i think that is a great idea.
And a way around the 'card' issue, buy childrens birthday invites and send them out.
Put in the card " Seed party". Bring your own package of seeds as a birthday gift, and we will have a party planting them.
Spell it out like that. I wouldnt hesitate on that one bit.
Maybe, put a small hand written note inside the invite saying something along the lines of
-christmas just passed and mo got many things, but he really wants a garden. Seeds are the perfect gift and in line with the theme HE wants.. - ?
Activities for kids.. do you have a section of back yard that you dont mind sacrificing to some digging for the kids? That could be the activity.
Some plastic shovels, little buckets, and seeds. ( Grass seeds ifyou want that section of the yard to grow back at some point.
)
oh wait.....
its cold up there now isnt it?