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Effects of fertilizers on bloom color and health of plants

July 9, 2014

2011 & 2012 were dry summers in my Chicagoland. My water-bill was doubled, but my roses were stingy, some Austins didn't bloom. I gave them tons of tap water, hard-well water at pH 8.

2013 summer I watered much less, but fixed my tap water with sulfate of potash & gypsum & molasses. Got over 40+ blooms on many roses, even for 90+ degree days.

2014 we had a cold & drier spring, I used sulfate of potash with chicken manure. Got 70+ blooms on Frederic Mistral, but blooms were washed out to white and deformed. So I threw gritty lime stones, plus red-lava rocks. Blooms became well-formed, and darker pink. I realize that sulfate of potash promotes MORE blooms, but I need calcium for better-bloom-formation, and trace elements in molasses or red-lava-rocks for better bloom color. See below for Frederic Mistral's cluster, after lime-application, but before red-lava.

Comments (26)

  • strawchicago

    I already posted in the thread "Molasses for Nematode ..." pictures of Sonia Rykiel and Evelyn became dark pink, through watering with Wholesome Organics blackstrap molasses (high in iron, plus trace elements).

    We got so much rain this year ... found a lazy-way to deepen blooms' color: throw some red-lava rocks, and let the rain (pH 5.6) break that down. Red lava rocks is high in potassium , iron & boron, plus trace elements.

    Below picture shows the effect of red-lava rock. Leftmost red is Yves seedling #1, it had been light-pink sometimes for 2 years, until I stabilized the color to red. I learned that trick from my neighbor, who complained that the pink-knock-out she bought, turned gaudy red, after she mulched with black-lava-rock.

    The deep-pink blooms are Evelyn. Red-lava rocks gives Evelyn an orange-shade, which I like more than the deep-pink made by molasses. Golden Celebration rose behind also became deep yellow.

  • strawchicago

    Here's another shot of Golden Celebration rose to show its deep-yellow color. The color is nice, but the quality isn't as good as when I used both horse manure & cow manure on a 1st-year own-root.

  • strawchicago

    Below picture, the gritty-lime gave calcium to pro-long the vase life of blooms, the petals are super-firm. The red-lava rocks deepened the colors of both Frederic Mistral and Golden Celebration:

  • strawchicago

    This last picture, taken July 9, shows the effect of fertilizers on blooms:

    Left orange is Summer Samba, fertilized with MiracleGro soluble for roses. This plant has the worst black spots in my garden. It's planted in 100% MG moisture control potting soil, without gypsum, watered with rain at pH 5.6. The petals are thin & soft, doesn't last long in the vase, and the bloom is deformed. Last year the blooms were much bigger & firmer since I fixed my water with gypsum & sulfate of potash.

    Small white blooms are Mary Magdalene, poor quality compared to when I fertilized with horse manure. Only chicken manure, NO gritty lime nor red-lava.

    Bottom: Tiny dark-pink bloom is Christopher Marlowe, only chicken manure, NO gritty lime nor red-lava. Next to it is pink Radio Times, small-bloom thanks to too much sulfate of potash, which promotes cluster-blooming of many blooms per branch.

    The 3 biggest and best-quality blooms are: peachy-pink Evelyn in the middle, red W.S. 2000, and yellow Honey Bouquet.

    Evelyn & W.S. 2000 gets chicken manure & red-lava-rocks & gritty lime ... but no extra sulfate of potash, thus less cluster-blooming.

    Honey Bouquet gets special treatments since it nearly died this past winter: No red lava rocks, but I used soluble Pennington Alaska pellets, NPK 4-6-6 with kelp-meal for best color. I use that "tea" for wimpy plants near death. That brewed-tea revived my wimpy tomato plant, which almost died from 1 cup of bone meal in the planting hole.

  • strawchicago

    Here's the deep pink Evelyn made by molasses & gypsum to fix my pH 8 hard-well water:

  • jim1961 Zone 6a Central Pa.

    Nice reads Strawbhill! I should be getting our soil test results back soon...

    I sent pure native soil that was approx. 10 inches deep...

  • strawchicago

    Hi Jim: I would love to know the results of your soil test, thanks in advance. When I submitted 1 cup of my soil to EarthCo. for testing, they recommended amendments tailored to the crops grown. I put down "Rose and tomato", so for my soil pH 7.7, they recommended gypsum and sulfate of potash.

    There's an agriculture report for soy-bean crop, where the use of sulfate of potash and lime pellets BEAT the yield of fungicide & chemical fertilizer. Below link also showed DOUBLE hay production with 1/3 gallon of kelp & sulfate of potash and 1/2 gallon of soluble bone meal.

