If my math is right, 15C is 59f? Coconut palms can take temps down to 32f (or 0c) if its a short duration. When that happens they will be damaged. Many have recovered from temps much below that, down to 28f ( or -2.22C), but are severely damaged. That is if your climate rebounds back to normal fairly quick like Florida. I would protect them when temps are near freezing.
It doesn't have to be freezing temps that will kill the coconut palm. It can be long durations of cool weather, much like the weather California has during winter. Many places in California where it doesn't get frost and temps are usually above 40f (4.44C), they often die. There are few coconut palms that are trunking in california, but they are lucky enough to be in a warm micro-climate. Ex: Newport Beach coco.
I would say that as long as your lows on average stay above 45f (7.22C), and your day time highs are around 70f (21.11C) then they should survive a winter there. My climate has been cooler than average, with lows being from 50f-58f most of the time this summer when they should be 60f-68f. My climate is a dry hot summer, wet mild winter. Your climate would match a warmer Los Angeles,CA than mine, but they are somewhat alike. I don't know what a coconut palm would look like in your climate, but I can show you what one might look like if our climates are alike. That is if you would like to see a pic.

I say go for it and try it! I bet your find they will grow there :) Good luck and keep us updated!

I'm not sure of your location exactly on Maderia island, but coconuts can be grown in Funchal, so that should help you out a bit.

Also, no, dwarfs aren't hardier. Your main problem would be with the prolonged cool temps rather than the cold temps, and coconuts from altitude in Hawaii would probably do best. If you can't find one of those, just try to find a tall type

Thanks for all info, great news .yes, would love to see a picture! Would give me an idea of what to expect.

If Funchal ok, then Calheta should cope. Is South California temp the same as Madeira?
Are they fast growers?

If you want a coconut palm to grow well, you will want warmer day time temps than california and more humid days as well. Summer temps in Los Angeles, California average around 29C (84F-85F) during the day and about 18C-19C at night (about 64F-65F) but winter temps are typically around 20C (68F) during the day and 9C (48F) at night. But it can get to 30C (90F) anytime of the year. Summers can be very cool in LA. This year summer temperatures were only around 20C (or low 70sF) during the day and a coconut palm will HATE that.

Coconut palms need a few things....
-Humidity
-A climate that will not go below more than 2 or 3 times a year and never below 30F except in the coldest years.
-A climate with winter temperatures in the 70sF or warmer are best and little rainfall during the coldest times of the year-if it gets cool outside
-If its going to be hot outside, they need water. They can handle periods of drought very well, but must at the very least stay humid.
-They also need sun. Dont plant them in shade since they do like the sun and naturally grow in almost full sun (but can tolerate shade well in climates that are truly tropical).

Coconut palms are far from widespread anywhere in California because of the dry weather, cool winters, and cool nights during the summer (as well as the potential for very cool days even in the summer). California also can get very hot and even reach the triple digits temperatures Fahrenheit right up to the coast. But there are some (very very few) coconut palms in California that do pretty well and have been there for many years (the one on Newport Beach is one I know of). So even in a dry climate, you can grow these palms, but they wont do as well and will not fruit unless conditions are right.

Coconut palms are very fast growers if they are in a good climate. Mine goes inside for the winter which it doesnt like too much, but is still probably my fastest growing palm since the summers here are warm and usually very humid. The one Im thinking of in california is, I believe, around 20 years old and is MUCH smaller than a 20 year old coconut palm usually is because it doesnt grow in the cooler weather.

Hope you dont mind reading through this long follow-up!!!
-Alex

Heres some pics of my oldest coconut palm. Its not very big yet,its a little over 2 years old.

It might not be what you were expecting,but it is growing in a very dry climate with cool night time temps and summer that have many days above 100f (37.77C. I am going to get a better camera soon, if you were to see my palm in person it would look much better! I have had people ask me how much I wanted to sell it for:) lol

Good luck! Hope it grows well for you:)

Yes it will take it; what you need to think about are weather patterns and the time of the year. We can keep our coconuts outside in less than ideal conditions with much more confidence this time of year than in the spring (relative to where you are). Yesterday it hit 89 which was the first + 80 day in two weeks and only the 3rd since August. by Saturday night there is not a night in the 10 day forecast that doen not fall in the 40s. I will not leave my coconuts outside in those nights. The days are supposed to be in the mid 60s and sunny. for as long as I can (weekends) I will take them out for full sun during the days. My smaller coconut is being Fed-exd to my buddy in West Palm. For now I am enjoying seeing it get one last burst of Michigan summer give it a push. Pretty much all of my other palms are coming in for the next 6.5 months.

Will buy a larger one and hope that a bigger one stands a better chance. Also am trying Areca Betal nut and Adonida (christmas palm), these are the three palms most differcult i think.
A nice photo of your Coconut, wonder should i get the dwarf type? Might try the traveler palm.

Will buy a larger one and hope that a bigger one stands a better chance. Also am trying Areca Betal nut and Adonida (christmas palm), these are the three palms most differcult i think.
A nice photo of your Coconut, wonder should i get the dwarf type? Might try the traveler palm.

Sorry for repeat answer, iPhone playing up abit.

What feed is best for Coconut? Do they like sandy soil best? And exactly how many different types of Coconut are there? Are they all the same needs? Should they always be sheltered from winds ?

Gary-
There are various dwarfs (red, green, and yellow) along with talls. Technically and scientifically they are the same but they do have different traits. Talls tend to push up fewer fronds (as juveniles) but they are bigger. Sand in the soils does help. They like well draining soil. One of the main keys to remember is that coconuts LOVE water when it is warm. When its getting in the 80s + and only falling into the mid 60s - high 70s you basically can't give them too much. Conversly if it is cool you want to give them very little water or you risk root rot. For example here we had a two week stretch where the average was maybe 71-51 and with the exception of some rain here and there i did not water them at all. 65 and sunny is fine but if you have several days only in the 60s for highs and it is reaining a lot it''s time to bring them in.

If you placed a Coconut on the beach, would it grow? Or are there other factors involved?