So after watching the videos, I noticed in the list of videos that Youtube wants you to watch, up came this one:
A full 44 minutes, not as much "pretty scenery'' but in it are clues to cultivation for Bristlecone.
Key, they grow where they do because "nothing else can live there'', in other words, their adaptations to drought and cold make them slow growing. Slow growing means they can not compete with other species, so they are relegated to specific harsh environments.They will grow in milder areas, more favorable areas, but are not successful when other trees compete with them. Even sagebrush can shade the seedlings out.
- full sun is required.
-only found in dolomitic soils, hence alkaline reaction, not acidic. They can grow in neutral to slightly acidic soils, but are adapted to alkaline soils. Means turface and other calcined clay products would work okay. Kanuma & peat moss probably not a good choice. If you include pine bark in your mix, a handful of crushed oyster shell, crushed limestone, or horticultural lime would be a good idea. If your azalea is happy your bristlecone probably won't be. Soil in native range is really just gravel, little or no humus, disease may be a problem in an organic rich soil.
-Lush rapid growth is more susceptible to disease. Considering the white pine blister rust & other diseases, low elevation growing may be more disease prone. The bristlecones survive where they are because most diseases, or the disease vectors (bark beetles, etc.) can not reach them. They probably do not have as robust a disease resistance as say an Eastern white pine (P. strobus), because metabolically, they don't need it.
-even with ample water, growth is relatively slow (hence, can not compete with pinion or limber pines when seedlings sprout together in same area).
-they are a single flush pine, with a very short growing season. Drought sends them into dormancy, won't likely grow again until the following year. Good in that if you miss a day watering the bristlecone has a better chance of surviving than some trees, Bad in that growth is arrested, and may not resume again that year.
General thoughts gleaned from elsewhere:
Really slow growing trees are difficult to use for bonsai. I ran into this playing with super dwarf cultivars of some conifers, for example some of the tiny mugo cultivars & 'Nana' cultivar of Hinoki.
Reason: You need growth to do your styling with. Little or no growth means waiting more years for recovery from anything you do. Bristlecone will grow quicker with water and moderate temperatures, but they still will grow slower than limber pines and pinion pines in the same setting. "growing a branch to fill out here, or regrowing an apex there" will be long term projects, instead of just a season or two. Best styled by using what you have, rather than planning on growth to give you what you need.
I've been experimenting with summer repotting for more of my pines, and I do believe bristlecone will do better with summer repotting - at least in my Midwest zone 5 area. In the Pacific Northwest or other mild climates, this may not apply.
I've killed 3 or 4 bristlecones over the last 20 years, both seedlings and killed a 30 year old nursery tree back in 1990. I do not have any currently, so no ''victims'' to try my thoughts out on. So consider my musings "internet knowledge'' - not actual real world experience.