How to grow and care for Dahlia flower

Fertilize Dahlias
Look for a fertilizer that is high in potassium (K) and phosphorus (P) but low in nitrogen (N). Potassium and phosphorus encourage bud growth and flowering. to prevent lush bushes with few blooms. Check your NPK (nitrogen-phosphorus-potassium) levels in your fertilizer before you buy. Expert growers recommend formulas like 5-10-10, 10-20-20 or even 0-0-10. Fertilizing dahlias just a couple of times can make a big difference to the flower crop. Add at planting and no more than once a month before flowering begins.

Mulching Dahlias
In very hot, dry areas you may want to mulch to help retain moisture, but in most areas we recommend skipping compost so the soil can stay warmer and the foliage can stay dry.