branches when all else fails to create annual fruiting, it is based on personal experience with a Goldrush apple tree on my own property.

Even after removing all flowers on every other spur and coming back shortly after petal fall to hand thin thoroughly I couldn't break biennial bearing on this tree. It was as if the tree just sent out a signal that could only be stopped by going radical. I did and of course it worked.

Goldrush is considered an annual bearer and further south it behaves much differently than here in NY. Even here, the reason my tree gives me so much trouble is that it looses the sun from mid-afternoon on but even in full exposure Goldrush can be difficult here.

When reading Beach's Apples of NY it is interesting how many of the heirloom varieties were noted not only for being biennial, but even triennial, so obviously thinning on such a variety as this wouldn't work consistantly.

Most newer varieties are fairly reliable annual bearers or they wouldn't be released. One clear exception for me, even when grown in optimum conditions, is the Fortune apple which has actually been triennial on a couple of sites- one with full sun exposure. I'm hoping the trees will settle down when they mature. In the humid part of the country the growing season doesn't give fruit trees as much total energy to work with. It's like a solar battery loosing power on cloudy days.