Straw your explanations are always so helpful and easy to understand! Thank you so much for sharing your experiences and learning with us!!!

Straw thank you so much for this! For most part I do have acidic loamy soil under my roses. ( I will still measure the pH more accurately than I have.) So, my problem is that why then am I getting less fragrance than certain flowers/bushes I know are capable of? I am getting fragrance but less than what I remember. Do you know other factors, Straw?

There are some roses specifically, that I want to know which pH range would give best fragrance. Just cant remember now, its so late. I definitely want to experiment with my potted roses!

Straw, do you have any guidance for what I could do regards pH (or any other factor if you think of it) for Kiss Me Kate and Laguna for fragrance? These are supposed to be super fragrant roses but I am not getting anything I can smell. Stacy, who lives in my region, says her KMK is very fragrant. So, I am thinking it might not be the weather.

Katy: I sniffed Laguna in a pot & partial shade at Meijers store, it was intensely spicy fragrant & also more blooms than leaves since the nursery used HIGH POTASSIUM & HIGH PHOSPHORUS slow-release blue granules in pot. Potting soil is wet and potassium is more available when the soil is wet.

Roses Unlimited uses a HIGH POTASSIUM & high phosphorus fertilizer plus vermiculite (holds moisture & potassium & nuttrients) and their roses ARE INTENSELY fragrant when I received them as gallon-size. Store sell a HUGE bag of vermicute for $16 .. it's worth putting in the planting hole to UP the moisture and holds more nutrients. But if your roses are ALREADY IN THE GROUND, any high potassium fertilizer would UP the scent, along with wetter soil. Cocoa mulch (high in potassium) UP the scents on all my roses, but that breed rose slugs so I stop using it.

I already tested high-phosphorus in the planting hole (composted cow manure) and THAT DID NOT UP the scent, so I'm pretty sure it's high potassium that UP the scent (tested that for the past decade).

I am going to add phosphorus ( fish bone meal), and potassium, langbeinite which is potassium magnesium sulfate to the roses tomorrow and see what happens. These two should increase the available phosphorus and potassium and then we will see!!! I will try it on Kiss Me Kate too. I had heard before too keeping the NPK values leaning towards high P and K was important for more flowering and fruiting...but had not heard anything about its effect on fragrance. I will give it a try for certain.

Thank you Straw!!!

Katy: Forget to tell you that the Laguna in the pot at local store was watered with alkaline tap-water at pH 9 (stated on our town's water-website). It was a hot & dry month when I saw Laguna in a pot. Their Laguna was grafted on Dr.Huey, and Dr.Huey rootstock produces plenty of acid to neutralize pH 9 tap water. Neutral to alkaline pH makes calcium & potassium & phosphorus & nitrogen MOST AVAILABLE.

That explains why my Pink Peace (grafted on Dr.Huey) has zero scent during acidic rain (pH 4.5 here), but my own-root Pink Peace has intense scent (its root produces less acid than big-fat Dr.Huey-rootstock). Many people complained that their Pink Peace (grafted on Dr.Huey) had zero scent, and other people (besides me) note that own-root smells better than grafted-on-Dr.Huey. Neutral to alkaline pH is the key to best scent. Joey in Wyoming, zone 4 with alkaline loamy sand & dry climate with rocks at bottom also noted that her roses are intensely fragrant. Higher pH produces a sweeter taste in fruits as well as sweeter scent in roses.

Carol (rosecanadian): Remember how I told you to top pots with a few pea gravel to UP the scent in rose? That was back in 2014 when I did that to Perle d" Or in a pot with one bloom perfumed the entire area. This year 2020 I was annoyed that leaves wilt in roses that receive the most rain, so I dug down to 4 to 6 inches and put a circular ring of pea gravel around roses that like it alkaline: Golden Celebration, Pat Austin, Evelyn. My roses are buried DEEP for zone 5 winter survival. NO MORE WILTING leaves even at 95 F heat, plus the scent is intensified DESPITE HEAVY RAIN. We had heavy rain recently that filled all my 6 rain-barrels, and right now I have a vase of Golden Celebration & Evelyn, W.S. 2000, and Savannah all intensely scented. Savannah is right next to the rain spout getting tons of acidic rain, but I put a pile of pea-gravel by the rain spout to neutralize its acidic rain (pH 4.5 here).