    It's similar to my brewing tea under hot sun with Pennington Alaska NPK 4-6-6 with alfalfa meal, fish bone meal, sulfate of potash, and kelp meal. I'm going to reduce the sulfate of potash I use, since I don't like cluster blooming, hard to cut for the vase, and each bloom is smaller. Below is Summer Samba last year, when it was fertilized with molasses and gypsum, and LESS sulfate of potash, resulting in one bloom per branch and bigger bloom:

  • jim1961 Zone 6a Central Pa.

    Nice orange! I'll let you know the results of our soil test as soon as I know it.

    Last soil test that company told me not to apply any fertilizer unless I seen a Nitrogen deficiency in our rose leaves.
    PH was 6.5 at that time... Soil was taken from approx 3-4 inches deep...

    I planted 6 petunias out in the backyard and they are mulched with shredded wood chips. Three of them I gave 5-5-5 Life Dr Earth fertilizer and three of them I did nothing. These were all planted latter May.
    All three petunias that I gave nothing to are growing and blooming better up to this point. (Sort of surprised!)

    The Petunia I planted in that bucket with MG potting soil is doing the best... 5x better than the rest in growth and blooms...

  • KnoxRose -7a

    This is very helpful, thank you for sharing your findings! I was literally about to post here asking if there is any certain combo of nutrients that might increase flower size because certain roses of mine seem to keep shrinking, I know heat plays a part in this, I am just hoping to encourage the largest flowers possible for any given weather. I saw a post you put up at some point about molasses being the key to getting the deepest color possible from your roses, I picked some up the last time I was at the store & I am very excited to try it on my Ebb Tide.

    as always, thank you!


  • strawchicago

    Hi Jessica: So glad you ask the question about how to get the biggest bloom, I wonder the same. The largest blooms on my roses were: 1st year own-root, fertilized with cow manure, horse manure, or cocoa mulch, plus plenty of water .... regardless of the temp. I think balanced fertilizer, at the right ratio is the key to biggest bloom.

    I got huge blooms from horse manure, cow manure, and cocoa mulch. Here's the composition of cocoa mulch, pH from 5.4 to 5.8, NPK 2.5 - 1 - 3 (highest in potassium), plus 43% carbon. Ratios in mg/100g: 1000 phosphorus, 3251 potassium, 575 calcium, 488 magnesium, 40 iron, 9 manganese, 11 zinc, 3.5 copper, plus trace elements.

    My current experiment with chicken manure & sulfate of potash & gypsum produce too many cluster-blooms, great for landscape, but not for cut flowers. In contrast, my 3 years with horse manure & alfalfa meal produced big blooms, one per stem, rather than clusters.

    The bouquet with the biggest blooms were picked last summer over 80 degree heat, mulched with cocoa mulch, horse manure, and alfalfa meal. Cocoa mulch gives the blooms the "ruffle effect". I think slow-released, organic low-dose fertilizer is the key to big blooms. See below:

    This post was edited by Strawberryhill on Wed, Jul 9, 14 at 18:33

  • strawchicago

    Hi Jim: I have the same experience as you do. I put Jobe's Organic NPK 2-7-4 around 4 geraniums, but the remaining two I did not. There's no difference in flowering, except the fertilized ones are just a bit taller. However, the tomatoes planted in fluffy potting soil mixed with my heavy clay, are much bigger than the ones planted in my native clay. Roots can grow better when the soil is fluffy.

    This bouquet was picked last August 3, during high heat, watered with my tap water, pH 8, but fixed with soluble gypsum. I didn't order sulfate of potash until much later. The horse manure & cocoa mulch & calcium from gypsum gave the blooms better form, and bigger blooms. For that reason I won't use sulfate of potash, unless the rose is stingy.

    This post was edited by Strawberryhill on Wed, Jul 9, 14 at 18:37

  • jim1961 Zone 6a Central Pa.

    (Our neighbors tomatoes in the background in pots...)
    Soil is regular MG potting soil. He fertilizes with MG fertilizer for tomatoes (18-18-21) at 1/2 strength once per week.
    Huge and they are setting a lot of fruit.

    One of the buds opened on our Carefree Sunshine bush today. That's only the 5th bloom of the season for that bush. I gave it Brewers Yeast today...

