I had a very bad experience field growing Chinese junipers in the north-east of France, friends were successfully growing them in the ground around Nice. I gave up after 3 years of marginal growth with close to no development and some branch loss. My itoigawa are now back in culture pots. I believe they do prefer having their roots warm. I had no serious issues with procumbens juniper in the past, so it is going to depend on which type of juniper you are growing.
The maples I have in the ground do thrive and grow like weeds.
Absolutely work on the nebari before putting the tree in the ground or you will waste years down the line trying to fix or replace it.
If you wire the trunks on field-grown material you will need to check them very often as the trunk will thicken faster and that may leave ugly scars.
If you want a gnarly juniper mame/shohin from cutting, you start by wiring the cutting and giving it exaggerated curves, you wire it again the next year to give counter-curves or compress, then you can start adding a shari that will enhance the curves. If you do successive/close tight curves on the trunk, the first one needs to start at soil level otherwise you will get reverse taper when the trunk fleshes out. Kinbon had an article in Fall 2009 (if I recall) on a simplified process for pines using cable ties to compress the plant after wiring it.
I speak from experience that you have to prune out the bad branches before they get out of hand and you have design and healing mess to deal with. You also have to stay on top of the root pruning. I switched to the grow bags on my latest in-ground trees after hearing the Telperion podcast. Some of the roots on my trees got to be monstrosities before I realized what was happening. Grow bags would’ve prevented it.
Well, what DO you have? I’d be curious to see what trees you have in the UK that would make great bonsai. I always recommend digging what’s already growing in your area.
Just because you didn’t plant it in your field, doesn’t mean someone else isn’t growing it for you. Keep an eye out for people re-doing their landscaping.
I found this thread while doing a search on propagation (specifically regarding the juniper cuttings Ryan did last year)…more on that later.
I was with my teacher recently, and there were some nice junipers, exactly like what you are asking about. They were in grow bags, placed in nursery containers (don’t know if they were grown this way, or only placed in the containers for ease in selling). I was told these were wired while very young, in order to get the twists, and big heavy branches are cut off, periodically, to help create dead wood which, in turn creates shari all the way to the roots.