I have several conifers that have been selected for their winter colours: Pinus sylvestris ‘Aurea’ (6 years in my garden), Pinus Mugo ‘Ophir’ (4 years), Pinus mugo 'Winter gold’ (4 years), Pinus Mugo ‘Zundert’ (3 years), Abies concolor ‘Wintergold’(2 years), Pinus strobus ‘Hillside Winter Gold’ (2 years). They were all bought late Fall/Winter and had the most beautiful golden tones when I bought them from local and Dutch suppliers. My problem is that they never displayed those colours again; they remain green throughout the winters. I have been wondering the reasons for this? Books on conifers only mention two factors: - Cold: I live in true zone 8 and lows are down to -10°C each winter with one or two weeks when the highs remain below freezing. So cold is probably not the reason. Also local nurseries have good coloured plants. - Sun: They are planted in an area where they see full sun from noon to sunset and the afternoon sun is hot here. So sun is probably not the reason. I think there must be something else, something probably missing in the soil which may be needed by the plant to change colour. My soil is clay heavily amended with yearly additions of compost/mulch which I thought would provide all nutrients and, as a result, I never fertilized them. Just to give it a try I added some P-K fertilizer to each of them two weeks ago (a little late though for fertilizing but temperatures were above 10 °C for several days) and today I’ve noticed a discernable yellowing in most of them. So, my question is, what do you think of this? Illusion or delusion? Is it the P or the K that is important? To make things more complicated, last month I was visiting a Dutch nurseryman specialist in dwarf conifers and, when I mentioned my problem to him, he avowed that often plants grafted from the same mother and grown in containers side by side would display enormous variability in the winter colours, some staying green altogether. He did not know why. Gomero
I guess understanding the process for Winter color changes is not sufficiently clear. Web searches do not bring much. The same could be said of bark color changes in maples. In order to definitely separate climate from soil, I have purchased another Pinus mugo 'Winter Gold' from a local supplier, beautifully golden and I'll keep it in the same pot, next to the ground planted 'Winter Gold', for another year to see its behaviour. I am puzzled by this and I need to figure it out. Gomero
I have also been interested in this topic. We find that some conifers with golden winter color do not color well for us in our garden. Our speculation has been climate, i.e, lack of summer heat- often we see a plant in the Willamette valley in Oregon with great color, that does not color for us near the Canadian border. Our summers are quite cool, compared to Oregon's, and that seems to be the main climatic difference. But that may not be it, as I understand you live in a climate with adequate summer heat. One question about your siting- you say the plant gets full sun from noon til sunset. Is this winter sun or summer sun? It may be that it needs more winter sun than it is getting...just a speculation. I have a "golden" hinoki that does not get winter sun, and even tho it gets some summer sun, it stays green to yellow green.
Hi Silver Creek, Thanks for your contribution. I can most definitely exclude the lack of Summer heat as the cause since in my climate we have hot, dry summers that most conifers are supposed to like. Whereas in Holland or the UK, with much cooler summer weather, the colors, as I have witnessed, are superb. It is summer sun. My problem conifers probably receive more sun in the winter than in the summer since the mature oaks that screen the sun in the summer are leafless in the winter. Anyway I understand that colors may start changing as early as October and that by mid-November they have reached their best, so this seems to imply that winter sun plays a minor role. Little by little we'll make progress. Gomero
Hi Gomero, I am under the impression that winter sun is not a player as to your conifers color in the winter. My Pinus mugo 'Zundert' which I have posted in the conifer photo section of this forum is in complete shade from late November to late March. Color transition begins the first of October in zone 5b Kansas City. My guess is you are to far south (zone 8) for good transition from green to gold to occur. Yes your nursery has them for sale and they are gold but where did he have them shipped in from. Ask your nursery man who the grower was. Dave
I've seen quite yellow golden conifer forms here (USDA 8). A. Bloom's books show good results in his Foggy Bottom garden in England also. It IS located in a "foggy bottom" where it may be colder than surrounding areas (although when I was there it didn't seem so much down in a hole as merely on the level (more or less) rather than up high or on a hillside).
I also forgot to mention your micro climate could have have an impact as to their ability to change seasonal colors. Dave
Resin, If that's English paint it won't work. Has to be imperialist USA paint. Sold in pints or quart ( US liquid) sizes. Dave
LOL. I once visited a small live Christmas tree grower who painted his Deodar cedars with a spray on bluish water based paint (apparently they were quite chlorotic).
What do you mean by far south?, latitude?, if so, please look at a world map, Toulouse is at about 44° North and Kansas City at about 38° North, thus, if anything, Kansas City is south from Toulouse. If by far south you mean that Toulouse is warmer than Kansas City, then I agree. But then how to explain that, as Ron says, the conifers color very well in the UK where, for the most part, they are in a zone 8 warmer than mine. The same for the warmer oceanic regions of France. No, it does not fit together. As I said above I have bought a beautifully golden pinus mugo 'Winter Gold' which I have placed, in its undisturbed pot, side by side with my (pale green) pinus mugo 'Winter Gold' which is in the ground, next Winter I will tell you the result: climate or soil? Gomero P.S. Resin, you have already proposed that solution. Try something else ;-))
After this is resolved we can figure out why same cypress family conifers have sheared appearance in some areas and open habit in others. At first it appears to be associated with climate, the close-growing trees appearing in cooler areas. But it's not consistent.
Last Christmas some guy in my neighborhood sprayed this aerosol white paint/ goop on his huge very old juniper shrubs to imitate frost. We dont get snow here. Most of it was still there this year. So thats one way...I guess. To figure it out I guess you need to first understand the physiological mechanism that affects the coloring, habit, whatever with some certainty. Then you need to isolate the numerous variables that can affect that mechanism and test them. It's probably more complicated than just one thing. (i.e., may not be just hot summers b/c one climate that has hot summers may have or lack another variable that is important) If you could figure it out then you could probably develop a synthetic hormone product to make all of our conifers turn golden in the winter (besides paint of course)
