You really need to pot them up, they are a bit small to leave out of soil and let them start getting a root system, then when the weather permits you can transplant them into the ground.
Bananas are pretty forgiving as to the soil, you have sandy soil which is great for fast drainage, the biggest things you need to remember is that bananas are heavy feeders, ( I would feed them every week) and they need lots of water. If they are going into full sun you may have to water them a couple times a day. Before planting you may want to completly water the area and time how long it takes the water to absorb, that will give you a good idea on how much water your plants are going to need.
I would plant them a couple of feet apart. I dont know how cold it gets in the winter in Portugal, but you may have to dig them up in winter and store them..... but that is another post.

Thank you shiollie for that very useful information.
1)Can I just put the base in shallow water not covering the pups or a damp cloth or should it be a pot with good compost for 3 to 4 wks until I fly with them to Portugal? (they were cut from the mother plant 10 days ago.
I would have to take them out of pots again to fly them with me.
There is usually no frost in southern Portugal, I am on the clifftop there but I have a sunny place I can put them surrounded by walls from the wind.
2)What will I put around the base to mulch them?
Would my Bermuda grass cuttings be alright?

wendydarcy, it would be helpful if you could tell me the zone you are in now, altho it does occur to me that you may have a chance to buy banana plants in Portugal,
Given the info that you have.. it is going to be hard on the baby nanners and I cannot guess if they would survive.

Thank you for your help and interest.
How do I find out the zone?
I live at present in Ireland, same weather as UK England but up in the Wicklow hills just South of Dublin; so it is a bit cooler. If we have any snow a little usually falls in March but only a few inches and goes within a week.
I have them on the bathroom floor at present on newspapers and thought since the house is pretty warm I might put one in a big pot then outside for the summer.
I plan to fly the other two smaller ones, which will fit into a suitcase, to Southern Portugal where I have a house, it is much warmer there and can get very hot but not humid. We never have any frost where I am there.
Two have two small pups about the size of a very small orange.The third has been cut with a good hunk out of the parent.
One pup is showing a 1" green spike in the 10 days we have been back from the Bahamas where I was given them.
They were very mushy and hot after the long journey back here but have dried out since and I can see a small green center to all of them(but a bit black at the tip)where they have been cut off
Should I cut this very small(half inch black off)?
The stems are quite solid.
One more question you may be able to answer,since I have been reading a lot of the forums is:-
As the bananas are growing, it seems they have purple pendulous type flower hanging at the bottom of the hand. Am I correct in thinking this is the male flower and should it be cut off and at what stage, if at all.
I also read that you can eat that.
Wendy