Sprouting

During last weeks trip to the supermarket I found Dutch purple carrots! Anecdotaly (i.e. I can't find a reference and haven't tried all that much) the first orange carrots are said to come from the Netherlands in the 17th century. I was aware it was possible to buy purple carrots in the heirloom mix from the Diggers club (http://www.diggers.com.au/) but to have these things common enough to enter the supermarket?
The carrots are a rich purple on the outside and a creamy yellow on the inside. They're not as sweet as orange carrots and will make a nice turnip replacement I think.
Of interest is the purple stain the juice leaves on my fingers. I may juice a bunch and see if I can use them to dye thread.

So, having used them for some delicious soup, I'm attempting to sprout the carrots. I didn't do this as a child so I'm not sure I'm doing it right... They don't appear to be shrivling and the sweet potato next to them is sprouting so with luck I'll have purple carrot and sweet potato casserole in a few months.