Hi Tom. I Just got some Y. Rostrada today (5 gallon) and it got dark before I can put it in the ground. I don't have your dilemma; I am in Az. I feel your need to put it in the ground. These mature plants are absolutey stunning when they reached 6 feet or taller. I have an idea for you. Plant it near a south wall of your house. This should receive the most sun exposure during the winter month and your brick wall should radiate some heat to protect it. You can always erect some temporary shelter and cover it if needed. Good luck.

I've had one growing in my backyard for about 5-6 years (Z-5 Denver). It is nearly 10 feet tall and thriving. We've had a couple of -20 events with no problems. It is situated in direct sun and loves every minute. This originally came in a #20 size pot and cost $350 wholesale. I dug a hole about 3 times the size of the root ball and was careful to ensure it rested on solid soil and planted it about 2-3 inches higher than it was growing in the container. Because of the cost, I placed heating cables around the sides of the planting hole and secured it with landscape pins. I didn't water it once during the first winter and have never had the heating cables on again.

I killed my Rostrata by not watering it enough in the greenhouse. I had been watering it too much, so, I backed off TOO much and killed it :( BUT, my Y Recurvifolia (I may have mispelled that) and my other Yucca that gets a bit of a trunk on it, and I can't think of the name of it, is doing fine. It looks just like the trunkless Yucca that everyone can get anywhere, BUT, over time it gets taller with a trunklike stem of past seasons leaves. If you scroll all the way up to the beginning of this thread and then scroll down and look at the 2nd pic that Sasha has posted above, THAT is what my Yucca is like exactly, the 1 that has a trunk made up of past years leaf growth. It flowered for me this summer too. BTW, Sasha, how is your big palm you bought doing? I hope that it is doing good for you, later everyone:)

They are super strong plants. Mine was attacked by pest this yr. And is in recovery now too. When you have a chance I would switch your soil to a gritty mix. A quick google search will get you the proper mix. I use a custom mix of bark chips, builders sand and pea gravel only because those ingredints are easy to come by.