When Karmala Harris said, ‘Americas promise will always burn bright,’ it reminded me of how bright light always lifts us up both figuratively and physically in the case of plants.  

This was not the only prompt that made me think about the topic of light this week. I had my first cataract surgery and to progress from a blurry haze of shapes to crystal clear images over a period of 48 hours is truly miraculous. My computer screen now appears nicotine stained when viewed from the unoperated eye, (It is not I hasten to add.), by comparison to the white appearance from my new lens.

Plants are phototropic and react to the light received by their photoreceptors. They may grow towards or away from the light depending on their needs. Some plants are dependent on photoperiodism, set hours of light to develop their flower buds. Plants use photosynthesis to manufacture their food. As humans react to stimuli with their emotions, plants react with tropisms.

Chrysanthemums, Poinsettias Euphorbia pulcherrima and Christmas Cactus, Schlumbergera are all photoperiodic plants requiring certain day lengths to set buds. Those that require hours below a certain threshold are known as short day plants and those that require hours above a certain threshold are known as long day plants. As with humans, plants react to circadian rhythms. If your Christmas Cactus does not bloom for example, it is probably because you have it in a living room where the lights are on in the evening providing it with too much light. Schlumbergera needs the long periods of darkness, provided by nature to set buds. Put it in a south facing bedroom where the light levels follow a natural pattern and watch as it starts to develop those long awaited Christmas or Thanksgiving flower buds. Poinsettias are notoriously difficult to get to bloom again as they require complete darkness for 14 continuous hours each night  combined with six to eight hours of bright sunlight each day for a period of time to set buds. If you kept your Poinsettia from last year, this can achieved by placing the plant in a dark room at night or placing a box over it starting at the beginning of October.

Long day plants include most of our summer flowering perennials . Some plants are known as day neutral and include tomatoes, corn and cucumbers.