Our bedding plants are grown almost exclusively in 4" pots. About the only way "paks" could be economical is if you grow them from seed yourself. Paks have pretty much fallen out of favor altogether.

I agree in all three places that I have worked for and the time I owned a wholesale nursery biz even when seeding by hand I do the sale of size 4 inch and up. I feel that only with automation can you even consider trying much for cell packs. I do however buy in a limited amount of 6 pack and 9 pack of veggies and jumbo 6 packs of spring annuals. The money and most of the demand is 4 inch and above.
Happy Growing David

Thanks... I have yet to find anyone around here for me to buy in the smaller sizes.

I have different niches, and a lot of my growing is custom, so I go with what they want. The garden clubs and fund raisers often want cell packs. They sell to gardeners who know what kind of difficulty is involved in something like an impatien or marigold and would be very hesitant about paying a premium price for a four inch pot of a plant they know they could direct sow and grow like a weed, catching up with a potted plant in a matter of weeks.

It used to be my 4" program was for the folks getting in late gardens, landscapers who needed instant gardens, or container work. The box stores have pretty much groomed the newer gardeners to expect to pay for 4" pots from the get-go. They went to potted stock for the shelf life. It's a lot harder to muck up a tray of twelve marigolds in pots than a flat of cell pack with little room for error on watering.

I often grow the same line of plants in two sizes......all planted at the same time. Half of it in cell packs and half in pots. I move the cell packs out first and depend on the potted stuff to hold for later sales. I have less shrinkage that way. When you start to factor in pot prices, bench space, soil, and turn over time, it's sometimes cheaper to produce cell packs even from plugs even without automation because of the shorter finish time.

It depends on what you're growing. In trees, everyone seems to want 'instant forest' and aren't very interested in
anything under 1" calipre. Which is tough for me right now as my oldest trees just went into 3 gallon pots.

For a container based nursery bigger is better.
I buy a 40 cent plug, and put it in a 1 liter styroblock.
Cost: 30 seconds of my time + 30 cents for 1/15 of the block.

After 1 summer: Value $4 -- if I can find a buyer.

That fall: Transplant to a #1 or #2 pot.
Cost: 2 minutes of my time + cleaning time for pot.

1 year later value #1's $6 #2's $12
#1's that don't sell move into #3 or #5 pots.
#2's that don't sell either wait a year, or
move into a #5 or #7 pot.

A #7 pot is a magic number. This is about the limit
for me, I think, to move around without special equipment.
I don't have any problem with the smaller pots. I don't
think I can lift a #10 pot onto a trailer.

But a #7 spruce is about 6 feet high and retails for $150 bucks, which means it wholesales for half that.
Each time it was transplanted, it took a few minutes of time. Each year it gets weeded twice, and mulched twice.
But the increase in the last year is the largest return on my time.

On the otherhand, you have to wait. My trees are teaching me patience.

For garden centres: Your best size will likely be 'instant
garden' Things like hanging baskets, porch sized planters
all preplanted.