Can you grow plants in a plastic Trug?
Yes you can, and yes drill some drainage holes in the bottom. It’s useful to scatter some crocks (broken earthenware flower pot) over the holes to prevent them becoming clogged with soil) Carrots are inclined to favour a sandier soil than most veg. I grow tomatoes in plastic trugs (on wheels so that I can trundle them to follow the sun), and have just sown lettuce seeds, radishes, cress, Spring Onions (white Lisbon), courgettes, capsicums and chillies in plastic trugs. I have also grown runner beans and potatoes in plastic containers (you can buy specially designed large holders for these), and, of course, he could grow strawberries and herbs in sectioned containers. Don’t worry about the odd bit of soil – it doesn’t harm earthworms! When I was a kid, sweets were on ration and our big treat was to nick the odd carrot from the end of a row and give them a cursory wash in the local drinking fountain!