Found this info on Dynamite Website:

Easy To Use

Dynamite Complete Plant Food is so easy to use that you’ll spend less time working in your garden and more time enjoying it.

The Dynamite controlled-release formula lasts up to 9 months so you only have to feed once per growing season. For new plants and transplants, sprinkle Dynamite into the hole near the roots and then backfill. For established plants, just sprinkle on top of the soil and gently work it in. Always water thoroughly. Each Dynamite product label provides an easy-to-follow chart that lists the suggested application amounts. It also lists the analysis of the formula including the Nitrogen, Phosphorus, Potassium content and the micro-nutrient content. There is no risk of over-feeding with Dynamite. The coating process is so controlled that you will not burn your plants even if you accidently overfeed. Dynamite works great on plants in the ground or in containers – indoors or out.

http://www.dynamiteplantfood.com/the-products-rev/

Dynamite Fertilizer is non-organic...

Since Dynamite lasts all season I'd apply after roses are leafed out...

New roses I'd stick with the liquid your already using..

Thanks a lot Jim. I tried to do a search for Dynamite information and missed it. This is very helpful! I'll apply it when they leaf out.