What level do you have to be on to get people to plow on Farmtown on Facebook

It is not a level issue. You have to have a certain amount of neighbors (I think it may be 10 but it has been a while). To find out for sure, you can go to the marketplace, click on one of the other players and select the hire to plow at your farm option. You will then see a dialogue box that will tell you exactly how many neighbors you need.