OK.
Just to recap what we already discussed, I said that most often when you get a color loss over a white base it is because nighttime temperatures for about two weeks leading up to bud opening is too high. That is generally a almost always true influence. Daytime temperatures matter too, but not nearly as much. In the trade circles, daytime or light cycle is referred to as D1, nighttime cycle or dark cycle is called D2. The best temperatures for color development during that two week period are 70-80'F D1 and 50-70'F D2
[ I'd like to jump ahead here and say why, but we need to discuss some other in general things first].
When you received your bulb last spring and planted it, it produced a pretty white flower with the pink edge. Working back to the previous year before you had it, it was under somebody else's control. Most likely a grower who grew this plant under optimum conditions and care. It was then stored over winter in a chiller/freezer at 31'F for it's semi dormant resting period to program itself for the next summer's performance ( which includes the pink edge). Which brings us to the point when you got it. So, then, the flower colors it produced for you the first year are the result of somebody else's control. Once you planted it, it became under your control and care. Many things we can control, we do, like feeding and garden maintenance and so on. But things we can't control are things like weather, climate and micro environment variations.
In order to understand how these factors affect color, we must first have a visual concept of a plants cell and what part controls color(s). Think of a cell as a hard boiled egg. The egg white is a jellylike material called cytoplasm. This part contains chloroplasts responsible for the greenery, like leaves as well as many, many other plant functions but no need to discuss that here. Now, think of the yolk part that is called a vacuole. The vacuole contains a group of flavonoids called anthocyanins that CONTROL petal color. They include the red and pink pigments called cyaniding, scarlet or brick red, pelargonidin, yellow carotenoid and so on. The potential for all colors and combinations (except blue) is always there even in a white flower. If it's not, it means the vacuole did not fill or was void of a particular color because it was blocked or did not release a particular color or any color at all.. In your case the pink over the white base. Why?
Well, you were on the right track when you thought you may have created a micro climate too warm during the semi dormant chill and reprograming cycle. The general rule in the trade is UNINTERUPTED 450 hours at 31-35'F minimum. In the garden, any interruption like a warm spell in the middle to later part of winter will alter the bulbs reprograming and affect several things, including shade, depth, tone and hue of color. So, you were right on with your thinking with that. But why then do we say the D2 nighttime temperatures are so important those last 10 days?
Well, it all comes down to pH. Not the pH of the soil but the pH of the cell during those last 10 days or so. Bud and flower color development occurs mainly at D2 nighttime. The varcuole also takes care of a certain amount of waste products which increase with temperature that lower the pH of the cell. The higher the D2 metabolic rate, the higher the waste load, the lower the pH. The color pink is particularly affected adversely, occasionally to a point where it won't show at all if cell pH is too low.
So, the conclusion of the story is: move your plant and hope for good weather next year. There
, could have answered your question in one sentence. But I recognized by your writing that you wanted to know a little more. Hope this gave you some of the info you're looking for. If not, just ask.