Ph affects how easily various things are absorbed into the plant. Fragrance being oils and chemical reactions would be affected by what the plant absorbs on some level.

Another aspect to consider is everyone smells differently. I can smell that usual mid strength fruity smell in alot of yellows and orange flower types but partner can't. I can't smell clove in any rose, Ebb Tide is lemony to me, most Rugosa have no smell to me but apparently are strong clove to others. I can smell clove in gladioli liliaceous and find it borderline offensive rather than pleasant.

I have no idea what my soil PH is ; my tiny apartment garden here is literally a mixed bag of dirt , raised up a foot with all kinds of organic bagged soil from the hardware store. It does have some nice worm activity . I throw organic vegetablest, coffee and Tea in , which possibly is conducive to the rose perfume from Strawberry Hill and Sidonie , it has been amazing this year now that the roses are two years old .

It seems to me , age of the rose has a lot to do with the scent on some varieties.

OK Straw:

a) since my soil is on the acidic side, say 6.5 ish

b) my tap water is acidic, 5.5 and this is what I use to water my entire garden

c) I have many OGRs with deep old rose scent

d) now I have acquired many modern roses, David Austin, Delbard, Kordes with other scent
genes, including old rose

e) my roses are own root, and grafted on drhuey, multiflora

f) all my roses are in ground. Some are temporarily potted before planting by end of fall.

so what do I do? with so many types of roots and scent genes? particularly since I want to accent both the old rose scent and the fruity scent and scent in general?

Spread a little lime and/or azomite at the base of the roses and with every watering a little bit of alkalinity will seep down? If the pH stays very close to 7 +/- will I still get the old rose scent and the fruity scent? or does the soil have to be more on the acidic side or alkaline side for either fragrance? You are right about that: adding a little lime to soil helps with sweetness of fruits, maybe some lime will work for scent of roses

I *think* between pH 6.5 to 7.5 the absorption of potassium will not become a issue.

I dont know where to start. I think I am just going to start with a high potassium fertilizer for now. By and by I will work on the pH.

Any comment you have, I value your greatly, is so appreciated!

berrypie: I hear that often, scent improves with age, particularly after the first three years and that makes sense to me. I am thinking of roses that have been in my garden a good while and seem not to emit as much scent this year as I remember from previous years. Strawberry Hill is a new rose for me this spring and I love the scent. For most part I did not worry about pH etc. My soil seemed very 'healthy' and things just grew well. Now I am getting into it and things are getting a little complicated.

This thread is fascinating. I’m in alkaline clay, hot dry CA. I use fish emulsion and coffee grounds on my roses, the latter especially because I read on this forum about the acidity-scent connection,

This year I bought Lavender Crush and Memorial Day for their fragrance, but get only a little scent from the first, and a kind of tepid, medium scent from the second. On the other hand, Princess Alexandra of Kent, planted in February, puts out multiple heavily scented blooms.

I had Oklahoma when I lived in 10a, and now that you mention it, it did smell like lychee fruit. I loved it whatever it was!

I wonder what else I might add to my soil to, as strawchicago puts it, UP the fragrance.

Sylvia: Lavender Crush's scent is strong in Walmart's pot (late fall with rain), and strong in my always-wet alkaline clay (fertilized with chicken manure which is high in boron, zinc, and copper ... these trace elements are added to chicken-feed). Potassium is MOST AVAILABLE when soil is wet, so hot & dry weather would lessen scent. Among my 130 fragrant own-root roses, the lavender & purple roses' scent are best with tons of acidic rain, but ABSENT during hot & dry.

Berrypie: Agree .. it took 2 years before the scent of Christopher Marlowe become strong. In its 1st year, I was disappointed in its mild scent, now Christopher Marlowe is 10th-year own root, and I love its strong scent.

