I Noticed this today, I am a hobby Grower so I don't have Acess to a lot of chemicals... Please can you tell me what is wrong and how I can fix it
Thank you

The symptoms appear to be a nutrient deficiency, possibly magnesium. A tissue sample would confirm. Check with a local university, they should be able to recommend a lab that can perform tissue analysis.

What are you fertilizing with and how often?

Hi, Tech help
Thank you for replying...
OK To answer your Question I use Babybio, Compound Fertilizer 10.6:4.4:1.7 I Started using this one as the Fertilizer I used last year on my Big Red was Tomerrite and the leaves were paler and the colouring was Not as good as it could of been, so I changed it to Baby Bio, the leaves on Big Red look OK, that's why I was asking... It does say to feed every two weeks, so I coming up to a feeding....
I Hope that Ramble makes Sense
Thanks for all your help

NineCrow -

The fertilizer you are feeding with is not supplying enough of the major nutrients. Try a 20-10-20 or a 20-20-20 and change your frequency that you fertilize to once weekly until the new growth is normal then go back to fertilize twice monthly while the plants are actively growing.

Thank you Tech Help

It's only on a few of the Leaves, all the new Leaves are OK And ALL the Leaves on my other poinsettia {My Big One} are OK... I'll see what I can find in the Garden Centure and I WILL start Feeding Weekly
I'm Still watering with rain water...

On the website in our tech help pages you can find a nice diagnostic key that will help you in reviewing symptoms you see on the crop and finding the potential causes associated with those problems. In particular, nutrient related disorders are all very characteristic in how they show symptoms, helping growers come to good conclusions on how to respond and correct. I encourage you to try out this key as it has been very helpful to many growers. Jack Williams