Your lovely plant is known by its trade designation Plectranthus MONA LAVENDER or as the cultivar Plectranthus 'Plepalila'. The flowering stress, leggy-ness and faded leaf tips all suggest that your Plectranthus needs a few adjustments so that it has the strength it needs to grow well. The north-facing window is not quite enough sunlight to keep this plant vigorous. An east-facing window with at least 4 hours of direct (sun is visible in the sky from the position of the plant) is about the minimum it will need. It is a South African plant in the mint family and needs a warm setting too, around 60 to 70º F.

Keep the soil moist and do not let the root ball ever dry out. Be sure that you remove the plant from its decorative container when you water it, bring the interior pot with the drain holes in the bottom to the sink, let it drain completely in the sink, and then replace it in the container so that it never stands in run-off water.  The loss of lower leaves is typical when the roots are getting too dry between waterings so keep the potting mix moist.

You can pinch out growing tips regularly during the growing season to keep the plant full, but these plants do get sparser as they age. A mature plant will not retain the look of the young plant that you purchased.

In the winter, your plant needs to have a rest to restore its strength for the next growing season. At that point, stop feeding it for several months and move the plant to a cooler room that stays between 55 and 60º F. With limited winter light and lower temperature, it will need less water, keeping it just damp.

Courtesy of NYBG Plant Information Service