Katy: If you google potassium co-factor, you'll see magnesium. Potassium works best when there's magnesium. Magnesium is what makes clay soil sticky. Magnesium makes soil dense thus retains nutrients. My clay is tested exceedingly high in magnesium at pH 7.7, and nearby Cantigny rose park is also alkaline clay (softer & fluffier than mine). The roses at Cantigny park are SUPER-FRAGRANT .. even the "mild" scent Lilian Austin is very strong. But the SAME ROSES have zero scent at Chicago Botanical Garden which is ALKALINE LOAMY & less sticky magnesium to hold potassium & trace elements. LEACHING is a big problem with loamy soil. I detected ZERO SCENT at CBG's old garden roses, and even their Gertrude Jekyll & Eglantyne have zero scent after week-long rain.

However, my Eglantyne and Lilian Austin as own-roots can't compare to the heavenly scent at Cantigny. Why? Potassium is most available when soil is WET with some magnesium for density, such as potting soil (peatmoss is actually dense, rather than fast-draining like sand). I had to use a steel scoop to scoop up MG-potting soil, so it has magnesium. Pots are well-fertilized with NPK 20-20-20 plus trace elements. My clay is very high in magnesium to the point of rock-hard, thus limit potassium mobility, but the scents improve when I make my soil fluffy.

Magnesium is in sticky & dense organic matter such as alfalfa meal, any leaves, also high in rocks and pea-gravel, and Azomite. I tested Azomite for cut blooms, and Azomite stuck tight to the bottom of the vase .. I had to scrub it with a brush. My high magnesium clay sticks tight to my skin. Soap and water won't take it off, I have to scrub my skin with alcohol to get the clay off. That's why topping with leaves, dolomitic lime (has both calcium and magnesiium), pea-gravel or Azomite helps to retain scent plus UP the pH of acidic rain.

Straw - You told me to make my soil more alkaline...so I did. I didn't use pea gravel...but I used lime. My roses have lots of fragrance now!! Mmmmm!! Thank you so much!! You are a genius!!! I should have used it during June and early July when we had so much rain. But better sooner rather than later. Interesting...so the alfalfa pellets I gave to my roses has Mg in it. So that helps with the fragrance.

Katya - I so agree with you...it seems very complicated to me. Thank goodness that Straw is such a help! :)

I think I know what I'm doing now. (Thank you Straw...I mean that from the bottom of my heart) My roses have so much fragrance. My most fragrant roses are Memorial Day, Parade Day, Scept'rd Isle, White Licorice and Augusta Luise. I have many more really fragrant roses...but these ones are always strongly fragrant (now).

Carol: THANK YOU for your kind words of support. I'm an experimenter, and NOT a theory-person. My B.S. degree is in Computer Science & minor in Chemistry & worked as a C-programmer, so I don't approach things through theories, I TEST IT, and report the results.

My goal is to save others from making the same mistakes I did through countless foolish experiments just to understand how things work. One of the WORST experiment I did was to plant a few roses in high-phosphorus composted cow manure. That was bad, did not increase the scent but roses came down with black spots. I should had known better back in 2013 when I topped Frederic Mistral with a bag of composted cow manure .. he went from being 100% healthy to black spot fest. High phosphorus makes calcium & potassium less available (both are essential for thicker leaves & fight against fungal invasion).

Leaves have plenty of magnesium. University of IL. reported that leaves decompose to ALKALINE. So I tested that: I stuffed a bunch of composted leaves (1-year-old) into FLUFFY & FAST-DRAINING & loamy soil. Few months later I dug that up and it turned into rock-hard-clay. In another bed, I dumped at least 100 bags of leaves through the years, and the top became dense & hard rather than fluffy. Leaves are fantastic for moisture retention with its density, same with clay. Topping with leaves definitely UP the scents in my roses since it retains moisture & nutrients & pH is alkaline when fully decomposed.

Uh, oh! Looks like I'm doing something else wrong. High phosphorous makes calcium less available? I'm using a MiracleGro with high phosphorous levels. Do you think a 20-20-20 would be better? Thanks!

