Noob, Grow Light question

by Steve
(Cincinnati, Ohio)

If I were to start with a 4' x 4' foot garden what type of garden grow light should I use? Will just one of the more expensive higher-power grow lights be sufficient? How deep should the grow boxes be to accomodate root growth? Thanks for any help you can give, and have a great week.

Answer: To Steve and all noobs-

A 4'x 4' indoor garden is the ideal size for a 600 watt high pressure Sodium light or a 600 watt Metal Halide light. Both produce excellent results, as long as all of the other needs of your plants are met over the course of the growing period. Some plants require less than "full sun" to produce fruits, flowers, and fresh herbs (lettuce, spinach, and basil for a few examples). If you are growing a garden that will do well with less-than-full sun, then you could light your garden with two 2'x 4' fluorescent grow lights (specifically the Tek T5 lights).

Keep in mind the stronger the grow light, the stronger the exhaust fan you will need for the garden. A 600 watt light will require approximately a 400 CFM fan (or more) to cool it. A huge goal for the indoor garden space should be a running temperature of 72 degrees. The main thing you can do to accomplish this is to cool your light separately from the grow room. This strategy requires two exhaust fans, but is worth it....

To cool the grow light, pull air from somewhere outside the grow room (ideally with 6 inch duct minimum) through your grow light (which should be fully enclosed with glass in the bottom, and have 6" vent holes for the 6" ducting) and exhaust the air outside of the grow room with the first exhaust fan. To cool the grow room itself, you should be running an air conditioner in the grow room, or else pumping air-conditioned air from a third location (an adjacent room?) into the grow room with yet another fan. An exhaust fan should be put on a thermostat to kick on whenever the temperature gets too high (82 degrees, for example), and the exhaust run should be started as high in the grow room as possible (to exhaust the hottest air first).

If you are considering building a soil box beneath your grow lights, it should be about 4'x 4', and can be anywhere from about 6 inches deep, to about 18 inches deep, depending on exactly how big the finished plants are going to be. Bigger plants will require bigger root systems, and obviously more nutrients to grow both big and healthy. Tomatoes are a relatively heavy feeding garden plant (as are most vegetable producers), and also commonly finish their life cycle at about 3' or 4' tall. For this type of garden, I would use about 16 inches of soil. However, if you keep them well pruned so they finish shorter, I would say to make a 12 inch deep soil box.

You may have your heart set on organic gardening in soil, but no matter how nutritious you make your initial garden soil mix you will very probably need to apply additional nutrients at some point in the growing cycle. Here is my point- the soil in the soil box can be made less-deep, as long as you recognize that the plants will run out of the nutrients in the soil more quickly. Really the soil box only needs to be deep enough to provide support to your plants, as long as you are prepared to give them the nutrients they need (in their water) once they begin to use up all of the nutrients in the soil mix that you begin with.

I hope this helps everyone out there!

And Happy Growing!

Click here to post comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Ask the Hydroponic Gardening Expert.

All of the items that I personally use and recommend!

AffordableGarden Design&Setup

(10 week update below)

Find out the cheapest and easiest ways to garden productively in this article.

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 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

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--->


Click Here to learn more!

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.

Produce garnden vegetables AND fish together. Eliminate fertilizer costs!

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!

If you've found this site helpful at all, I would really appreciate it