Speed up the Growth Cycle -Vegetative Growth

 Leave lights on 24/7 for first 2-4 weeks
 Make sure plants are not limited in CO2
 Make sure plants are not limited in H2O
 Make sure plants do not have too much H20

In my first post about speeding up the growth cycle I mentioned that having the roots too warm may slow plant growth, or in my case may have dried out the soil which also will slow growth. I have written articles about limiting factors  and how they control plant growth. In a nut shell after you get the seed to germinate you want to make sure you give your plants the optimal amount of everything for maximum growth which will speed up the grow cycle. The big mistake of rookies is not knowing --> You must NEVER give a plant too much of anything; this will slow growth and extend the length of the growth cycle.  see my experiment to test this at the end of this post

You should always use a root warmer but if you start plants in the starter plugs or in soil in a pot you may cut off a couple days vs. using a paper towel. I say this becasue with a paper towel you may damage the tender young roots as you transplant the seedling into your medium.

The FIRST thing to do to speed up the growth cycle for the seedlings is to leave the lights on 24 /7 for the first few weeks. Leaving the light on 24/7 can cut another week off the time until your plants are done. As I mentioned in a previous post, light is the energy source for plants so the more light a plant gets the more energy it has and the faster and bigger it can grow.
For the NEXT STEP know that plants need a lot of carbon dioxide (CO2). TO help plants get all the CO2 they need you should provide a light fan to help move the air around the plants. Plants take in CO2 in pores called stomata on the leaves. Indoors where there is no wind, plants will form a microclimate around their leaves where there is a deficiency of CO2. A light breeze will move this deficient air providing plants with more CO2. For the more serious or advanced grower you can really speed up growth and yield by adding CO2.   If you have CO2 enrichment I know it is often used during flowering/fruit set; it will also increase the growth rate of vegetative plants so if you have it use it in all stages of growth.

EVENTUALLY YOU MUST TURN THE LIGHT OFF! I sometimes keep plants under 24/7 light on for more than a month. Some plants grow longer than others but eventually all plants STOP growing and the leaves start to lose its rigidity, get a paler green and some yellow. After a night or two with darkness of 6+ hours they are cured. Plants eventually need a dark cycle to keep their normal physiological mechanisms in synch. You may want to experiment, I always suggest 6 hours of darkness, but some plants might only need 4. The more light you give your plants the faster their growth rate, as long as they get their daily required “night”.  Remember, if you stress out your plants by not giving them darkness after a few weeks you are ADDING time to the growth cycle.  Use a timer so that you have a consistant light on off schedule.  If the time the light goes on and off is not consistent you could stress out your plants and slow growth

You can also speed up flowering in outdoor plants too.


I mentioned in a previous post about nutrients and starter plugs, if you are not growing in soil, you should be giving most plants an all purpose fertilizer high in nitrogen like grow big. You may be tempted to add more fertilizer than recommended, but be careful, I have tested and found that if you add too much fertilizer you get slower growth, ADDING time to the growth cycle. I gave seedlings of sunflowers double the recommended fertilizer and others no fertilizer; both were grown in potting soil (see picture above). Plants that had the fertilizer were all significantly shorter, and some fertilizer groups had significantly lower biomass compared to non- fertilized plants. More importantly, no group of plants that had double fertilizer was bigger in height or biomass than ANY non-fertilized group. If you give your plants too much fertilizer you create a soil that is hypertonic. This means that the plants will have a difficult time pulling water from the soil. Water is the third and final input for photosynthesis. If plants have reduced amounts of water they will have reduced growth. See my post on watering.

I always welcome hearing about other ways people have shortened the growth cycle by speeding up plant growth or any E-mail in general. Thanks and Happy New Year.

Good Growing,
Dr. E.R. Myers

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