What makes a creeping jenny turn real yellow? It's in a greenhouse now. Do they need fertilizer? More sun? Less sun? Do they like to be kept moist or more on the dry side?
The color is most likely due to the cultivator that you have of Creeping Jenny.
The variety Aurea has yellow leaves. Many times a grower uses a general tag that has the 'Creeping Jenny' name.
Here is a link to refresh you on the care requirements.
Read more at Gardening Know How: Growing Creeping Jenny: Growing Information And Care Of Creeping Jenny Ground Cover https://www.gardeningknowhow.com/ornamental/groundcover/creeping-jenny/creeping-jenny-ground-cover.htm