    This post was edited by jim1961 on Wed, Jul 9, 14 at 19:17

  • strawchicago

    Hi Jim: Only a taste-bud can detect the difference between chemical fertilizer vs. organic. I used to grow lots of herbs: Oregano, sage, cilantro, Rosemary, Parsley, dill. I bought an MG sprayer with fertilizer attached. I had too much fun squirting that stuff on my plants, including herbs. They grew big, but NASTY taste ... the flavors were extremely harsh, I could not use in cooking.

    Same with the rose park, they use chemical fertilizer high in phosphorus. Frederic Mistral was fragrant, but a harsh scent ... even my kid could not stand it. I hesitated on Fred for that reason, until folks in Rose forum raved about his scent. I grow Fred with organics, and the scent is wonderful. Julia Child's licorice scent is MIGHTY STINKY at the rose park, worse than cough medicine.

    Same with veggies. My Mom grew the sweetest corn & veggies in MI ... her land used to be a chicken-farm. When I checked on Chickity-doo-doo, a reviewer stated that the veggies she grew are super-sweet on that fertilizer.

    Chicken manure is high in boron, zinc, and copper, thanks to the minerals added to their diet. Zinc and copper are anti-fungal agents. My fruit trees were stingy for over a decade, until I put Lily Miller acid fertilizer (with lots of chicken manure & mighty stinky) .. and the cherry tree was RED with fruits, the peach tree's branch got broken (too many fruits) ... it's amazing. I used chemical 10-10-10 on my fruit trees before, they were still stingy.

    One lady, the owner of a fruit orchard, wrote on how she had her soil tested in trace minerals ... her soil was deficient in boron. Adding that missing ingredient made a BIG difference in her fruit production. I grew tomatoes in pots before .. they taste lousy compared to tomato grown in my dolomitic heavy clay.

  • seaweed0212

    Here's Tess of the d'urbervilles, an Austin rose in my southern CA garden. I fertilized with diluted chicken manure, plus gypsum. The color is good red crimson, myrrh scent that I love. Picture taken July 8.

  • strawchicago

    Hi Seaweed: I love that red color of your Tess, and perfect symmetry. I kick myself for taking that off from my buy-list to buy Scepter'd Isle instead. I didn't know that Tess has a better myrrh scent than Scepter'd Isle. I ended up giving Scepter'd Isle since it smelled like stinky socks in my alkaline clay. What else to you fertilize Tess with to get such awesome color? Thanks for the info.

  • seaweed0212

    I use fish emulsion on my roses. Lovely day thanks to these cut today, July 11:

    Roses from the top L2R: Dream come True, Red Masterpiece, Red Olympiad, Tournament of Roses, Anna's Promise, Gardenia, Austin C R Mackintosh, Heirloom, Sharifa Asma, Princess de Monaco, and Chrysler Imperial.

    strawchicago thanked seaweed0212
  • seaweed0212

    Tess is my special rose, because I obtained it on my mom's passing anniversary, only one at nursery 2006, planted north, front yard, at bottom hole soaked with one cup gypsum when first planted in the ground. Kellogg's organic plus soil, over the years, I have put Eleanor's VF-11, fish emulsion, Vigoro's rose food, all purpose plant food with 2% humic acid, NPK 4-8-2, besides the very diluted own chick manure (raise own chicks at far corner of back yard since 2012), so this plant enjoys all sort of fertilizers and getting this consistent crimson color and each one smells intoxicating, you really have to be here to know what I mean.

  • jim1961 Zone 6a Central Pa.

    I never tasted a tomato that was fertilized with MG.

    Tess does have a nice shade of red Seaweed. Does it glow?
    All great looking roses in your last pic! :-)

  • seaweed0212

    Dear Jim:
    Tess does not glow, but it is very solid color, photo may not be true to the red color if sun shines upon, sometimes also depends on the camera, this one taken at dawn, shows closer to the true crimson color. Good to cut it fresh like this and leave it in the vase, to preserve the color and the scent, it will last longer too. Noon time CA sun changes the beautiful color and fragrance fades soon. Tess can stay as good as 5 days sometimes if under 70F, scents stays 3 days or longer, Tess is one of my favorite English crimson roses.

  • strawchicago

    Hi Seaweed: I adore your Tess, such pretty red color. My sister in CA sent me pics of her garden .. she has a bright red front door (same color as your Tess). I love that red color ... so glad that my neighbor painted her door from blah-white to deep-red, so cheerful !!

    For 15 years we used Scott's Weed & Feed in our lawn, VERY EXPENSIVE at $20 for 15 lbs. I still have bad infestation of dandelions, and spent ungodly amount of time digging dandelions with a long shovel. Honestly I spent more time killing dandelions, than taking care for my 50+ roses. Our lawn is always pale-yellow, even when I spend near $100 per year on Weed & Feed.

