Dual-band LEDs that mix primarily red and blue light produce light that looks pink to purple in color. You can use this mixture for continuous growth through vegetative and flowering stages.

You can also use single-band nanometer-specific blue LEDs for vegetative growth, then add red if your plants need to flower. Or bulk up young vegetative plants using single-band red LEDs, then add in blue light to encourage flowering.

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LEDs lamps are available in other configurations: large multiband fixtures for inside grow tents and grow rooms, light bars you can mount or hang from shelves or cabinets, and even flexible strips you can wind around fixtures you build or the inside of grow tents or closets.

You can also use LED strips to build your own LED hanging fixtures. These options give you the ability to interlight plants, or to run lighting between plants to improve growth on the lower areas.

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There are also dual-watt and dual-lamp fixtures that allow you to use lamps of varying wattages and switch between MH and HPS lamps in the same fixture.

This is handy if you are transitioning young seedlings, cuttings, or plants in their vegetative phase to mature fruiting plants that consume more energy.

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The difference in the efficacy of the varied color spectrums of light on actual photosynthesis is called the quantum efficiency curve, or yield photon flux (YPF) curve.

If you take measurements using a standard quantum flux meter under a lamp that generates only blue light, you are going to get good PPF and PPFD values, even though blue light is less efficient at stimulating photosynthesis than red light.

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Not all lighting manufacturers understand how to properly measure and present light outputs for plant growth. As the label below shows, the lamp manufacturer included measurements of lux, but no PPF information. In fact, the label mixes up PAR and lux measurements in an attempt to provide PPFD measurements at different distances from the plant. But, as you now know, lux and PAR are distinct measurements.

Unfortunately, far too many lamps include this kind of incorrect information.

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Lettuce is a great candidate for direct seeding. These seeds can be sown directly in the the final pot, without the extra step of transplanting. Be sure to read the seed packet for planting instructions.

After the seedlings germinate, be sure to thin them so they aren't overcrowded in the pot. You can then continue to grow your lettuce in the same container until harvest.

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The light produced from metal halide (MH) lamps looks white and bright with a cool visual temperature. While you can also use MH lamps during the flowering stages of growth, many growers employ them only when growing seedlings, cuttings, or vegetative transplants, or bulking up vegetative growth on larger plants.

MH Lamps generally emit a light spectrum range that closely mimics that of natural sunlight, weighted to the blue and violet spectrum, so they are good for all vegetative stages of plant growth.

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Multicolor white LEDs, also known as RGB LEDs, mix separate red, blue, and green diodes together in a balance to create white-colored light that is both visually pleasing and efficient for plant growth.

RGB LEDs are a bit more complicated to manufacture than standard white full-spectrum LEDs, so they may cost more.

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