How do I buy gardening spells? I need a spell card for pest 4. help, Please!
What kind of plant are you growing? The seeds that have a "rank only" thingy usually only have pests that can be killed by the pest spells that you have at that rank. When you level up with ranks, the higher ranked plants that you grow will have higher ranked pests, but these pests can usually be killed by the pest spells that you can get when you are at the rank in which you can purchase it.
Anyways ... since you said you have a rank 4 pest, you will need to travel to Mooshu and buy the spell "Pest Bomb" or "Fly Swatter" from the gardener in the Jade Palace for about 12500 gold, or 50000 for the "Fly Swatter". But since it takes about 24 hours or more for a post to appear, the plant you have that has the pest will probably be wilting or dead by the time you read this post.