@Moondog, Yes as they grow older your roses will have more fragrance. However there are other factors to consider: How do you fertilize them?. I've been reading a few days ago about types of manures of how they affect the strength of fragrance. Chicken manure improves overall scent production making roses
I copied parts of a thread at HMF under Ebb Tide:
https://www.helpmefind.com/ros...
discussion id:Discussion id : 84-216
<Yes, soil and fertilizer have a factor on the scent. A friend from alkaline clay sent me a bloom of her Munstead Wood (grafted on Dr.Huey) & fertilized with fish-emulsion. And it was intensely fragrant !! The rose park's Munstead Wood is medium scent. And my own-root Munstead Wood only has a light scent, since it's 1st year.
<Roses' scent become stronger in 2nd or 3rd year. My Tchaikosky and William Shakespeare 2000's scents were barely there in the 1st year. Then the scent becomes stronger, and fantastic as the bush gets older. Clay soil does help with scent. The rose park nearby (alkaline clay) has the best scent on many roses ... but Chicago Botanical Garden (alkaline loamy soil) has much less scent on the same roses.>
more of the same author:
Also chicken manure helps with strong scent. My friend with the best-scent ever on Munstead Wood: she raises her own chicken and fertilizes her roses with chicken manure plus fish-emulsion (for deep colors). My Pink Peace grafted has light scent for 2 years, until I used "Coop Poop" no-odor chicken manure with NPK 2-4-3, the soluble phosphorus and copper in chicken manure gave Pink Peace a good scent, but Pink Peace grafted CAN NEVER measure up to Pink-Peace as own-root.
Another person noted the same as I do: when the soil is alkaline, the fruity and myrrh scent is strong. But Grafted-on-Dr.-Huey secretes more acid, which lessen the fruity and myrrh scent. Which explains why many people, including me complain about Pink-Peace-grafted with weaker scent, but Pink Peace own-root smells wonderfully strong: fruit-loops and butter-cream frosting.
One year I dumped acid-fertilizer on Mary Magdalene and took away its fabulous myrrh scent. Plus it broke out in mildew !! After I scraped off the sulfur/acid, and watered with my pH 9 tap-water, I got the myrrh scent back.
In contrast, the Old Rose scent is stronger when the soil is more acidic, and as own-root matures, it produces more acid, thus the Old Rose scent is more noticeable in the 2nd and 3rd year. The Old Rose scent is strongest with acidic rain water, and folks in CA with alkaline-tap water don't notice much scent in Austin with old-rose scents. A friend in CA could not smell anything from The Dark Lady, but that was the best smelling rose at Chicago Botanical Garden after lots of acidic rain.>
Google "organic rose" and you'll see organic rose forum, where I posted info. on where to buy no-odor Coop-poop chicken manure, plus how to deal with blackspots. I have Heirloom as grafted on Dr. Huey and also grew Heirloom as own-root. The own-root was much healthier, but roots was too small to survive my zone 5a winter. The Heirloom grafted is only happy with fast-draining & loamy potting soil, and tend to blackspot in dense clay. For BS-prone roses like Heirloom or Double Delight (grafted-on-Dr.Huey), I need to dig down 2.5 feet for fast-drainage in acidic rain, plus supply slow-released lime to UP the pH, since Dr. Huey rootstock likes it alkaline.
My Jude as own-root was 100% healthy in fast-draining potting soil, plus frequent doses of sulfate of potash/gypsum, but B.S. when I neglected soluble fertilizer. Such wimpy roots need either super-loamy & neutral pH soil, or "spoon-fed" with potassium/calcium, which are essential for thicker leaves against fungal invasion.
Lavenderlace: you are right about sandy soil (less magnesium), thus less scent than heavy clay. Magnesium is what makes clay sticky, and it's the "glue" to hold on to the scent. Nearby CANTIGNY ROSE PARK (alkaline clay) has better scent than loamy CHICAGO BOTANICAL roses. Cantigny rose park used to be a horse stable so there's a thick accumulation of COMPOSTED horse manure over decades. Horse eat oats, and oats are high in Omega-3 fatty acids. I put horse manure in a bucket, it rained, and I saw grease floating on top !!
A friend with heavy clay in CA sent me some blooms for me to sniff. Her roses have the best scents ever !! My heavy clay with horse manure can't match the intensity of her scents ... she fertilizes her roses with chicken manure plus fish emulsion (high in Omega-3). Fatty acids (Omega-3) is needed to retain the scent. Cooks often fry spices in oil, to induce flavors in food. Factors in fragrance: humidity, trace elements in soil, amount of magnesium, and Omega-3 fatty acids. Another factor which lessen the scent is lime (calcium). There's lime (to deodorize) in fresh horse manure, and that decreased roses' scents. One time I put gypsum (calcium sulfate) and that completely took away the scent of Basyes Blueberry rose (was intensely fragrant BEFORE the gypsum application.)
Magnesium is the top factor in retaining scent, esp. the fruity scent. Magnesium UP the pH level, and the fruity scent is definitely stronger at higher pH (Mich in HMF noted this, same with me & that friend in CA). The Old rose scent is stronger at acidic pH (like rain water). The nutrients in oats are 173 mg Omega-3 and 3,781 mg of Omega-6, plus 82% phosphorus and 383 % manganese. If the horse are fed oats, then there's a high level of manganese and fatty acids.
The lime I refer to is the ADDED oyster lime by my local stable to take away the horses' urine odor in their stall. Lime is also added to bagged cow-manure to lessen the stench. That raises the pH, plus take away Old-Rose scents. I always get better scent on my roses via stinky chicken manure .. horse manure (with lime added) lessen the scent on certain roses, esp. the old-rose and clove scents.>>
Living in the countryside can give you ready access to resources many deep urbanites can find it difficult to get.
I do hope that this gives you an inkling how complex the whole aspect of fragrance is. I'm diving heads on with this for my upcoming next spring ( september down here). I really want to figure out how to enhance fragrance in my bushes. I have a very sandy soil that has an acidic ph between 5.5 and 6.
Kindly
Arturo