Farming this herb is very easy as its In the starting areas for Northrend, Howling fjords is going to be the first place to go to for this herb as it has many more Nodes here than any other location in Northrend.
To be able to farm this then you will need a herbalism skill of 350 and a flying mount would be a huge advantage because if your just starting out in Northrend at level 68 then handling the mobs and be pretty tricky.
This herb is also used alot in leveling alchemy into Lich King level so you will be making a decent amout of gold from this route and the herbs should sell very well on the auction house.
We have put together a Good strong farming route for this herb for you guys
After sending our guys out to scout the best place to farm this herb Howling Fjords came back as number one by a long shot.
Take a look at the route below and have fun farming.