All fantastic suggestions everyone!! When Melissa, my daughter, was that age, we did these kind of things:
1) I had two container combos (Hybrid Tea Rose and all edible herbs). She knew that all the plants in those pots were safe to nibble.
2) Great importance and reminders that many plants were dangerous/ poisonous. Some we could eat, some we could touch and some were completely hands off. Even though she loved to take apart a bleeding heart flower, she was well aware to never stick it in her mouth.
3) Her container was usually a "Shade Combo". Reasons were, the display didn't change much through the growing season and she would always check on it. It was always there and she would recognize it immediately. Kids don't like it when their flower stops blooming and shade combos tend to look the same throughout the growing season. At that age we would buy plants in flower for her container combo.
4) Watering was fun. I have an old fashion hand pump on top my rain barrel which kids love to fill pails or watering cans to "water the plants" FYI you will need to water after they water.
5) Any time you need digging done that is a great job....but you will need to dig after they are finished digging
6) Looking for bugs, specifically: ladybugs and relocate them to eat aphids. I've bought a bag of live ladybugs and the kid loved it. She was more about the bug management than caring for the plants
7) Kids "pick" flowers and don't deadhead. Point out the blooms that they can remove the petals and throw in the air.
8) Expect plants to pop up everywhere. Peas in the flowerbeds, house plants, etc.
9) Seeding is fun, but don't expect more than one small row or one tray.
10) If you choose a special plant, select the planting spot that makes it very special. I have a little statue of an angel on her tummy reading a book. This is always a great place for a special annual flower....one that blooms continually.
11) plant up a treasure chest (cheap at the dollar store) and you can add jewels, miniature figurines etc.
12) make a "fairy" garden...doesn't need to be big and can be in a container
Melissa was probably one of the only 4 year old's that knew the difference between a pansy and petunia. She spent hours in the veggie garden eating peas and carrots on the spot. I never expected her to "help" with any gardening, only enjoyed her "playing" in the garden at that age. As she grew older, of course our gardening time changed as far as tasks and "jobs".
One of the most fun things to do is grow annual poppies. We have a game to guess the colour of the bloom before the bud opens. The petals come out like tissue paper and I even like that game.
If nothing else, the kids need to appreciate and identify harmful plants. Everything else is all play.
