Gardening with young children

I have two boys, almost 3 years old and 14 months.  We spend most of the day in the garden when weather permits.  Some tips I have to keep my little ones active participants in meaningful work.

1.  Always have a spot in the garden that is not planted for digging.
2. Keep different sizes of shovels and trowels in the garden for easy unplanned digging.
3.  Plant extra carrots and beets.  When they would like to pull and pick I help them to thin these veggies.

4. We sow many onion sets (for green onions) and radishes.  I don't mind where these are planted because they are harvested in about 30 days and rarely in the way of other plants.
5.  Save your own Sunflower seeds, preferably multi-headed, then you have plenty for the children to place where they would like.  It is wonderful to have surprise sunflowers in the garden. (I have done the same with regular flax seed).