Hi. I live north of Toronto. I have overwintered geraniums for the 1st time and unsure what to do with them now that I have brought them into filtered light (to start). I cut them back to 1/2 the size of the original plant in the fall. Do I cut them back even further now? Do I remove the white spindly growth? or do I leave the plants as is? Thanks.
I’m not entirely clear how you stored your geraniums over the winter but it sounds like you kept them in the dark and have noticed that they are now starting to sprout and grow.
Usually if you are overwintering your geraniums there are a couple methods of doing so. One way is to keep them in a dormant state (cool, dark conditions) until March or April and then pot them up and place them in a sunny window. Alternatively you treat them as houseplants by keeping them in their original containers and continue to give them as much light and moisture as is required to keep them healthy through the winter. They might even bloom indoors. Another method is to take cutting in the fall and grow those on through the winter. You can read more about overwintering on another page of our website https://www.torontomastergardeners.ca/index.php/askagardener/wintering-geraniums/ where you will also find links to several external websites as well.
Since the plants you have seem to no longer be dormant but are growing (the white growth is due to lack of light), you should continue to introduce them to more and more light as the days go by. The white parts should turn green as the plant uses the light you are giving it to produce chlorophyll. As the natural light gets strong as we move into spring, the geranium should begin to branch out as well. If it doesn’t, you can pinch out the tips of the stems to encourage this. As they begin to produce new green growth you can also begin to fertilize them as well.