When and what to feed newly rooted gardenia cuttings.
Certified GKH Gardening Expert
You can give it some fertilizer now but I would only do so at half strength until they become more established. An acidic fertilizer is usually better. Miracle Gro is fine per directions on the package. Or, you can use a slow release fertilizer like Osmocote. This article will also help with fertlilizing your gardenia: https://www.gardeningknowhow.com/ornamental/flowers/gardenia/fertilizing-gardenias-in-your-garden.htm