Roses should not need fertilization unless they've exhibited poor growth in recent years (and if they are in the right growing conditions, such as full sun and well-drained soil, protected from deer browsing) and a laboratory soil test has shown that there is a nutrient deficiency in the soil. Unless there is a soil nutrient deficiency, adding fertilizer won't help the plants much except for perhaps the nitrogen component of the fertilizer formulation. Over-applying any nutrient can harm plants, and in the case of nitrogen, can cause plants to flower less abundantly, so use caution if you apply anything and follow product label directions for dosing.

If you do fertilize, a general-purpose formulation should be fine unless soil test results show that a particular nutrient needs to be supplemented. Even though there are countless fertilizer formulations on the market, some of which are labeled for use on flowers or even roses in particular, the precise formulation or N-P-K ratio used isn't that important. Organic types of fertilizer are slow-release (the ideal type to use for most plants) and are primarily broken down by soil microbe activity, and that only tends to ramp-up as the soil gets warmer, so it's a bit early to be applying any fertilizer just yet.

Miri

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