Hi suzicatz, I use Potassium Permanganate, you can get it from Boots chemist in a 25g tub, or probably any chemist, Don't use it much now has I have Cichlids so only have floating plants, instructions how to use it in this link.....
http://www.aquajake.com/blog/planting ... g-plants-before-or-after/ It would be interesting to hear if anyone else still uses this method. Oh and welcome to the Forum
Chris