I doubt you will find much difference (other than flowers) between the two. Mature size will be roughly similar although the 'Okame' may get there faster. Both are likely to be just as susceptible to the common flowering cherry pests and diseases - that is a characteristic that virtually all flowering cherries share, unfortunately :-)

Sounds like your nurseryman is just trying to push the plants he has on hand, a pretty common occurrence. I have no idea why he couldn't obtain an Okame of smaller size - it depends entirely on grower availability, so perhaps this late in the season only big trees remain available. In my area, flowering cherries and other spring blooming trees are ordered in fall for the following season so if they are not available at your local garden center now (or earlier, usually), you won't see them again until next spring.

Yes, Kansan can reach thirty-forty feet. I spent part of the day yesterday hanging from an upstairs window doing some limbing in one

Geez, I would have thought that if it were only a matter of availability he would tell me so can decide if I want to wait or not (which of course I don't LOL). But a 30 or 40 foot tree is too large for my space I think.

Do they sell these as dwarfs? And also what's the difference in the flower? Does one have more and abundance of flowers than the other?

'Kanzan' grows twice as big as 'Okame'. Here in Zone 8 'Kanzan' are known 50' tall. It is a big heavy double-flowered Sato cherry, whereas 'Okame' produces small single flowers much earlier in the season.

Thanks everyone. I don't need a tree that will grow that large. I'll either have to push the issue with my nursery or get it from somewhere else.

Another difference in this area is that 'Okame' is an awful disease magnet on most sites whereas 'Kanzan' is not. Hotter eastern climates may produce better results with 'Okame' than here.

@bboy

Which diseases exactly are Okame prone to? I never thought choosing a tree would be this difficult.

You will find some difference in ultimate size on the Kanzan, depending if it is grafted or grown on its own roots. Even if it does top out at 30 feet or less, its spread may be twenty. Grafted trees may top out smaller. However, caveat emptor...... they are not considered a long-lived tree. Expect its lifespan to typically be 15 to 25 years. I planted one where I wanted its effect, and it is in a area where normally I would not have considered it because of space. I pollard the tree. It's not something a typical homeowner wants to commit to.

Thanks Calliope. Would you say the same is true for the Okame? I would like a tree that has a nice lifespan.

As with other trees the spread of 'Kanzan' is determined by the conditions of the individual growing site. Specimens with other trees near them, windy exposures or other influences do not develop the same shapes as the same kinds on different sites. A 'Kanzan' in my region that was 50' tall was 41' across the same year, whereas another example 39' high had an average crown spread of 55'.

Of course bboy is right, so many things impact potential. I'm sorry redteddy, I am not familiar with Okame on a personal basis.

I saw 3 gallon 'Okame' cherry trees at TSC back in early spring. I think they were about $20. I'm not sure if all TSC's get their stock from the same nursery though, probably not.

For $20? LOL! Thanks, I'm going to check that out. I'm not sure exactly how much they are at my nursery but he sells his trees for about $130-$175 or something like that.

The cheap trees are younger trees, not specimen, that are sold at big box stores. A nursery has a shorter peak season in which to sell items to stay afloat, so they sell premium trees at premium prices. Big box stores have other merchandise, like clothing or home improvement and tools to sell throughout the year.