Codiaeum variegatum 'Petra'

PeggyTX

I have two of these lovely plants Crotons potted in rather large pots in my front garden (south side of the house).  They are shaded from morning sun until about 9am.  Then they get dappled sun for a couple hours. Full overhead sun hits them for approximately 4 hours a day.  That's as much of our searing hot summer Texas heat I think they can stand, actually.  They only get hot afternoon sun for maybe 1 of those hours, then welcome shade from my neighbors tall oak trees shades them in the hottest, late part of the afternoon. 

My question is, why do you think have they stopped producing the pretty red, orange and coral leaves they had when I bought them?  You can see they had more colorful leaves at the bottom of the trunk in my photos.  But sadly all the new leaves are emerging mostly green and yellow. Am I not fertilizing them enough? Will excessive heat cause this?  I know they don't like to be moved around, and I think they are happy in their current spots out there.  Any thoughts or suggestions to get some color back into their "cheeks"?

PeggyTX

Sorry to have bothered you all.  I just realized this plant probably isn't hardy in Britain and you all are unfamiliar with it.  As the kids say these days, "my bad".   I'll ask this question on my Texas forum.

Ceres

They are houseplants in this neck of the woods.

PeggyTX

That makes sense.  Do they tend to get the bright red, coral and orange leaves indoors?  Or do they do what mine is doing and stay mostly green and yellow indoors?