What kind of fertilizer can I give roses at the start of the year to make...
For roses, it is best to use a general, well-balanced fertilizer (e.g., 10-10-10). Nitrogen and magnesium are most important for vegetative (or leaf) growth. If your fertilizer of choice does not contain magnesium, you can broadcast and incorporate dolomitic limestone.
Make the first application during bud break in the spring. Apply fertilizer after there is 3-4" of new growth. You can fertilize every 4 to 6 weeks during the growing season, but stop fertilization in late summer (late August or early September) as the roses begin to go dormant.