Barb. Good experiment! Here is what I see happening: Very little difference in growth between the 2. The warmer one will grow slightly faster, perhaps putting on an extra leaf. My reasoning is that plants from arid regions are genetically programmed to grow slowly, and fertilizer has little effect... Hope I am wrong and the warm one puts out 4 leaves for every one the cold guy does!

cool test Barb. I'll bet the heated palm will grow much more but will become 'leggy' and when you place it outside in spring the 'leggy' leaves will damage.

Barb,
I'm also excited by this experiment.
I really like Brahea. I think of it as an "almost" hardy palm, like Washy but a lot cooler. 8)
All of mine are in pots in the heated palm hut. Yes, I dug up the one I foolishly planted last April in poorly draining soil. 😳

As to the research question, I'm very curious. I also let my temperate-climate palms have a cool period each winter but have no idea whether there is any basis for that. I'd like to make a prediction, but I really don't have one--just curiosity.
--Erik

cool test Barb. I'll bet the heated palm will grow much more but will become 'leggy' and when you place it outside in spring the 'leggy' leaves will damage.

I agree with the above.

Barb, the coffe grounds can make the soil acidic. I don't know if that is what you want?

I hadn't thought about that.
Do you all measure soil pH? If so, how?

my guess is that the palm kept warmer will have a much bigger and healthier root system and in the long term (beyond two years) will be a much bigger palm. I base this on my experience with sabal minors that I kept inside in a well lit basement bedroom versus 2 that were kept in an unheated garage with fluorescent lighting. the garage is attached to the house and may see low temps down in the low 30'sF. Interesting experiment and keep up your good work.

I hadn't thought about that.
Do you all measure soil pH? If so, how?

It is very easy, they come in paper strips, get them at a garden center.

I'll do that.
I got a "rapitest" soil pH metre but it reports 7 for everything, so I gave up.

Well, ever since I heard palms "don't go dormant", I've been wondering.
Palms have no cambium layer (with sap up in summer and down in winter), so do they REALLY need a rest?

Year-round growth would need more resources for a palm both indoors and out...fertilizer, water.
But with no limitation from cold or light, a palm should/might respond...albeit maybe not a Brahea.
It might even be easier for the palm, rather than struggling with its typical cold winter conditions.

Thanks for all the comments.
A couple of points:

leggy: from full-spectrum? Agree it's a poor substitute for 18 hrs of "real" daylight. I'll expect sunburn on the "warm" palm next summer.

coffee grounds: I worried it would lower the pH so I purposely put only a bit around the stem (versus my 5-foot grapefruit tree in a 50 gallon pot, which has two inches of coffee grounds as top-dressing, it loves a 5.5 pH). This Brahea was near the sabal palmetto that had soft scale, don't want to take any chance an ant deposited a scale egg or two in the soil. Anything that wants to crawl up the stem has to cross the coffee grounds. 😈

Appreciate everyone's input.

Will do pics every couple of weeks (or more often if I get REALLLLLLLY bored this winter).
Barb

Erik, even years ago I heard that the U.S. had "county extension agents" for farmers to avail themselves of state services, i.e. soil testing, etc.
And I was jealous it was free. We Canadians pay between $50 and $75 for a proper soil test...includes all sorts of stuff with agent's recommendations, i.e. if Calcium is too high, Boron miniscule (usually). Lots of crops/plants need trace elements, and those are listed as well as deficiencies, with "normal ranges" stated on a graph.

We do a soil test every 5 or so years, pH steadily decreases (albeit slowly) with continued use of synthetic fertilizers. Sprinkling dolomite lime sweetens it up again easily.
Barb

Status 11 days later:

"Cold" Brahea in cold building (40F) (BRRRRR!) Good way to flatten clover!
Its little spear is very blue, but not pushing.
No sign of the small soft-bodied scale infection of last summer.
<img src=" " width="500" height="375" alt="DSC04211" />

"Warm" Brahea, looking less blue than its twin, but opening short frond. Full spectrum lights are a poor replacement for sun.
Have kept up treatments of hydrogen peroxide/Q tip (also rubbing alcohol on Q tip) as soft-bodied scale appears to think it's summer.
Need to keep on top of the scale problem as 20+ juvenile Foxtails are adjacent. Working so far I think.
<img src=" " width="500" height="375" alt="DSC04213" />

I even relocated a few ladybugs that were hanging around on south windows throughout the house.
<img src=" " width="500" height="375" alt="DSC04148" />

Barb

Thanks for the update!

keep us updated!!

cold building is 8C 46F.
Brahea didn't look good, leaves folded, must be too dry, so it received a light watering.

<img src=" " width="375" height="500" alt="DSC04330" />

Brahea twin in warm basement:

<img src=" " width="500" height="375" alt="DSC04344" />

I'm disappointed the petiole isn't longer in the warm basement Brahea.

Next update: mid February.