What is the secret to a beautiful scented rose, is it the quality of the soil ?

Can I replace shop bought soil with my own home-made compost soil ?

What is it that makes a rose smell beautiful ?

It might be your nose.
I am sure there are all kinds of possible reasons out there but the olefactory sense is very difficult to predict. It is NOT as simple as is it or isn't it fragrant.

I relay this story all the time, as an American Orchid Society judge years ago, I found myself judging fragrance as part of my teams duties. Every plant on the judging table was entered because it was fragrant.
12 people were on my team, like 7 people said it smells like a spring bouquet!! 2 people said it smelled like Pine Sol cleaner, one person said that the flower had a Spicy fragrance!! AND two judges said it had no fragrance at all!! None.

How can one explain that? It is simple, you can't explain it! Everyone's nose is different and not much is predictable!

That was under competitive conditions.

I mean street side flowers, growing in people's front gardens.

Some have a scent, and others just don't.

I wanted to know if it was the plant itself, or if the soil played a significant role ?

It's the plant itself, genetically coded. Overall plant health might lessen or intensify scent as does temperature and even time of day, but external conditions won't create scent where there is none. Many beautiful roses have no scent, sadly.

That's what I thought.

I can't believe they're bred without scent in mind. It's instinctive to draw in their nectar, it's the first thing anybody does when presented with flowers.

This thread is exactly on point for you!

https://garden.org/thread/go/1...

I actually already read that one, that was what got me on the issue, I couldn't believe it.

There have been mentions of potassium bringing more intense smell, and of course mentions of certain roses actually smelling only once the PH of the soil was changed (BTW roses expected to have a scent not those not knows to have no scent at all), so there is something with regards to the soil for certain roses.

Some garden roses don't appear to have a scent at a particular time of the day but will have one at a different time of the day.

People tend to call a rose scent a rose scent and generally label the scent as good or excellent based on it's intensity, but in practice some roses have an apple like scent without really feeling that is a rose , for example the rambler Paul Noel (1910), which I found very nice. Not all apple scented roses are identical to me, some can have a secondary scent that is somewhat a heightened piercing smell and takes away from the apple scent if sniffed profoundly,