It is one of those days that makes you believe that Spring really is right around the corner.  It's a balmy 32 degrees this morning, which makes for a very sloppy mess on the roads, but you could almost go for a walk with just a light jacket and be very comfortable.

My houseplants are beginning to respond to the noticeably longer days.  We have already gained an hour and 20 minutes of daylight since the shortest day of the year on December 21, for a total of nine hours, 51 minutes and 11 seconds of daylight today.  The short days of Winter, combined with the UV blocking in our window glass (I know, I know -window sales people insist this has no effect on plants, but they aren't gardeners, are they?) keep my more light loving houseplants, especially blooming plants, starved for sun.  Their green is a little less intense, they start to look a little spindly, and their blooming either slows down or stops all together.

A houseplant gardener has three choices to deal with "short day syndrome" in their plants.  They can just live through it, they can move to a sunnier climate in the Winter months, or they can supplement natural lighting with artificial lights - "grow lights".  Light is either cool-spectrum or warm-spectrum.  Cool-spectrum is blue light; warm spectrum is red light.  Most flourescent lights are cool (blue) light spectrum.  Incandescent lights are warm (red) light spectrum, but they are not good for plant lights because they give off too much heat.

 A grow light ideal for indoor plant growth is full spectrum, containing both red and blue spectrums.  The blue light spectrum is necessary for foliar health and growth, while the red light spectrum is necessary to promote blooming.   Plants given only red spectrum will grow tall and spindly and plants given only blue spectrum light will grow short and stocky but will produce few or no flowers. 

So, how much light is enough?  I am always tempted to leave the grow lights on my plants 24 hours a day, seven days a week.  If a little extra light is good for flower production, a lot should create mega blossoms, right?  Well, no.  Because you see, plants are just like people - they need their sleep, too.  A good rule of thumb is to offer your plants 16 hours per day of a full spectrum light and 8 hours of "rest" or darkness.  I put my grow light on a timer so I don't have to remember to turn them on and off.

And the next question is "how close does my light need to be to my plants?"  This is one where you might need to play around a bit because it varies by how much the light reflects, if the light is from one location source or if you use multiple lights from different angles, etc.  A good rule of thumb is to provide the light about 12 to 15 inches from the plant to start and then adjust your light source nearer or further away, depending on what it takes to achieve your desired effect on your plants.

I don't know about you, but I like my houseplants to bloom in the Winter.  In the summer, I have lots of other flowers to look at.  So, I encourage them by using a high efficiency, full spectrum grow light.