    The I learned about the dangers of the herbicides in Weed & Feed, 2,4-D has been linked to cancer. An excerpt from link below: "The weedkillers (phenoxy herbicides) used in weed ‘n feed products are persistent, bioaccumulative toxic substances linked to cancers and to reproductive, immunological and neurological problems. Some of the herbicides in chemical weed ‘n feeds��"especially 2, 4-D��"have been linked to increased rates of cancer in people and dogs."

    So I bought Milogranite, NPK 5-2-0, with iron. Here's the info. from their website "Milorganite is manufactured by the Milwaukee Metropolitan Sewerage District. The District captures wastewater from the metropolitan Milwaukee area, including local industries such as MillerCoors. This water is then treated with microbes to digest nutrients that are found in it, and cleaned water is returned to Lake Michigan."

    "The resulting microbes are then dried, becoming Milorganite fertilizers ... This produces a semi-solid form similar to wet cardboard that is subsequently dried in twelve rotary driers at temperatures ranging from 900⁰ - 1200⁰F. Any surviving pathogens are killed from the extreme hot temperatures. Research indicates Milorganite's odor is effective in keeping deer from browsing plantings up to 5 weeks."

    *** From Straw: the smell is Milorganite is mild, compared to mighty-stinky chicken manure. The lush & dark green on my lawn is AMAZING. In 15 years, my lawn has never been that good. I sprinkled it liberally around trees, where it's thin & sparse grass ... and that area because dense & lush sod within a month.

    I'm going to use Milorganite, NPK 5-2-0, along with granular sulfate of potash for my roses. Will report the result, my roses are always pale, just like my lawn, at our pH 7.7 alkaline clay. I visited 2 neighbors who paid $200 for professional lawn-fertilizer. One chose chemical-method, the other chose organic-lawn-care (Milorganite).

    BIG DIFFERENCE between the 2 lawns !! The one with Milorganite is thicker & denser & lusher lawn, the one with chemical fertilizer is thinner & paler lawn. It saves me $$$, since Milorganite is only $9 per big bag, compared to Scott's Weed & Feed at $20 per 15 lbs., and that didn't help to control my dandelions either.

    Here is a link that might be useful: Reasons to avoid Weed & Feed lawn fertilizer

    This post was edited by Strawberryhill on Thu, Jul 17, 14 at 15:35

  • strawchicago

    Milogranite website has an excellent explanation for how each factors work in NPK (nitrogen, phosphorus, potassium). Here's an excerpt from below link:

    Nitrogen Governs overall plant health and growth above-ground. Accelerates growth and deepens the green color in grasses. Nitrogen should be applied with a balanced hand ��" too much makes plants grow quicker than their roots can support.
    P Phosphorus The essential element for strong root development. Plants with proper amounts of Phosphorus are also more resistant to disease and have improved seed production, fruit growth, blooming and flowering.
    K Potassium Potassium plays more of a behind-the-scenes role than Nitrogen or Phosphorous, but still is necessary for optimizing plant health. Potassium improves water retention and disease resistance while protecting plants from cold weather.

    **** From Straw: will post pics of roses tested with Milogranite and sulfate of potash later.

    Here is a link that might be useful: [Milogranite with NPK 5-2-0(http://www.milorganite.com/Lawn-Care/Lawn-Care-Basics/Fertilizer-Basics.aspx)

  • strawchicago

    While checking on which form to use with Milogranite, sulfate of potash in powder form, or granular form. I came across this Australian site, with the below info.:

    "The addition of Sulphate of Potash at pruning, early Spring and Autumn, will thicken cell walls and strengthen stems of the plant to help guard against Black Spot. Sulphate of Potash will also intensify the perfume and colour of the flowers. Advantages: Bigger and tastier fruit and more flowers and colour."

    Two people in Antique Rose forum already used Milogranite NPK 5-2-0 on their roses:

    •Posted by terryjean 5 Central IL (My Page) on Tue, May 29, 12 at 16:42

    Hi Sally - I switched from RoseTone to Milorganite this year because of the price. I have 300 roses and it's just too expensive when you're on a fixed income and need to feed every month. I can get 36-lb. bags of Milorganite for $5.99 on sale at Farm & Fleet, so I thought I'd try it. Anyway, the roses exploded and are the biggest and most robust that I've ever seen in 5 years...the blossoms are even deeper-colored hues and more plentiful. My hubby, who does the fertilizing, remarked that the roses are so lush that he is having a hard time getting in between the beasts because of their size. I've had a bounty of blooms this year on some of the more fussy ones like 'Soeil d'Or' and more basal breaks than when I used to brew alfalfa tea. I have even spread Milorganite on the hostas and the deer are staying away...another great bonus. The roses and other plant life around here seem pretty satisifed and my wallet is happy.

