One thing I learned well in this hobby, the hard way and much to my benefit, was not to trouble myself with species or individual trees that wouldn't grow well where I live, especially if there was not some REALLY good reason to bother. It's a matter of triage based on prognosis. You are capable of so much more in this hobby than this particular tree is ever likely to bring you. Save your energy and time and resources for really good material.
This is great advice. I've slowly learned this lesson myself. Some material is just not worth it, whether it's a particular species that doesn't do well in your climate or an individual tree that lacks the quality deserving of your time and attention. In my case, I found myself spending far more time that I should have on poor material, when the time could have been better spent working on my better trees.
Putting things in the ground is not a sure thing. I've got a bunch of small or crap stock that I put in the ground, and in some cases, they are developing nicely into material that I think will be good material to work on in the future, and in others, they are turning out so-so. The in-ground route does take a lot of time though - you're probably looking at a good 3 years to really begin seeing rapid growth for many species.