LED Grow Lights

As winter time fast approaches, the summer window sill season is coming to an end for many of the plants that require more light. This year however, I might be trying a new artificial lighting system, namely LED grow lights. Traditionally, Metal Halides (MH) and High Pressure Sodium (HPS) lights have been used as they have a high output of particular light frequencies which plants need.

As mentioned in previous posts, fluorescent lights typically do not have enough of an intense output to provide the necessary requirement for high energy plants like tomatoes. This means that if you are serious about growing, you will need to invest in a lighting system that will create the necessary lighting requirements for the species of plants.

But there are some drawbacks to these high output lighting systems. The efficiency of the lights themselves are relatively poor, which means a few issues coming to light. One is that the energy not being used for light is primarily turning to heat requiring some form of temperature control in the room to prevent scorching. This is exceptionally true for new growth plants. The other concern is the expense of having these lights operating. If you have a good size garden, say 50 sqft, you are looking at requiring a wattage of about 25W/sqft with 3 - 400 W MH lamps. If you are running this an average of 14 hours per day (16 hours during vegetation and 12 hours during flowering) this adds up to 16.4 kWh per day. Using the US national average for April 2009, this is roughly $60 USD per month. The fact of the matter, is that it adds up pretty fast.

Over the course of a year, that is nearly $750. Starts to make you wonder whether your tomatoes are really worth that much to you!

Why I am thinking of switching to LED Grow Lights

The first reason to go with LED grow lights is the control of the light spectrum used. Plants primarily use blue and red light for synthesis (hence the reflected green color). LED grow lights have the benefit of controlling this spectrum very well.

LED grow lights are exceptionally economical due to the efficiency of transferring energy to light energy instead of heat. LED's require approximately 75% less energy compared to MH or HPS lights. This would be an annual saving of approximately $500 per year.

LED grow lights also last significantly longer than MH or HPS grow lights. A Metal Halide light bulb typically has a rated life of approximately 15,000 hours and the High Pressure Sodium has about 25,000 hours. LED's on the other hand are twice as long as the HPS lights at about 50,000 hours of useable life.

Since the heat is exceptionally lower for the output, there is also less of a need for controlling the temperature of the room. This can also be additional savings with respect to air conditioning cost as well.

The growing results in studies speak for themselves. See this article on NASA and it's development for space farming with LED grow lights.

So, all things considered, I am thinking I might make the switch. I'll keep you posted.

Keep growing!

Indoor Garden Climate, Light, Nutrients, Watering and Pests

Last post I talked about vegetable selection, soil and containers/pots to use. I will continue by talking about Climate, Light, Nutrients, Watering, and Pests!

Indoor Garden Climate and Light Suggestions:

As mentioned, additional light will be a necessary accessory to your indoor garden. There are many different ways in which this can be done depending on the quality of the vegetables you plan on producing.

For the larger leaved vegetables such as spinach, lettuce, cabbage, beets etc. are capable of doing quite well under fluorescent lights with full spectrum or aquarium lighting. Standard fluorescent lights do not have sufficient amounts of the red and blue spectrum and will likely produce meager results. These full spectrum/aquarium lights are readily available in home and garden stores and won't cost you much extra. Cheap 4' light ballasts are also available and can be picked up for relatively cheap. The higher the wattage of bulbs, the better you can expect the plants to do. It is best to have the fluorescent lights adjustable in height as you will want to keep the lights 15cm (6") from the top of the plants. This can be done by using a light hung by a chain which can then be moved up to the next rung when the plant grows.

Having the lights on a timer will work well, set to ensure that a total of 8 hours of light is met. If by a south facing window, have the lights come on at 5 pm or so until 9 pm to give them the extra boost of light required. The plants can also be grown in a basement, however, the timer should ensure 10 hours per day as the light quality is not as good as sunlight. For the broader leafed vegetables, moderate success can be achieved with solely the fluorescent lights.

For tomatoes, peppers, beans etc. which require more light, you may want to think about using a more powerful light to ensure that it does better. I will discuss more advanced lighting techniques in another post however, in bright rooms I have seen tomatoes do relatively well with fluorescent light supplement. However, it is nearly impossible to have a successful yield if using fluorescent lights as the sole light source for these light intense plants.

The broader leafed plants will do better under cooler growing conditions (15'C or ~ 60'F) while the tomatoes and peppers will do better under the warmer (20'C or ~ 70'F) temperatures. In all cases, a bit of air circulation can go a long ways to ensuring the plants are breathing sufficiently, especially during the daily photosynthesis periods. In the evenings, transpiration will produce marginal amounts of carbon dioxide, but in small amounts that will not need additional air circulation. Regardless, air circulation is optional unless you have a dense crop being grown.

Nutrients, Water, and Pests

Fertilizer will be necessary on a regular basis (weekly) as the growing plants will be eating like a teenager. I prefer a natural fertilizer such as seaweed based or fish emulsion, however other options are available from your local home and garden shop. Whatever you do use, be sure that you do not add to much as you can cause some serious problems to your roots and destroy your plants. Fertilizer is not like steriods, you cannot force the plant beyond it's potential just ensure it is getting a balanced diet.

Water levels are important to keep a close eye on. Unlike the indoor herb garden I talked about in my other blog, vegetables are a bit more selective about their environment. Ensure that the plants do not become too dry by watering them regularly. Like you, the plants will not survive without water for long.

On the other hand, do not over water them! Over watering is more common of a problem and will have as much or more effect on the plants. If you see any mold, think about your watering schedule. All the plants may require a bit more or less water than the others so keep an eye on them. If your plants are looking droopy, it is likely in need of a drink. If they are dropping leaves or are not seeing much growth, watch out for over watering. I might get around to discussing hydroponics in a later post.

Growing indoors eliminates many of the pest problems that you typically get outside. However, if you do see any pests such as aphids or meal worms, there are organic soaps which can be used to get rid of them. Do this as soon as you notice them to avoid any spreading to other plants. If used too close to harvest time, ensure to give all your vegetables a good scrubbing before you eat.

All in all, it is a great project and a lot of fun to maintain. Fresh vegetables all year long is a great joy and helps getting through the winters. It's also a great project to have if you have kids and will teach them a lot about how plants grow!

Have fun!