To find out how many total plants Samantha can grow with 8 seed packets, we first need to figure out the rate of plants grown per seed packet.
Samantha grew 12 plants with 6 seed packets, so we can calculate the unit rate:
\[ \text{Unit rate} = \frac{\text{Total plants}}{\text{Total seed packets}} = \frac{12 \text{ plants}}{6 \text{ seed packets}} = 2 \text{ plants per seed packet} \]
Now that we know Samantha can grow 2 plants with each seed packet, we can use this unit rate to find out how many plants she can grow with 8 seed packets:
\[ \text{Total plants} = \text{Unit rate} \times \text{Number of seed packets} = 2 \text{ plants per seed packet} \times 8 \text{ seed packets} = 16 \text{ plants} \]
Therefore, with 8 seed packets, Samantha can grow a total of 16 plants in her backyard.