They do sell the rootstock at the time to plant.
I have no idea about the missing nutritional value. I just went looking and found this:
"Neither green nor white asparagus can be said to be superior to the other. Their organoleptic characteristics and culinary uses are different, but green asparagus does have greater nutritional value. The white surpasses the green only in total sugar content, so has more calories. Both types of asparagus have a high content of the anti-oxidizing vitamin A and C and of group B vitamins including folic acid. The high levels of potassium and calcium phosphate make asparagus particularly good for bone structure. The anthocyans, which are responsible for the purplish coloring of the green asparagus, protect the cardiovascular system. They increase in quantity as the colors become more intense, as does rutin which is known to provide protection against radiation and to assist in blood clotting. It is also a precursor of B complex vitamins. Saponins are responsible for the diuretic effects of asparagus and have a high fiber content. With respect to organoleptic characteristics, green asparagus has a more intense aroma than the white and its flavor is stronger and slightly sweet. Whereas white asparagus always needs to be peeled before cooking, the green does not. It has a fleshy texture and is firmer than the white after peeling.
Each type of asparagus has a different culinary use. The advantage of green asparagus is that it can be grilled rather than boiled, keeping in the flavor and aroma as well as conserving the vitamins and minerals, and this makes it more versatile. In general, asparagus can be eaten either hot or cold- with meat of fish, or in salads. It goes well with other vegetables or can be served alone or as the main ingredient of more sophisticated dishes."
Credit for the site:
http://www.donajuana.com/aspar...