having done some research, I think you must be talking about Euphorbia tirucali 'Fire Stick' - when new growth occurs, those branches will be rosy red, fading to green as they age, meaning the plant is green unless it has new growth. If you don't have that particular variety of this plant, it seems there's no red growth at all.

Two things are required for the red color: a certain amount of chill--but not frost--and a little direct sunlight. If you move it to a cool room with a sunny window, you will probably get some color. The ones at Lowes have probably just come from a cool greenhouse. Without those conditions, the "sticks" will remain a lime green color. If they refuse to color up, and are more of a medium green than lime green, then you may have been mistakenly given a regular Pencil Tree (Euphorbia tirucalii), instead of the 'Fire Stick' variety.

tugbrethil, I wondered about the chill factor, but the info on line re E. 'Fire Stick' was quite categoric that it was the new growth that was red, and didn't mention chill factor. Which is correct - that it turns red after chilling, or that the new growth is red? I'm curious, that's all....

In warm weather, or with regular warm house temps, the new growth is a yellowish lime green, sometimes with a barely noticeable bronze tint. It may be that summer night temps outside in the UK are cool enough to color it up some, but I have my doubts. Low light intensity will also stymie the color.

Funny enough, all the info I found about this plant was on American sites, doesn't seem to be all that popular over here. So I'm still confused about whether the new growth is red (if its grown outside) or whether all the growth turns red when fall/winter arrives.

Well, the new growth in summer is a yellowish lime green. As the nights cool in fall, the whole plant develops a reddish bronze cast, which shows up as intense oranges and scarlets on the new growth, which has less chlorophyll to mask the red pigment. The inner--and usually older--parts are usually greener, because they are more sheltered from sun and cold. If it doesn't get intense enough light, or cool enough temperatures, it doesn't turn red.

Thanks, Tug - that's the complete opposite of what the info by a seller said online, just goes to show you can't trust a salesman, can you, lol.

Too often, Bamboo, the salesmen don't know--at least that seems to be the case with many of my suppliers' vendor reps! : D