Pruning Plant Tops - Plant Hormones and Plant Growth Patterns.

If you read my post on how plants grow, you know that most plants (other than grasses) grow from the top, (specifically in an area called the apical meristem) and I mentioned in this post  some ways this knowledge can help you be a good grower.  There are other ways this knowledge can help with plant growth.  The apical meristem (link to plant growth article) is also where many hormones are created/secreted.  If you cut  off the top of a plant, most of you know the plant will get bushier.  I often do not recommend doing this*, as it stresses the plant to have its apical meristem removed.  Cutting plant tops can be necessary with some growth methods (read my post on the sea of green technique). 
The physiological reason why plants get bushier when the top is cut off or bent is that one of the hormones that will be no longer made by cutting the top of the plant used to prevent the branches from growing, this is termed apical dominance.  Without the plant top, the branches will be grow at an increased rate from their meristem tissue, termed secondary meristems.  This means each branch will elongate, and each branch will secrete more hormones.  In some plants, one of the branches will become ‘dominant’ and suppress growth of the rest of the plants, making the plant start to grow tall again.  Other plants will just become bushy and will have lessgrowth in height.
Good growing,
Dr. E.R. Myers

* I more often recommend bending the top of the plant, this will slow the hormones, and make the plant more bushy (less tall) without the stress of recovering from cutting off the top.  The benefit is that bending  does not result in several days where the plants do not grow because the apical meristem was lost and the growth hormones, are gone.



The Down Side of LED’s

If you have read my blog from the beginning, you know I’ve gone from thinking the best light is an HPS, to using LED’s and loving them.  The intensity of the tri-band and seven-band LED’s from HTGSupply.com have proven to be awesome at growing plants indoors.
No one light is going to be the best for everyone everywhere.  A friend of mine has a detached garage, and I helped him put in a 10x10 grow room in the garage.  The garage gets hot in the summer, and he is thinking about putting in an A/C unit.  I suggested he just grow outdoors in the summer and save electricity.   I also suggested when he wanted to try something different he use LED’s instead of the 1000 W HPS he had.  The plants are growing great.  However, what he’s noticed as the weather gets colder is that the often unwanted heat of the HPS was needed in the grow room.  The HPS was run at night, and keept the grow room in the 60’s on cold nights.  This week he noticed that the room was getting down into the 40’s when it was in the teens.  40’s won’t kill plants, but it can stress them out, and will really slow down growth.  Worst of all, winter is just getting started.  So, if you are in a situation where the heat from an HID is necessary to keep the room warm in the winter, then you may not want to switch to an LED.
Good growing,
Dr. E.R. Myers


Did Day Light Savings Change Your Prefered Light Cycle?

If daylight savings changed your light cycle, and you want to change it back, it is better to have a longer night than a longer day if your plants are flowering.

Click here to read my post on how best to switch your plants after daylight savings

Good Growing,
Dr. E.R. Myers