Assuming you have a pure horticultural oil and not an oil/sulfur mix, then all you really need to know is that dormant oils and growing-season oils are really exactly the same thing and have been for the better part of a century. If the label on your oil recommends a more concentrated spray for the dormant season and a less concentrated spray for the growing season then once the leaf buds on your roses have started to open, use only the growing season concentration.

Oil and sulfur mixtures are sometimes sold as dormant sprays. These can be very phytotoxic and the simplest thing is to not use them at all.

Thanks, Mike Rivers. Good info.

Thanks Allin. I'm very impressed. My extension agent just told me she doesn't use it on roses as it only affects spider mites and aphids. She taught me to go after aphids VERY early, in March in 6b where we live. If you catch them early, they aren't a problem the rest of the season. I don't have spider mites because I don't use other caustic sprays, so I may just sit back this year, and take the easy way out.

Why does it have to be boiled?

The lime sulfer spray is supposed to be a fungicide, is it not?

Aphids are usually found on new growth which would not have emerged when the dormant oil sprays are supposed to be applied, so I am not understanding how they can control aphids.

I think it is supposed to smother the eggs. If you deal with aphids very early, when they first emerge, they won't be much of a problem later.

how do you deal with aphids very early? by spraying this stuff on your roses in late winter/early spring?

I spray the first ones I see with Safer. March isn't too early in 6 b.