I typically plant my seedlings 8 inches apart in rows that are 6 inches apart. I stagger the rows to give them a little extra room. Depending on the number of seeds I start and the percent germination, and along with my goal of about 300 seedlings per year, I generally have 11 rows alternating 29/30 seedlings in a bed that is 20 feet by 12 feet. That gives me room for up to 325 seedlings. I do not suggest 6 foot wide beds to anyone however, and I would not make them that wide today if I were starting again. I am 6' 4" with fairly long arms and can barely reach to the middle rows - 5 feet would have been a wiser choice.
My practice is to select "keeper" seedlings with somewhat loose standards after the their first bloom. Perhaps I lose a few that would get much better on their second-year bloom, but I try to cut down to range of 70-90 second year blooms, and these are seedlings that have been transplanted into a similar size bed, but with somewhere between 12 and 15 plants spaced 16 to 20 inches apart and rows that are 12 inches apart. That accommodates between 72 and 89 seedlings, and if well treated they will need that much space to grow without crowding each other much. It takes a lot of work to do this every year, but I choose to do it this way, so I do the work.
Just so you can see a bigger picture of what is required on down the line, here is my plan for next year. . .
I have 6 beds that are 6 X 20 5 that are 6 X 12 1 that is 5 X 22 1 that has an odd shape but is about 12 X 10
One of the 5X12 beds gets too much shade, so I use it only for plants I am holding to give away.
All of the 6X12 beds get enough afternoon shade that I only use the front 6 to 8 feet for planting.
All of the 'offending' trees belong to a neighbor, so I just have to live with them, and they get bigger every year. Anyway...
bed 1 - 6X20 where I will plant the seedlings that I germinate next March
bed 2 - 6X20 Seedlings first bloomed in 2014 (about 40 plants)
bed 3 - 6X20 where I planted this year's seedlings - first bloom in 2017
bed 4 - 6X20 Seedlings first bloomed in 2013 (about 25 plants)
bed 5 - 6X20 Seedlings first bloomed in 2015 (about 70 plants) 2015 was a bad year, so I have kept more seedlings longer
bed 6 - 6X20 Seedlings first bloomed in 2016 (about 80 plants)
bed 7 - 6X12 Seedlings first bloomed in 2011 (12 plants)
bed 8 - 6X12 Seedlings first bloomed in 2012 (12 plants)
beds 9, 10 and 12 - 6X12 and 6X22 Cultivars for hybridizing
bed 11 6X12 - shady bed - overflow - nothing specific planned
bed 12 odd shape All remaining seedlings 2008, 2009, 2010 (12-15 plants)
Next year is the final decision year for all seedlings 2008-2012 - either (1) keep & register; (2) keep because I like them; or (3) give away/throw away
The more you plant, the more you will like the results, but the more work you will need to do. It is a vicious cycle. Downsizing is difficult! I've been thinking about it for a couple of years, but have not taken any action yet. Maybe next year.
