CFL Lights in a Grow Box, and
Do Plants Create Humidity?
by Fred
(Exeter, N.H. U.S.A)
I am a first time grower and I have a few questions. My grow box is 2'x2'x3' I have a total of 8 26 watt CFL's, 2 65 watt CFL's , with a 14 watt LED grow panel. There is a 4" intake fan (55 cfm) and a 4" outtake fan (55 cfm), and 6 sides of mylar. My first question....is that enough light for 4 tomato plants (my lights are 6500k for veg and 2700k replacement for the flowering phase). Second question, should I use the LED for the vegetative and germination stage? Third question, without any plants in my grow box and all the lights on I have a box temp of 68, a room temp of 64, and humidity at 35% in both. Will the plants create that extra 15% that I need to gain? I understand perfect humidity would be 50%-55%, is this true? Thank you very much!
Answer: Fred- tomatoes and most other garden plants do very well under 40 watts of light per square foot. I use this as a general guideline in just about every garden I set up or give advice on. You mentioned the "footprint" of your grow box is 2' x 2', giving you a garden area of 4 square feet. If you placed all of your CFL's into this space (338 watts total), your box would be lit at 84.5 watts/sq.ft..
With fluorescent lights (including CFL's), the light doesn't penetrate down into the plants very far. So, on one hand, the extra wattage will help the light penetrate down into the plants further, allowing you to grow slightly taller plants and still have them be healthy at the bottom. Instead of having a 12 inch effective growing distance from the lights, you may end up with an 18 or 20 inch effective growing distance from the lights (especially with mylar on all 6 sides of the box).
On the other hand, you have enough light in your grow box to take one of those 26 watt CFL's out and use it to grow your seeds/clones or small plants in the vegetative stage. This is what I would recommend. The vegetative stage requires less light than the flowering stage, but 14 watts will not be enough. As a general rule, I try to stay at 20 watts/sq.ft. or more for the vegetative stage.
One CFL would work well to grow four small plants up to about 8 inches tall from seed or clone. The 14 watt LED can be used for supplemental lighting in the veg area if you like. As always, the plants will benefit most from the light if you surround them with reflective material.
Since your box is only 3 feet high, you will certainly want to start flowering your tomato plants while they are still short....they will continue to grow during flowering. An 8 inch tall plant may end it's life cycle being 16 inches tall! Also, you want to make sure there is enough air movement INSIDE the box....this helps carry away oxygen when the plants exhale and also helps bring fresh CO2 in contact with the leaves for the plants to breathe in.
The ideal humidity is 50%, plus or minus 10%. In general, humidity that is too high is much more of a problem than humidity that is too low.... especially if your humidity level is only a few percent from being in the ideal range. If I were you, I wouldn't worry at all about your humidity level....but to answer your question yes, plants create humidity by exhaling water vapor along with oxygen.
This process is called transpiration- as water vapor exits from the leaves, it creates a little vacuum in the plant tissue, allowing the roots to suck up water (and nutrients). The plants may ADD humidity to your grow box, but if you have your intake and exhaust fans on constantly to control the temperature it will not be enough to raise the humidity level inside the box very much (maybe one percent).
As I said before, don't worry about the humidity level. Much more important to your success will be proper lighting, proper feeding, proper temperature control, and providing your plants a proper dark period when it comes time to force flowering. I hope this helps....Happy Growing!
Comments for CFL Lights in a Grow Box, and
|
||
|
||
|
||
AffordableGarden Design&Setup
Hi everyone, Jason from Jason's Indoor Guide here. When I got started with hydroponic gardening more than 24 years ago, my first garden used rockwool cubes and B.C. Nutrients....and I remember thinking to myself yeah, sure, there may be a lot of advantages to gardening with hydroponics, for example there are very few pest problems, therefore very little pest control, no weeding, no plowing or tilling the soil, no soil testing or having to add things into the garden soil, no watering the garden....but for someone who just wants to grow their own vegetables and have more control over their food supply and the quality of the food that they eat, the cost of constantly having to buy grow media and hydroponic nutrients makes this an expensive hobby for most people...
Epic Nutrient Change
I suppose when you take into consideration how much money you save NOT
having to buy food at the grocery store, it is surely cheaper to grow
your own food hydroponically even with the cost of high quality
nutrients. Nevertheless, I didn't have a whole lot of money to work with
and I needed to make my efforts as affordable and effective as
possible....and in the last 24 years I HAVE learned a thing or two!
As you browse through Jason's Indoor Guide, you will notice all of the
systems that I use personally are homemade systems. As I got 3 or 4
years of experience under my belt, I quickly adopted a preference to
standing water systems and systems that use expanded clay pellets or
lava rock, because the media is re-usable and it eliminates a huge
operating expense. So once a hydroponic system is built, garden
maintenance is minimal- check and adjust the nutrient solution daily,
and to change it completely every 2 weeks....and the biggest operating
cost is the hydroponic nutrients. (and the electric bill, lol)...
Homemade Cloner
And, regarding the cost of the nutrients....I experimented for about 3 years with making different compost teas and nutrient teas, but there is still a lot of expense $$$ associated with making high quality nutrient teas....like kelp meal, liquid seaweed, rock dust, bat guano, un-Sulfured molasses, worm castings. You can eliminate a lot of this expense by becoming an expert at making high-quality colloidal humus compost, and use your properly made compost as the basis of your hydroponic nutrient solution.
Unfortunately, I have been gardening for over 24 years and I have only
just recently mastered this difficult skill....and even then, only
because I happened to find a very easy to follow, high quality technique
and decided to follow the instructions to the letter. I produced more
high quality compost in just one week than I was able to use in a whole
year! If you can master the technique, I highly recommend it. It is one of the top 3 things you can do to
increase the productivity of your food production efforts, while at the
same time decreasing the amount of effort required to grow all of your
own food, and decreasing the total cost of operating your food
production system.
And when I say decrease operating costs, I mean decrease them to almost
ZERO, especially if you are producing your own nutrients...
High Efficiency
Hydroponics
The ultimate solution to eliminate the cost of your hydroponic nutrients: Imagine a hydroponic system that does not require you to buy any nutrients, does not require you to make your own compost, and does not require you to brew your own nutrient tea. Seriously! No cost and no effort as far as providing nutrients to your plants! Plus, at the end of the gardening cycle you harvest all of your garden vegetables, PLUS YOU HARVEST FISH from the system--->
Aquaponics
This solution is aquaponics. If you are serious about producing all of your own food and being self-sufficient, this is the ultimate solution for reducing expenses (as much as possible), reducing the total amount of work required, and maximizing the productivity of your gardening efforts. I have been gardening for over 24 years, and it is the perfect food production solution in my opinion.
Besides mastering how to make high quality compost, learning aquaponics is one of the top 3 things you can do to increase your garden productivity, reduce your total costs, and reduce your total work. The product that I learned from is called Aquaponics4you. With all of my hydroponic gardening experience, the first time I came across the Aquaponics4you product I knew immediately that it was something very special! Place an aquaponics system outdoors and use the sun instead of grow lights, and you have reduced every garden expense to nearly ZERO!
The Same System/ 10 Weeks Later!
