Because of their cold hardyness, I would like to give one or a couple satsuma varieties a try for in ground planting. But I'm not very familiar with satsumas and don't know which are the most interesting ones. My favourite nursery offers the following varieties:

Citrus unshiu 'Clausellina'
Citrus unshiu 'Hashimoto'
Citrus unshiu 'Miyagawa'
Citrus unshiu 'Okitsu'
Citrus unshiu 'Owari'
Citrus unshiu 'Pucheng'
Citrus unshiu 'Saïgon'
Citrus unshiu 'Sugiyama'
Citrus unshiu 'Wase'
Citrus unshiu 'Variegata'

If you were to pick a maximum of three, which would they be?
Thanks in advance!

Citrus unshiu 'Wase'
should be cold hardy but i don´t think they will grow in Belgium. But if you try i would realy like to hear more about your result.

I was thinking of giving some extra protection during the winter period, using a plant cover. Would that be OK?

I have an unprotected citrumelo outside in ground now. It looks like it has managed through the first real freeze period well, going down to -10°C (14°F) or maybe even lower near ground level. Only the young shoots/leaves are damaged by the freeze but the rest of the plant looks OK...

Citrus unshiu 'Hashimoto'
Citrus unshiu 'Miyagawa'
Citrus unshiu 'Okitsu'

Very early and slow growing.

VERY Slow growing. - Millet (763-)

MarcV,
Why limit yourself to one nursery?
You have enough time till spring to do research and planing.
Talk with people in nursery, obtain info about source i.e. 'manufacturer' and then call them. Post collected information here and keep discussion live so that forum experts can further refine that.
Something for you to start, Calendar of ripening and harvest dates for some Unshiu varietes:

Data collected 2001.y from groves nearby Split Airport and islands: Vis, Brač.
Legend/Dictionary:
Rujan == September, ..., Prosinac == December
Grove location is listed in the 1st column bellow the name of variety.

I have similar idea but realisation is postponed untill Dr. Gatin finish his book with mandarins being the main subject.
No reasons to hurry, after planting you'll have to wait 5 years to taste beauty of those. Meanwhile trees will award you with every new crop tasting better.

Well, I think my preferred nursery has enough choices already!

I think I should go for the early varieties as the warm season probably doesn't last long enough here.

And then there is of course the taste of the fruit. I don't need a super sweet fruit. I prefer a taste that many people usually find a bit too tart.

Ask

I think my choice will be the Miyagawa variety, which is supposed to be early ripening, relatively large fruit, juicy and not too sweet.