Because our children are so young, we like to use the simplest kinds of hands-on lessons during our Family Home Evenings to teach them about the gospel of Jesus Christ. Since we have been putting together our family garden this week, we used that to talk about what it means to "grow up unto the Lord". (See Helaman 3:21)
Just as a plant needs certain things to grow healthy and strong, every person needs and can do specific things to grow in faith and righteousness.
Using scrap paper, I created a simple-looking flowers with my children's faces in the middle. I used a very thin dowel for the stem, but a chop stick or even a drinking straw would work just as well.
At the beginning of FHE, my kids planted themselves in "gospel sod" (our veggie garden) and we discussed the following scriptures which you might want to pick and choose from:
Lesson/Discussion Points: (Roughly based on this talk by Anne C. Pingree, May 2006 Ensign)
Making and keeping covenants with the Lord is like planting yourself in good soil
Keep Covenants: Doctrine and Covenants 35:24
Pray Always: 2 Nephi 32:9
Apply the Scriptures to Your Life: 1 Nephi 19:23
Repentening as often as we need to keeps weeds from weakening us unnecessarily
Keep the Commandments and Be Happy: Mosiah 2:22 and 41
Repent When Needed: D&C 19:16-17
Service and Following the Prophet will make us stronger and cause our roots to run deep
Service: Mosiah 2:17
Follow the Prophet's counsel:
After this brief discussion, we proceeded to do our regular planting...getting nice and dirty before bath/bedtime.
(Note: Obviously, you might not get to each of these points, but this might be a discussion for you to continue with your children whenever you have quiet moments out in the garden together...)