Whether you are trying to keep your houseplants healthy year round, start some seedlings early or have a nice kitchen herb garden, giving your plants the light they need is critical. Plants benefit from all wavelengths of light but the reds and blues are the most important. This can make it tricky to accomplish the ideal light conditions for you plants.
Types of bulbs
Incandescent bulbs supply a good amount of red light (2700K) but virtually no blue (6500K) so they don’t have the proper wavelength to keep your plants healthy. They also run quite hot and have a much shorter lifespan than other options. They are not recommended.
CFLs or Compact Fluorescent and linear fluorescent lights are a good option on the cheaper side and your local hardware store, grow store, and online will have a variety of spectrum choices. They use 1/3-1/5 the energy of incandescent, last 8-15 times longer, and are 3-4 times brighter. A bulb labeled as warm white will be 2700K, neutral white 3000-5000K, cool white 4100-4500K, and daylight 5000-6500K.
LEDs can have a higher initial investment but use the least energy, have the longest lifespan, and the widest variety of spectrum options including ones specifically designed for horticulture. These are what we recommend if you have the budget. There are many bulbs on the market now that are specific for photosynthesis and may use the Kelvin ratings or PAR measurement so you can get the right spectrum at the right growing stage.
HPS or high pressure sodium has been the standard in horticulture lighting during the flowering/fruiting cycle for quite a while. They run very hot and will need fans to cool both the fixture and the room. They also lack sufficient blue light for use without natural light or another light source. They are quickly being replaced by LED’s because of LED’s low heat output and energy efficiency.
MH or metal halide is the counterpart for the high pressure sodium. Metal halide lights will have plenty of blue light and are generally used to promote vegetation. A good plan would be to begin with these for full, healthy foliage and switch to HPS for the flowering period.
Florescent fixtures for tubes are easy to find and inexpensive. Your local hardware stores usually carry a 2’ linear fixture for $20 or less. Your local grow store will have a great selection. You can find a huge variety online to order. For a nice inexpensive system, I use. For a great quality, also recommended.
Standard incandescent fixtures will accept many compact florescent and LED bulbs. These can be used directly over a plant for spot coverage. Special air-cooled bulb reflectors or enclosures will be needed for HPS and can be found where other horticulture/hydroponic supplies are sold. For example: you can begin with MH for vegetative growth then switch to HPS for the flowering cycle.
Specially designed LED fixtures and HPS/metal halide fixtures are quite a bit more expensive but will give you the most options and best area coverage.
If you are on a budget you can get away with a few standing lamps with multiple independently adjustable fixtures. With this plan you will need a few different bulbs, some warm light and some cool white, somewhere between an even split and a ratio of 3cool/2warm.