My Fairy Garden kits include soil and seeds - all you need is water and a little patience. One thing worth noting is that the gardener in me will point out that since the depth of these sets tends to be shallow, there isn't a lot of room for root systems to develop, so the plants you grow will do so to varying results. Most last a few months (some longer, some shorter), but what I've found is that the kids don't really care what you grow, as long as you grow something. What's perfect is fast-growing grass seed - lawn repair seed is excellent for this. It sprouts and develops quickly, and you "give it a hair cut" about once a week and get the awesome smell of fresh-cut grass at home! I also like to use Miracle-Gro Moisture Control Potting Mix in ours.
Our new Bean Blossom set (sent to us for review) is a tiny watering can Fairy house that comes with just two seeds - but they're special! Labeled as "Magic" and "Peace," you grow these one at a time, and when they sprout, the first leaves will have the words on them! As the pole beans grow, a support within the watering can will guide them, keeping them straight and tall.
Playmonster's My Fairy Garden collection is available now at retailers such as Toys "R" Us (where we've bought quite a few accessories), along with Amazon and the official Playmonster web store. Highly-recommended for budding gardeners and fairy fans. Rock Father-approved!