From what I was taught by the town horticulturist, the main trailer root is supposed to be above ground so it can breathe. "Trees are not carrots." is what he always screams at everyone.
http://www.parkeronline.org/do...
I spent probably close to $2500 on trees/shrubs in '07 as we had a new house & we'd lost one of our major trees (had a freak snowstorm on 10/19/05 & it snapped my mature ash tree in half, then spent the next year deciding on what to do with the back yard). In April 2008, the weather was drop-dead GORGEOUS. We're talking 60s & 70s for like 4 weeks. Then, one night it dropped down to -17 degs and killed EVERYTHING, plus we ended up having almost 2' of "mush" (not really snow, but not rain.. more .. mushy wet stuff.. great for moisture!) plop down the next day. Needless to say, the 4 cherry trees I put in (Northstar, Montmorency, Bing, & Rainier) plus the 5 crabapples (Sergeant Tina, Profusion, Indian Magic, Prairie Fire, & Radiant), all the shrubs in the front except for the spirea & smoketree.. everything exploded because the sap had been running for about 3 weeks. Lost also a Golden Rain tree & a Mimosa Silk tree that same spring because of the cold snap. It was devastating. Luckily I had my receipts for EVERYTHING & the nursery gave me credit for 100% I lost.
That's the problem with our area. We're not 100% out of the woods guaranteed until June 30th! I've actually seen snow in June (2004) here in the metro, and because I sit so damned high up compared to most of the city (Denver's at 5280', I sit at about 6100'), plus I'm on the far far eastern edge of the metro, so I don't get the protection that the "mountain shadow" gets. That's why it's so retarded of me to try & grow roses, but I manage! Never said I was smart...