Hi Kevin,
Most all weeping cherry trees are grafted onto other root stock these days (also called the stock root tree).* I suspect the sprouts are from the top part of the tree and the root stock has been damaged.* It can take a long time for the top to get some height, so you probably have a 5 year wait to see any height.* You might find these sites helpful to understand what I'm talking about.* This first site shows where the graft is made.
http://www.dogwooddesigner.com/?p=127
http://www.landscapingideasonline.co...herry-tree.php
Do you know which species of weeping cherry you purchased?* This site lists several.
http://landscaping.about.com/cs/tree...ping_trees.htm
This site shows how to prune one that is grafted and limbs have sprouted from the stock root tree.
http://www.freeplants.com/free-artic...erry-trees.htm
Newt
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.