If any one is looking for outdoor art activities I can highly recommend the Wooland Trusts Nature Detectives. There are free art ideas and activities for children to do this summer. You don't have to be a member. When my GCs are old enough I will enrol them ( they have to be 5, I think).
I have used this resource for many years whilst working with young adults with learning difficulties it is aimed at children from 5 to 12. There are recipes, spotter sheets and colouring sheets and lots of good ideas to try out.
Large flowerbed - starting again