Muggles' Guide to Harry Potter/Magic/Mandrake

Overview
The Mandrake is an unremarkable-looking tufty sort of plant that is purple and green in color. When dug up, its root has the shape of a human being.

Extended Description
Mandrake or Mandragora is a powerful restorative and is a vital component in restorative potions; as a result, it is necessary in Harry Potter and the Chamber of Secrets, where it is used to brew a potion that is used to restore those who have been attacked by the monster of the Chamber. The cry of the uprooted Mandrake will kill; Harry's class is repotting them on his first day back in year 2, but these are very young, almost infant mandrakes (their roots look like wrinkled and ugly babies), and their cry will only knock you out for a couple of hours.

Analysis
In Harry Potter and the Chamber of Secrets, a potion based on mandrakes is used to restore those attacked by the Monster of the Chamber. As in many other places in the series, it becomes apparent that the preparation of potions takes time. In this case, before the victims can be restored, so that they can identify the monster, we must wait for the mandrakes to become mature; conveniently, they do so immediately after Harry has vanquished the monster. In this case, the delay in their maturing is used to force Harry and Ron to come up with the solution to the puzzle of the nature and location of monster and the Chamber, with only extremely limited help from Hermione.

Mandrakes appear again in Harry Potter and the Deathly Hallows, where we see Neville and Professor Sprout carrying the potted plants up to the battlements during the preparations for the Battle at Hogwarts. Apparently, they will be cast down upon the attackers, and the cry of the exposed mandrake roots will incapacitate the attacking Death Eaters.

Questions

 * 1) In Harry Potter and the Chamber of Secrets, Mandrakes are seen to take the entire school year to reach maturity. They were, however, needed early in the year as a potion ingredient. Granted that there is an educational reason for growing them on the grounds, why would it not have been possible to buy mature mandrake roots from a supplier, say in Diagon Alley?

Greater Picture
In Harry Potter and the Chamber of Secrets, the author devised humorous descriptions of the maturation steps of the mandrake plants. The phases of plant maturity were analogous to the development of human children. First the plants were described as becoming "moody and secretive" confirming they had reached adolescence. Next the mandrakes started throwing loud parties indicating their teenage phase. Finally the mandrakes were known to be fully matured when they started moving into each others' pots.