Stephen, I am not familiar with the climate in Cheshire or whether you have more seasonal type rainfall, but in my climate, I stop watering containers once fall rains become common......like right now :-) If you get routine regular rainfall in fall and winter, then you can stop watering your patio pots. But I would check them periodically throughout any extended dry spells. You do not want the soil to dry too completely but neither do you want it saturated - and a good durable, aerated potting medium will help to avoid that .

There is no issue about the pots being exposed to frosts but you do want to be cautious about freezing weather. The roots of Japanese maples can be fatally damaged at temps below 25F (-3.9C) and that can occur relatively easily with containerized maples that do not have the benefit of the insulating factor of a large soil mass surrounding them.

Plants or seedlings in a protected location will need some monitoring of soil moisture through the winter. Again, you want the soil to be just moist, not completely dry nor too wet.

I can't tell you how to handle the seeds/seedlings through winter, as that is not my area of expertise at all. Hopefully someone who does grow JM's from seed will chime in with their advice.

Thanks for those Sound Pieces of Advice GG

Would Patio Maples be ok placed temporarily in a Garage during a severely cold spell.

Sounds like if Space Permitted all Pots whether Small or Large would ideally be placed directly into the Soil to give the Roots Warmth,Insulation & Protection.I suppose this could end up being a Big Logistical Process if a Grower has some Large Pots.

Would Sacks be of any benefit to place Large Pots in during Frosty & Icy Weather ?

Trees growing in larger pots are much less of a concern. Larger pots = increased soil mass and less chance of freezing.

I think I mentioned it previously but in your climate, I doubt you should have many concerns about excessive cold and your potted maples. Small ones (1G or less) I would protect but anything larger should be OK under most conditions. FWIW, I never offer winter protection for any of my containerized maples and have never lost one to winter cold damage.

Bubble wrap is one of the best insulators for a large container :-) Or group all the containers together in one location and protect with hay bales (you can stuff any voids between pots with fallen leaves). Or you can shift the whole lot to the garage for the entire winter if you like, just to be on the safe side.