Hi Alyrics

This is posted on Dalia Barn's website:

"Bone Meal is recommended at planting time. Bone Meal builds strong tubers. Dahlias require low nitrogen fertilizers. We recommend fertilizers with a 5-10-10 ratio within 30 days of planting and again approximately 4 weeks later. Do Not overfeed your dahlias, doing so will promote weak stems, small blooms or tubers that rot or shrivel in storage."

Hope this helps.