Carol: You mean MG bloom-booster flower-food with NPK 15-30-15? I tested that in pots and was NOT impressed. If your roses bloom great, then NPK 20-20-20 plus more trace elements would be better. High phosphorus is needed only on stingy roses that won't bloom. High phosphorus helps with branching (more branches & more one-bloom per stem). High potassium also helps with blooming (but in cluster). But high phosphorus makes ugly plants with scorched leaves or black spotted leaves due to THINNER leaves, plus more pest-invasion. I got the WORST thrips on W.S. 2000 when I tested Dr.Earth high-phosphorus Flower-power. The roses with high phosphorus composted-cow-manure in the planting hole either have thrips, rose-slugs, or leaves get scorched & brown. Phosphorus burns, I should had known better when I tested bone-meal in 2001 on a bunch of geraniums. The flowers became vivid-colors, but leaves got scorched & brown.

Okay, that makes sense...I've never had leaves so affected with aphids. I'm going to the greenhouse to get pots for my streptocarpus plants that are coming. I'll get some 20-20-20 fertilizer. Thanks! :) :)

Carol: aphids like high nitrogen-fertilizer. Nitrogen induces fast growth & softer growth. Phosphorus makes leaves thinner. I would look for a formula with high potassium & calcium. Phosphorus, calcium and potassium all compete for absorption. At least nitrogen leaches out easily in pots (nitrogen mobility is a 10, potassium is a 3, and phosphorus is a 1). Phosphorus doesn't leach out much, and it can accumulate in pots or thick clay. For the past years I have zero aphids in my roses since I use SLOW-RELEASED nitrogen (blood meal at NPK 12-0-0, or feather meal), rather than fast release nitrogen which induces soft growth & inviting aphids to feast on.

Hmmmm....this is so complicated. :) :) So, high in K and lower in N and P. I'll try to find something like that. Thanks! :)

Carol: Remember Khalid who posted in Organic rose forum. He grew roses in 100+ pots in hot climate up to 112 F. His approach is same as mine: high potassium and high calcium, after I informed him of the ratio for roses (equal nitrogen to potassium, 1/2 calcium, and 1/10 phosphorus) ... that's from rose-tissue analysis by University of CA at Davis. Khalid is the leader of Facebook Fragrant Rose forum with 1,600 international members.

Wow! Go Khalid!! :) I tried to find you on what I think was the right forum...but I couldn't, so I gave up. LOL I bought some new Miracle Gro fertilizer today...phosphorous was lower than N and K. Thanks so much!! Should I add more bone meal for calcium?? :) Thanks!

Carol: Bone meal has both calcium & phosphorus, plus many trace elements. As you can see in the below link, chemical analysis of bone meal showed measurement in ppm (1 milligram per kilogram soil (mg/kg) )

400 iron, 120 magnesium, 50 manganese, 300 sodium, 200 aluminum, 2,000 sulfates, 20 potassium, 100 zinc, and 400 chlorides.

The biggest portions are 23% calcium and 14% phosphorus ... both essential for root growth. Phosphorus mobility is a 1, compared to 10 for nitrogen. Thus phosphorus via bone meal is best in the planting hole, rather than on top. Studies showed that phosphorus applied on top, only move down 1 inches per year.

Drawback of bone meal? It can only be utilized when the pH is below 7 (acidic). I already burnt plenty of plants when I tested bone meal in my pH 7.7 soil .... didn't work on top, nor in the planting hole.

Here is a link that might be useful: Ingredients in bone meal

Thanks, Straw...so I guess I add calcium through the Miracle Gro? I didn't know that Phosphorous mobility was so slow!

Straw thank you so much for that explanation! You just helped me figure out why some of my tomatoes burned so badly and some were fine after I put bonemeal on...the ones that handled it fine were in pots that I had run out of potting soil so mixed in manure, which would be a much more acidic soil to begin with, and the ones that burnt were in the plain potting soil!

Carol I remember my mom rinsing out almost empty milk bottles and pouring the milky water on her garden, she always said the calcium was good for the plants. I've taken up doing it too and I think it helps, with enough water added it doesn't go sour and stink. Maybe that would be a quick and easy fix?

Joey - that's a good idea!! I also remembered that I add lime...that has calcium. :) :) LOL Thanks so much for reaching out to help! :)