Hey Tisha,
In answer to your question "will they eat dirt"...they'll eat anything!!! But look on the weed killer bag/jug, and it should tell you how long to keep pets/children off...Also, you
usually have to water it in, so,
for sure, if it says that, be sure it's totally watered (or rained on) before letting the puppy go on it...Now, be prepared for anything and everything to go into your puppy's mouth, in the backyard...I comb my yard
daily for strange things that seem to show up, and I have a 6' fence around it...
All the Best to you and your new little one, and the great love and adventure ahead of you...
Maggie & Apple
xoxox
xoxoxo