Plan for the 25'.

Notice the time frame given.

Here is a link that might be useful: Magnolia x loebneri 'Leonard Messel'

Thanks for the info.... very helpful. The tree is about 3 ft high now, so 25ft and 50 years is not a problem..... since I am now 74, I don't think I have to worry too much about size!

That was the top end of the time range. A young reasonably vigorous specimen should be growing something like 12" per year. As with other magnolias much faster growth is possible with a fertilization etc. regime chosen specifically to stimulate rapid growth; one year old seedlings of other kinds of magnolias have been produced that were the size and structure of sunflower plants.

The 'Leonard Messel' at the Seattle arboretum are maybe 12'-15' tall now after many years. I don't know when they were planted and how big they were, nor exactly how tall they are now. Maybe it says in Trees of Seattle - Second Edition. I am not where my copy is at the moment.

Wow! 12 ft a year, maybe I'll live long enough to see it a sizeable tree! What fertilizer regime do you suggest? It is in a sheltered, sunny corner, with low shrubs around it. The soil is awful (pure sand, like all my garden,) but I constantly try to improve it, and things seem to thrive there.

That was 12", not 12'. Try keeping it mulched with compost, wood chips etc.

I hit "submit" before I was done with that last one.

They also have it in the Soest Garden at CUH. I think there is more than one example there, if you look at some of the other lists you may find it is being grown on more than one soil in the display.

It seems to have come right along there.

Here is a link that might be useful: Bed #2 Partial Shade/Sandy Loam

The Gossler Farms web site said theirs was planted in 1975 and is now 25' tall.