Many of us grow a wide variety of veggies in 18 gallon totes. Soil temps ARE a consideration, and many of us do give consideration to adopting ways to help keep roots cool.

Al

^ tapla, I'm assuming that if you're going to use a massive 18 gallon tote, you'd have to start in a small 7-8cm pot in the beginning and then progressively pot up into larger and larger pots each time the roots can be seen through the drainage holes in the bottom (indicating it's at the point where it's going to become root bound)?

Otherwise wouldn't it become sour/anaerobic, or is the drainage of the 5:1:1 mix or the gritty mix so good that potting up isn't necessary in the first place?

Lol - I had this conversation on the Houseplants Forum not long ago. Someone suggested that you COULDN'T put a small plant in a big pot because it wouldn't grow until it's roots filled the pot and on and on. Part of the objection was that it would be 'over-potting', but I patiently explained that over-potting was a function of your soil choice, that as the particles making up your soil grew larger and the PWT diminished, you could use larger and larger pots for tiny plants.

I was challenged to produce picture proof, so I posted these pictures:
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which I just happened to have on hand because they were part of the documentation I had from some testing I did for Jeff from the UpsaDaisy company.

It shows very small plants going into very large volumes of soil and what the plants looked like a few weeks later - healthy as can be.

If you consider where the oft parroted advice to only pot up a size at a time originates, you'll find its roots embedded in heavy, peat-based soils. Because those soils retain soo much water, the lower reaches of the container often remain hypoxic for extended periods, producing fermentation and its associated noxious gasses and acting as a breeding ground for anaerobic bacteria that causes root rot and other issues. To minimize the effects of the PWT associated with these soils, smaller soil volumes were required so air could return to the roots to save the day and prevent roots from rotting and the gasses from affecting root growth/function/metabolism.

Obviously, if you could eliminate perched water or reduce it to the point where the entire soil mass was to return to a well-aerated state quickly, pot size wouldn't be a factor. Enter the well aerated soils like the 5:1:1 mix and gritty mix that allow you to plant in large containers with no worry for root issues if you pay a little attention to how you water until the planting is established. With a properly made gritty mix, you can plant the tiniest poppy seed in 100 gallons of soil and never have to worry about root rot, unless you purposely set out to prove that statement wrong and water like a madman twice a day! ;o)

Al