Problems with Yellows

If there is a thread that addresses this already, please feel free to direct me to it instead of humoring me.

This winter I lost several yellows I was really looking forward to growing out, especially Flame and Goldfinch. This is my second year to lose Goldfinch over a winter. Winter before last, I left a large GF out with the others in 5-gal. pots, and it didn't come back. This winter, Flame and GF were fall purchases, so I potted to 1 gal. from well established 4" pots. I tried to keep them barely moist, but dryish at the surface to avoid any rot problem. I believe I even used a Banrot drench when I potted them. But, by late winter, they went soft at the soil line, and that was it.

Héloïse held out until I put them outside, then did the same thing.

Is it something I did? Is it something I said? My breath? Do I have to give up on these varieties?

Are there preventative measures I can take? Affordable chemical treatments?

Are there fool proof yellows I don't know about?

I have a special affection for these three, but I don't want to throw good money after bad........

Does this mean you left the pots outdoors? Potted Brugs need to be overwintered indoors regardless of color. Plants in pots are more vulnerable to root damage in freezing weather. If the soil freezes, so do the roots.

Like you, I love yellow Brugs, but haven't really associated Brug death with color. I have lost 3 Becca Lynns and 1 Citrine, but figured they needed to remain dryer than other Brugs. This past winter, I set the thermostat to 50ºF instead of the usual 45ºF and didn't lose any Brugs nor did I have any die back. My Goldfinch, Gypsy Queen, Jamie, Jamaica Yellow, Bernstein, Charles Grimaldi, Cleopatra, Daybreak, a yellow noid that resembles Lemon Twist, Ludger's Summer Dream, Sunkissed, and Tropical Sunset all made it without a problem. Most were in 1 gallon containers. My winter conditions may be different from yours. Here, because of the wildly fluxuating winter temperatures, my Brugs don't go dormant. They just slow down. I did raise the thermostat by 5º this past winter and I fertilized about once a month with full strength Miracle Grow. I saw a big difference in their health.

Where did you overwinter your Brugs? How cold did it get? Is it possible the soil dried out too much? Or were any of the transplanted Brugs repotted just before the temperatures dropped? Brugs in pots with too much soil (soil not populated by roots) stay wetter much longer than Brugs that have been given time to fill the pot with roots before winter sets in. The first group of Brugs are more likely to have root rot even though you let the soil dry out between waterings. This is more likely to happen if the temperatures are very low. Brugs aren't as efficient at taking up water at low temperatures. So any conditions that encourage water retention may lead to root rot. When you watered, how much water did you put in each pot? How much light did the plants get? When you watered, did you water all the pots? Or only those that needed more water?

You don't have to give up growing yellow Brugs. You may have to change your overwintering practices. Note I keep 'water' as the common theme in my questions. That's because water is the most common Brug killer especially during winter.