Mandrake cultivation :
To plant Mandrake seeds you have to position your hero on a swamp and place 3 times a devil's dozen of seeds (39 total) on the ground from his inventory.
After that when the hero leaves the cell the seeds will start growing immediately.
Mandrake matures in 5 nights.
Do not allow machinery or soldier’s boots trample the sprouted seed. Only heroes with no soldiers, zeppelins and demons will pass the cell without hurting your agricultural swamps.
An image of the mandrake that is ready to be harvested.
To collect mandrake, you must enter the cell with any unit (not listed in the exceptions mentioned above).
Harvesting mandrake after complete ripeness brings you 52 roots.
If they are harvested prematurely, you will collect only 39 pieces (the ones that have been planted).
You can either spend your mandrake on recruiting mages or potion preparing and scroll production, or you may keep it and replant.