Blue Spruce-always grafted?

Can someone please tell me why it seems that most, if not all, Blue Spruce trees are grafted? What is the advantage? I only see disadvantages. I would appreciate suggestions for a type of Blue Spruce that will do well in Zone 7, and stays around 40' or less at maturity. Skinny forms are fine!

The named selections are grafted to retain the qualities of the parent plant - great "blue" color of the needles typically, but sometimes it is habit, texture, density, dwarfness, etc. - while having a vigorous root system of the seedling understock.

I suppose one could root cuttings with some difficulty, and then have a poor growing but pure plant - but most people want something that grows well and looks good. So, you have grafted conifers.

What disadvantages do you perceive or have you experienced?

As far as what forms do well in zone 7, I'd say many could do fine provided you meet conditions that Picea pungens var. glauca likes. That would be circumneutral to slightly acid well drained soils and as cool an exposure as you might be able to provide.

A quick perusal of plant collection lists of arboreta or botanic gardens (even nurserymen) for your general area of VA would show what is growing that you could have success with. The US National Arboretum might be the "type specimen" for you.

http://www.usna.usda.gov/
http://www.usna.usda.gov/Gardens/collections/VirtualTours/GotelliVirtualTour.html

I think I saw at least a dozen different ones in that display.

The major disadvantage is that grafted specimens very commonly do not develop apical dominance well - they know they are branches, and go on growing as branches, instead of nicely straight up. They do eventually make it, but not before first developing a badly shaped lower trunk which stays with them for the rest of their lives. Who wants a nice neat, tidy conical tree with a zig-zag bottom two metres of trunk?

Resin

Oh! Thank you very much. I am comparing grafted evergreens with grafted roses to come up with disadvantages (this is all I know). I would think that the graft area is a weak spot, and vulnerable to freezes, etc. Also, would you need to keep pruning away growth from the "parent trunk?" Conditions in my yard? How about being shaded a bit by a huge, overgrown Silver Maple (probably planted in the 1950's as was the house...LOL I seem to have a layer of brown top soil (lo and behild!), but Virginia red clay underneath, and there are those doggone silver maple roots to contend with...it would get the hot afternoon sun but shade from the maple.

Typically, you won't ever get sprouting from the understock of a grafted conifer like a pine, spruce, or fir. A proper graft within this range of plants won't typically be a weak spot either, and cold is not an issue. In other words: everything about grafting that can be a drawback with roses is NOT applicable here.

I can't help you as much with commendations about your site. That's tough.

If your neighborhood is of that 1950s era, then there were likely conifers like Blue Spruce planted at or since that time nearby. Take a look at how they are performing. If there are any at all with some size to them, then you should likely have similar opportunity for success.