Q.Can I use Palm tree fertilizer on my rosemary hedge?
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Certified GKH Gardening Expert
Rosemary doesn't typically need fertilizer. If you think it looks poorly and needs some pepping up you could give it fish emulsion at 1/2 strength or just an all purpose fertilizer.
The palm tree fertilizer has specific nutrients for palm tree care so I would't recommend using it. The article below mentions fertilizer for herbs in the last full paragraph.
https://www.gardeningknowhow.com/garden-how-to/gardening-by-zone/zone-9-10-11/zone-9-herb-plants.htm