    •Posted by saldut 9-10 st pete, fl (My Page) on Tue, May 29, 12 at 17:07

    Hi Terry- That is a great price for Milorganite, I pay $12.95 for a 40 lb. bag @ HD, and can't seem to find it any cheaper... I go thru' 2 bags every month or so but put it around everything, and on the grass."

    Here is a link that might be useful: Australian site on sulfate of potash

    This post was edited by Strawberryhill on Thu, Jul 17, 14 at 15:29

  • strawchicago

    Althea from MN posted excellent info. on Milorganite in Organic Rose years ago, which I re-post below:

    •Posted by Althea z4 MN (My Page) on Sat, Aug 7, 04 at 9:00
    Milorganite� 2003 Summary Table E (for Exceptional Quality) 2003 Weekly Composite Samples Values are parts per million, dry weight = milligrams per kilogram (mg/kg)

    Average for Year, N = 52

    Arsenic 41 mg/kg 1.4 mg/kg Less than 1. = LOD to 4.2

    Cadmium 39 mg/kg 3.7 mg/kg 3.2 4.7

    Chromium No limit** 170 mg/kg 140. 220.

    Copper 1,500 mg/kg 230 mg/kg 200. 250.

    Lead 300 mg/kg 57 mg/kg 34. 77.

    Mercury 17 mg/kg 0.49 mg/kg 0.35 0.79

    Molybdenum Likely to be 40* 12 mg/kg 10. 14.

    Nickel 420 mg/kg 23 mg/kg 19. 36.

    Selenium 100** mg/kg 4.5 mg/kg _4.1 = LOD 6.1

    Zinc 2,800 mg/kg 510 mg/kg 400 610

    These levels are below EPA limits, but still present in the product, at least as far back as 2003.

    **** From Straw: the anti-fungal nutrients of zinc, copper are very high in Milogranite .. good stuff for roses !!

  • ziyouzizai

    Hi Straw, thank you for the detailed post. I'm in Chicago too and have a few David Austin roses that didn't flower as well as prior years (Tess, Claire, Georgia, Shalott). Not sure if they are all suffering from Potassium deficiency or what. Is it too late to give them a dose of Milogranite now? Also, can I soak the red lava rocks in water and feed the roses with that solution?

    strawchicago thanked ziyouzizai
  • strawchicago

    ziyouzizai: Sorry for the belated response, have been busy killing japanese beetles and cutting blooms for the vase. It was in 2014 that I tested Milogranite in pots, and the flowering WAS NOT as good as MG-soluble for roses NPK 20-20-20. Milogranite practically has zero potassium.

    Fantastic idea to soak red-lava-rocks in ACIDIC rain water, I tested it for the past 3 years and that works really well. Since pH of red-lava-rock is high at 8.2, one needs an acidic agent, like rain-water at pH 4.5. If rain-water is not available, I put gypsum (19% sulfur) and vinegar in a bottle with red-lava-rock, along with my pH 9.1 tap-water (very alkaline).

    That's cheaper than buying sulfate of potash NPK 0-0-50, works well, but doesn't have the iron & trace elements like red-lava-rock. Also if your roses are grafted on Dr.Huey, they flower tons in the 1st year, but will be stingy in the following years, UNLESS THEY GROW THEIR OWN ROOT. But even if they grow their own root (on top of Dr.Huey), they can't bloom as well as the ones bought as own-roots.

  • ziyouzizai

    Thank you for your insight! I ordered mine from davidaustinroses.com in 2015 Feb and the order said own root except Margareta...Teasing Georgia - Own Root (Ausbaker) - Bare Root Roses; Lady of Shalott - Own Root (Ausnyson) - Bare Root Roses; Claire Austin - Own Root (Ausprior) - Bare Root Roses; Crown Princess Margareta (Auswinter) - Bare Root Roses. I will need to be more vigilant in feeding them regularly and
    properly I am glad the japanese beetles are slowly disappearing! I never use any trap and have only been knocking them into a 32oz yogurt tub with a trowel and smashing them, then discarding the bodies on the road. Birds and squirrels tend to clean them up for snacks since I never see any remains the next day.

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