There are more in the grow beds but almost impossible to get good photos while in the ground with leaves all over.
Others have been sold. 20-24 and 25 shown above are the only ones with more than 2 trunks left this time.
These are grown with seedlings threaded though separate holes in the plate but reasonably close together. I guess 7 or 8 holes spread over 1 1/2" The white dots in the image showing under the roots are where the original stems have been cut below the plate. I can't find any photos of multi seedlings through the holes at the start.
Here are some older photos showing the plate with holes and stems after chopping.
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And some more clumps done this way from previous years. All sold on now.
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Not every attempt works out well. There's a tendency for the outer trees to get roots out over the plate first and then grow faster than the inner trunks which is the opposite to what actually looks good. Luck or judicious pruning is needed to get consistently good results.
The first summer is the critical time for tridents planted through plates like this. The trunks grow enough to start girdling by around mid summer so new roots really need to make it out and over the plates without getting too dry. I keep these in boxes in the nursery for the first summer so they get consistent water while the new roots get started.
At 1 year, in winter they all get unpotted and the new lateral roots growing above the plates are cut back to the edge of the metal plates. That helps slow stronger ones and allow weaker roots to catch up.
They then go in the ground for a year or 2. Dug every winter, root pruned and chopped down to control relative sizes and strength of individual trunks then planted back in the grow beds. Occasionally they spend a 3rd year in the ground but usually 2 is enough to get trunks to a good size as shown.