Henna in cold climates?

This will be my first cold winter doing henna - I used to live on the coast where the tempreture never really got down that much. I did a job yesterday and I'm thinking maybe I need to make henna a few days before an event now and maybe the fact I didn't let it sit long enough was my only prob. It was -4deg (I think that's about 25deg in farenheight??) so it wasn't that cold but its still only autumn...so do you Canucks or cold climate northerners have any other tips for cold climate henna? When its powered I'll be taking my hair dryer but its more the stain of the actual henna. Also Anyone noticed that Jamilla summer 2010 is really different than the year before??

The hair dryer also helps the henna to stain. What I do is dry it with the hair dryer and then wrap it in plastic wrap to help trap the body heat. Winter is so dry as well that my henna doesn't last as long unless I am super diligent at moisturizing, so I tell my clients to do that as well.

How is it different? I haven't cracked mine open yet so now I'm curious.

I'm not getting as dark a stain but still using my normal recipie (very similar to your process that you posted) - but I usually just make my mix the day before then use or freeze it so I'm thinking in this cold its just not long enough as summer here is really really hot so overnight was long enough for a good colour.. these extreme temperature changes are challenging me - all summer my paint was all melting now my henna is buggin out on me...

I live in an area that has about 100F difference from summer to winter, with fluctuating humidity that goes from 10% to 98% so I understand, completely.

When it's really cold I do find I have to leave it on longer, or make it further ahead of time than in the summer. Instead of keeping track I just started making it two days in advance, and leaving it in the plastic bag wrapped in a paper towel in the fridge. It seems to be the right amount of time for here.

It could also be the henna. The stain/leaf quality does vary year to year depending on their weather. Perhaps it's that too?