If you want to grow where there's local ditch weed or hemp remnants growing, you're going to get seeds, period.
How many seeds you get, you can decrease by going around and pulling all the males you can find within a mile or so of your house.
And remember that each morning when the dew falls, the pollen that was released the day before gets wet and non-viable.
Don't let the possibility of seeds discourage you too badly.