The answer to 'why is my sod invasive plants' is that weeds or other unwanted plants may have been introduced into the sod during the growing or harvesting process. This can lead to these invasive plants spreading and taking over your new lawn. Common symptoms include patches of weeds, uneven growth, and the sod failing to establish properly.
To solve this issue, you'll need to identify and remove the invasive plants, then take steps to encourage healthy grass growth. This may involve re-sodding, applying herbicides, or overseeding your lawn. If the problem persists, it's best to consult a professional landscaper who can properly diagnose and treat the issue.