One flower growing next to another, particularly different species can't affect the color of the other. Perhaps the blooms are fading in the heat, perhaps some extra nasturtium seeds have germinated? But the color of the nasturtium has nothing to do with the petunia. Linda C

Nazanine, "Admmad, the major problem here is that you are not talking about pure yellow roses" You are making the assumption that when Akheadbanger used the term 'yellow' that 'pure yellow' was meant. That is inappropriate. One cannot know that any yellow flower is pure yellow unless one examines the flower for all its pigments. One would have to show that there were no other pigments present in any concentration in such a flower with any absorption at any other wavelengths other than those that are labelled 'yellow'. I consider that the human eye is inadequate to label a flower colour as being pure. The examples you are giving are all either red / pink or red /pink with yellow, or yellow with red pink. In these of course there are anthocyanins, either masked or not. A masked pigment is not visible, by definition. Therefore, when an anthocyanin is masked because it is at very low concentration by a carotenoid at high concentration it is not visible as pink or any other shade. You are making the assumption that a rose that can make anthocyanins will show at least some red colouration all the time. I am not making that assumption. It clearly is not reasonable to assume that the human eye can identify all concentrations of one pigment included with another or that plants that obviously have different concentrations of red pigment cannot have low enough concentrations that are not visible to the human eye. In my personal experience, with other plant species, cultivars that show varying amounts of red over yellow pigments are clearly able to produce flowers that show no visible red at some times. Please re-read the quote regarding the colour of 'Masquerade' - the statement made is 'completely yellow'. The changing flower colour (Akheadbanger's) was yellow (of some sort that is unknown in exact shade and cannot be assumed to be 'pure yellow') at some point it then had a red pigment develop on its petal edges. That is the flower had both red and yellow in it just as the 'Masquerade' type flower was 'completely yellow' and then had both red and yellow in it. I am talking about PURE yellow, plain yellow with no other colours than yellow You are but it is unreasonable to make as narrow an assumption for Akheadbanger. We do not know that Akheadbanger's classification of flower colours is narrow or broad, that is, if an individual classifies flower colours as being white or yellow or orange or red or purple where would the intermediate mixtures be classified by that individual? You are also making the assumption that a yellow flowered rose that has the ability to develop red colouration will always show red colouration under all circumstances and at all times. That such flowers show different degrees of red colouration from being described as 'completely yellow' to being 'cherry-red' clearly indicates that the amount of red varies widely - but you appear to disallow the possibility that under some conditions there is no visible red in some such flowers (as in 'completely yellow'). It would appear that by your definition of 'yellow' a plant that produced a continuous range of red pigment concentrations had to always produce enough red pigment so that it would be visible to the human eye and therefore the flower colour would never be adequately described as 'yellow'. As an example, let's say if the red pigment concentration had to be 3% (of the yellow pigment concentration) to be visible in a yellow flower by your definition of yellow-flowered roses such a plant could not produce less than 3% (or the amount that makes the pigment visible to the human eye) red pigment under any circumstances. I do not make such an assumption. I assume that there may be cultivars that are capable of producing concentrations of red pigment below the human threshold of recognition as red pigment (say 0.01% as an example) which can then under other circumstances increase the production of the red pigment to visible concentrations The yellows contained no anthocyanins. Your definitition of the term yellow is unreasonably narrow and limited. Examine the table in the article. Yellow-blends contain anthocyanins. You are making the assumption that all yellows that contain anthocyanins show the anthocyanins. You are not considering the possibility that a yellow with less anthocyanin present than a yellow-blend such that it would not show any red in some circumstances would under the appropriate circumstances show red pigment (just as Masquerade does) and have been classified as a 'yellow-blend'. You are not considering the possibility that the methods used in that particular article could not detect very low levels of anthocyanins in all cultivars. You are not considering the possibility that the yellow cultivars chosen to be examined did not include a yellow that would then shade to red (perhaps because such a cultivar would have been automatically placed in the yellow-blend category) or just by chance. Another point, there are protocols for extracting anthocyanins Of course there are very sophisticated ones, but that does not mean that simple procedures cannot also provide acceptable results. You can not just put a tissue in warm water and expect the anthocyanins to be expelled from cells because . Actually you can, I have and they do. This website describes extracting anthocyanins from red cabbage with boiling water http://chemistry.about.com/library/weekly/aa012803a.htm One does not need to use boiling water, water from a hot water faucet does work with flower petals. Boiling water destroys the tissue structure, depending on the temperature of the water used the petal structure can survive the treatment and still extract some of the anthocyanin pigment. If is was this simple there would'nt be so many red-coloured flowers in the tropics. My apologies, but I did not mean to imply that warm water was rainwater warm. The temperature of the water needs to be high enough that it breaks down some of the epidermal cellular structure (but if you want to save the petal structure not so hot that the petal turns to mush). The presence of kaempferol and quercetin does not necessarily mean that red pigments are present You are misinterpreting my statements related to the presence of kaempferol and quercetin. You made the statement "So since the plant is not supposed to have reds, and under no circumstance are anthocyanins produced in tissue where the pathway is non existant, for me at least, anthocyanins are not involved." Since the presence of kaempferol and quercetin in all rose colour classes indicates that the pathway is indeed present in all rose colour classes then your statement regarding the non-existence of the pathway is not relevant. Akheadbanger, under your narrow definition of the term yellow and your wide definition of the term red, both as used by Akheadbanger you consider that the red colouration is likely to be a carotenoid pigment. From the analogy of rose cultivars such as Masquerade and Charleston (which has been shown to have carotenoids when yellow and anthocyanins when red Phytochemistry 12:1783-1786, 1973) I consider that Akheadbanger's flower may have much lower concentrations of anthocyanins than those two examples such that in certain conditions the flower can be described as yellow because of its carotenoids and under other conditions it can show red tinges because of increased anthocyanins. Since it is known that specific roses can have high carotenoid and low anthocyanin pigments sometimes and then produce more anthocyanins at other times I consider that sort of explanation more probable.

Does it start out white and then become yellow? I have one that blooms white and turns a salmony-orange as the bloom ages.

It's amazing that this old post has come to life again. John, I do believe you are correct about the PH, but could it be 'wrong' if they bloomed? Maybe different? Since this post, I had the experience of moving pink peonies which had stopped blooming because a tree grew and put them in too much shade. I relocated them to a full sun bed and they eventually bloomed with the same colour. The soil is approximately the same since we have put down topsoil on all the gardens. I am looking forward to their blooms right now. Today I went out and staked them and they are loaded with buds. They make such lovely cut flowers.