Should zinnias be fertilized as soon as they start growing or wait until they are blooming?
Fertilizing Zinnias Grown From Seeds
Certified GKH Gardening Expert
When the seedlings are about 4 inches tall, you can fertilize with a light application of a 5-10-5 fertilizer.
You can repeat a feeding in mid-season to help them keep growing.
Do not over fertilize, as excessive nitrogen will cause lots of green leaves and little or no flowering.