My babies at about three weeks. some questions,,,,,

Will a once a day watering keep these 4x4 cubes properly watered until flowering time?

I found rockwool to retain water pretty well. I see you have rooter cubes in there, good job. I water them on a drip system and ran my pumps for 30 min twice a day and watered one corner. That works ok. The best is to do that while they are in the cup and then when you put them in hydroton water the roots not the cube anymore.​

Will they be ok in these 4x4 cubes until I move them into the hydo buckets (at about 18" high)

They will live but not grow to there maximum potential. The roots pop out the bottom and die. By the time you plant them the roots pretty much give up on growing. What works for me is a small like 3 1/2 in round cup. add about an inch of hydroton and cut back the cornners of the rockwool cube. set it in there and then when you go to plant you have a root ball that will start right away.

Also will the cube hold too much water at three a day watering with the hydro?

Three times a day wont let it dry out enough. Remember roots like humidity.

You should check out my cabinet grow journal. I am on my 4th round and learned a lot.
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