Hello. I have been waiting patiently since last October for my new perenial wildflower meadow to grow. It was planted with top quality mix and plants germinated and were growing this spring. I over-seeded white yarrow and Shasta Daisy a few weeks ago. Now I've seen advice to avoid planting Yarrow in wildflower mixes because of its invasive nature. Is this true and do I have any options to prevent yarrow taking over.