Tried taking pictures, too much sun glare, picked up a too heavy pot - not my strobus, wrenched my back, so now I am sitting at the computer, with my lumbar pillow, waiting for the spasms to stop. So - its a good time to type a little.
Great things about Pinus strobus
1.) they are hardy into zone 3. My strobus are wintered by setting them on the ground, under the bench and then covering the bench with a tarp. No added protection from cold temperatures needed. My trees have survived real temperatures of -17 F without missing a beat. This is not a trivial matter - having trees able to survive the worst your weather can throw at it is a strong point in their favor.
2.) The roots survive being water logged without rotting for extended periods of time. (a month or two) We get wet spells now and then, though not every year, some of my more mountain origin pines have showed problems when we have a long wet rainy spring. For JWP I have to use a moderately coarse all inorganic media or the roots rot away on me in wet years. This year we had a stretch where it rained 5 out of 7 days a week for a couple months. This ability to survive water logging also means the strobus are much more forgiving of heavy, organic soil mixes. They will even tolerate conventional potting soil if you don't over water them. So even if your climate has less rain, this trait is a big advantage to using P. strobus.
3.) they have a unique look, the long soft needles seem to invite the viewer to 'pet' the tree. I often see visitors to my yard fondling the soft foliage of my strobus. This type of foliage should be planned for when creating a bonsai. Strobus will never look like a JWP in bonsai culture. But if you plan a graceful, almost willow like style for your strobus, you can really take advantage of the tree's natural characteristics.
4.) Strobus is more shade tolerant than any other pine commonly used for bonsai. It may be the most shade tolerant pine in cultivation, but on this I am not certain. It certainly does well in bright shade or dappled shade. In nature they can be found in very shady locations, usually as immature looking saplings, in the forest, waiting for a tree to fall and open a hole in the canopy. You never see mature looking strobus in deep shade, but often saplings are found in deep shade. In cultivation you won't loose branches due to shading out by higher up branches right away, you have time to 'sort the tree out'. This trait also allows people with shady gardens to grow a pine, where most pines would fail within a few years. If you have as little as a couple hours of direct sun, they should survive. Growth in shade is leggy, and soft, but the tree will persist. This is another plus, my garden has few full sun spots available. My strobus get less than 6 hours of direct sun a day and are growing satisfactorily for the species.
5.) they are as easy to wire as any other pine, often easier, as the needles tend to be at the ends of branches, so wiring is simple, the branches stay flexible for many years. They will hold a shape if the wire is left on long enough, it is simply a matter of re-wiring if they spring back when you remove the wire. Radical bends are tolerated well.
Down sides to Strobus as bonsai
these have been listed often by others, and are all largely true. One of the worst down sides is that it is almost impossible to get them to look like miniature versions of a 100 year old strobus in nature. Because of the long soft foliage, that is difficult to get the needles to reduce with, getting those nice horizontal branches with foliage arranged like a mature tree is really difficult. My oldest tree is one I set out to do the "Strobus in miniature" look, and I still view it as a failure in reaching that goal after 20 years.
The trunk stays smooth for the first 30 or 40 years of the tree's life. Getting the wonderful nearly black alligator checked bark of a mature 80+yr old tree in the wild just doesn't happen in a pot, without a similar amount of time passing while the tree is in a pot.
I could go on but others have covered the negatives well. I think it is essential to think about the lacy needles, and plan for and take advantage of them in the design. If you do that, you can create a great bonsai with P. strobus.
Here is my photo of a P. strobus, I believe originally collected by Marty Schmallenburg or Jim Doyle, styled by Jim Doyle, maybe tweaked or restyled by Walter Pall and then eventually donated by Jim Doyle to the permanent collection of the Chicago Botanic Garden. It is about 4 feet tall and is one of the few 'really good' bonsai I have seen done with P. strobus. The design does use the lacy needles to its advantage. If this trunk had short needles like a JWP it would look strange.
Thats how I read this the first time and thought, 'Oh, there's a pine I haven't seen'. Laughed so hard I had to share.
