Which chemicals are you talking about and what are you wanting to do or use in the vegetables? Depends on the chemical. I use the chemical fertilizers like almost every farmer uses. There are only certain chemicals non-farmers can buy. Farmers have a license to buy them. They have to take continuing ed. If you, as a non-farmer, can buy it you can use it. Otherwise you can't use most chemicals.I can't grow actual grass without fertilizer, weeders and grub control. All of those chemicals say don't use in food crops. What's the secret?