Open Garden Day with the Harris Co. Master Gardeners Open Garden Day at Weekley Center is a children's program organized and presented by the Harris County Master Gardeners Association. We are the volunteer arm of the Harris County A. & M. Extension Services. Activities: 1. Every child can plant a couple of small pots with calendula seeds. This flowering plant will add color to your home, porch or garden from September through winter (needs minimal frost protection if outdoors). It has other interesting characteristics that we will talk about 2. Veggie Bingo--every child wins a small prize and can vote on their favorite veggie/fruit. 3.