I user miracle grow every two weeks. I use the spray end dispenser, and count 12 seconds on each rose with the Miracle grow spraying on the rose leaves of each plant. Still a bit warm, you will want to do that in the late afternoon, or very early morning, or the miracle grow can burn the foliage with the sun shining on the wet leaves.This really works well for me with so many roses. You don't have so many, so depending you may just want to measure out the miracle grow in a bucket of water and water your roses that way. Either way will work fine.
If you don't want to have to fertilize so often; get the time released oscomote fertilizer for veggies, 15-15-15. Work it into the soil around each of your roses and they will be fertilized every time you water for three months.
Alan
