Why would you want to grow dandelions? It's high in calcium and guinea pigs can't eat too much of it, nor too often.
You'd be better off growing wheatgrass for them.
Yes, I know it's safe to feed. However, it's very high in calcium. Unless your pigs are less than 6 months old, don't feed to them too often. See the calcium content in this chart. I would not feed 2 - 4 times a week as the chart suggested, maybe more like 2 - 4 times a month, and won't feed at all to guinea pigs who are prone to having bladder stones. https://www.guineapigcages.com/foru...vy-Nutrition-Charts-amp-Poisonous-Plants-List