The "Growth Rate" is the percentage you can expect to grow when you are planting seeds and breaking the blocks you harvest. So with BLACK BRICK, the growth rate is 1.28 or 28%. This means that if you plant 10 seeds, harvest the trees, and break all those blocks, you will most likely end up with about 12.8 seeds.
The "Gem Yield" is about how many gems you can expect to get when you plant a seed and break all the blocks from that tree.
