I'm sorry you feel that way @ArraDreaming
I don't know if this helps, but I want you to know I don't think you are dumb or unintelligent.
Even if you were, what's the worst that could happen? Maybe they reject or think less of you, but what if they offer you more help and support if you're struggling with them?
It's okay to ask for help if you need it. Even if you think your cover is blown, they may keep their opinions to themselves anyway.
You also don't sound dumb if you have a wife and kids. It means you care about them and love them. You also must know how to look after them and the plants at the nursery.