Select a place in full sunlight to grow your sunflower house. You will need some space at least five square feet, larger if you prefer. Loosen the soil in a narrow line (about two-to-three inches) along the perimeter of your square and prepare the soil for planting by adding a little compost or fertilizer.
Help the kids plant Mammoth Sunflower seeds (the ones that grow at least six feet tall), spacing the seeds 10-to-12 inches apart along the prepared perimeter. Follow planting directions on the package. Leave a two-foot wide gap unplanted on one end of the house, which will become the doorway.
Once the Mammoth Sunflowers have sprouted, plant seeds for mid-size sunflowers between them. You also can add seeds for smaller flowers, such as brightly colored zinnias. All of these additional flowers will fill in the walls of the sunflower house.
When the large sunflowers reach a height of about five-to-six feet, its time to create the roof of your house. For this you will need several long pieces of twine or yarn to gently tie the tops of the sunflowers together overhead. Loop the twine around one flower just beneath the head and gently pull it toward the center of the house, attaching it beneath the head of the opposite sunflower. Do this until all of the tall sunflowers are attached at their tops, arching over the open space below, creating the roof.
You can add a blanket or large piece of cardboard for the floor of your sunflower house.
As a fun variation, once the sunflowers are a few inches tall, plant a few vegetable plants on the sunny side of houses perimeter. Radishes are fun, colorful and tasty. A few pole beans or pea pod plants can climb the sunflower stems for added interest.
In early fall, after the kids have had weeks of fun in their hide-a-way, help them harvest some sunflower seeds for tasting and feeding the birds.