Hello Mike, when you say the first 2 to 3 months at a north facing window, what months were those? Were those during the winter or cooler months? At times, houseplants naturally slow down in its activity during the cool months, with the duration of natural light weak, and north facing window at that. As they slow down their growth, got to adjust and lessen watering regimen too. When the warmer months return and you see more active leaf growth, then you can go back to a more stepped up watering, though water with care, these plants are quite drought tolerant once established.
I grow my Scheffleras outdoors here in a container year round, by a south/south west direction, but it does get some good shade during our hottest time of the day from our city trees. Our humidity here is dismal, and we hardly get rains here from late April to late Oct, so I try to do my watering during early part of the day, before the sun hits the plants, or in late afternoon, since sunlight is longer and overnights are warmer. My plants outdoors endures our high 90's to triple digit temps, so if I know our temps will go high and dry like that, I do thorough watering of the plant, not everyday but at times twice a week. Once temps go back to the more amiable low 80's then I can go back to once a week watering. I also try to spritz the branches of the plant, it is so quick to dry anyways here, and it seems the plants like it. If my humidity is good, I would not need to do it, like during our mild winter when our rains arrive, but during the long dry days, it helps the plant.
So for your plant, grow them indoors during your colder days, and try to give it a summer growing period outdoors, doing it gradually so it can acclimate and transition nicely. Adjust watering as season changes. This plant does not like to be in too soggy conditions.
