Babies can and should play in the grass to develop their sensations and get exposure at this age. The Journal of Allergy and Clinic Immunology suggests parents should encourage their children to spend more time outdoors in grass and dirt. Exposure to allergens and bacteria during a baby's first year might prevent allergies and even asthma-related wheezing as your child grows. While grass could be itchy and might cause a rash, getting used to it might help them develop stronger immunity. Ensure the grass doesn't have lots of fertilizer, weed killer, or chemicals on it before letting your child play on it. It would be best if you sat beside them when they're playing so they don't end up putting dirt or grass in their mouth.