|Yucca rostrata in my front border with Melianthus major behind it|
The Yucca rostrata you see in the picture is one I got from Dig Nursery on Vashon. Dig is one of my favorite nurseries and I have gotten an amazing number of great plants from them over the years. Anyway, the Yucca rostrata I got from them was a relatively small one--it was in a 5 gal. pot and it had no trunk. I had been under the misapprehension that it would take years and years for it to form a trunk, but, in fact, within 3 years you could see the trunk forming and the plant in the picture with its nice trunk is probably 10 or 12 years later. So the moral of this story is, you don't need to spend a fortune on large yucca rostratas--they will grow at a gratifying rate so you could, if you wanted, start with smaller plants. If, on the other hand, you want instant gratification, a number of nurseries in the Pacific Northwest now carry trunked specimens from time to time. Probably the best nursery I know of for this is Cistus on Sauvie Island.
A number of years ago Sean Hogan, aka the Yucca King, grew some yucca rostatas from seed, and one of his selections from that seed batch is now widely grown as Yucca Rostrata 'Sapphire Skies'. This plant was tissue cultured by Terra Nova for a while and they had some nice specimens in their display garden. It apparently is no longer offered by them, but it is available for purchase from a number of other nurseries which a google search will reveal. In my new garden I intend to search out Sapphire Skies, and that is the Yucca Rostata form I intend to grow. I will want to plant at least three of these in my new garden. If I can't find large trunked specimens at a reasonable price I will happily settle for 5 gal. plants.
In the picture above, you see part of a Yucca linearifolia in the lower left hand corner, another favorite yucca of mine. You can also see an Echium amoenum behind the yucca rostrata. I wrote about that plant here. There is also the green of a Stipa barbata which I recently cut back near the trunk of the yucca. I will have a future post on this grass. Finally, you can see some of the colchicums which I wrote about in my last post.