Roystonea regia - Royal Palms at San Diego Zoo

I think these are half hardy here?

No Dotty,they are strictly z10b plants. They look pretty good- a bit winter yellows. Pretty much the standard for California tropical's right about now.

Dottydaisy2:

It's a tropical palm. Royal Palms are very tender to cool weather (even without frost). The can't take cold weather at all. They rot very quickly in cool wet soil.

Stan,

They typically are very green here in San Diego all year. They love fertilizer.

Many Queen palms are yellow here because of the rains from the beginning of January. It's another palm that need a lot of fertilizer to look super green.

Obviously getting them mixed up with another palm, thanks for the info both.....

Yes, this palm is native to Cuba. It's called the Cuban Royal Palm.

Planted in too cool and shaded a spot in San Diego, they can rot and even die.

Certainly not one for here then.....

They love heat and humidity in full sun.

There's many Royal palms in San Diego...they just need full sun.

Heat and humidity is the last thing they are likely to get here.....?lol

Yes, I would guess it would need a heated greenhouse there. The only problem is that it grows so very quickly. It would outgrow the greenhouse in a few years.

These trees were planted in 2003, they were very small trees with just barely a trunk. Now they're almost 50' (15m) tall.

San Francisco's greenhouse Victorian style Conservative of Flowers planted one in the tall center dome area..a Royal grew maybe 2' of trunk and then began to "pencil neck" a fatal palm etiolation. It got too thin in the crownshaft base and died,

I've been to that greenhouse in San Francisco many times. I don't remember the royal palm. Although, it's been quite a long time since my last visit there.

I'm wondering if it wasn't enough full sun or light that caused the tree to pencil-neck? I know that area of San Francisco is very cloudy a lot of the time.

Or did it happen in Dec of 1995 when the whole greenhouse was severely damaged by the strongest recorded storm to hit the SF Bay Area? I remember all the glass was blown out by the almost 100 mph wind gusts. It was the same storm that caused all the severe damage at Strybing Arboretum. I'll never forget that storm!

Not enough light. The glass also filters uv enough to effect health I bet.
It was planted after the rebuild. The center dome has those twin 100 year old 30' Philodendrons. P. gigantia I think it is,and P.selloum grown to enormous size. They also planted a ring around the inside with some palms and tropical fruit tree's.
I can see where it was like a perpetual dark cloudy day in the shade for the Royal even if always warm.

Yes, I think it the UV glass protection could cause the royal palm to have problems. You have to remember these trees grow in very hot, sunny climates which are not protected from UV.