Are Your Plants Too Far Away from Your Grow Light?
Grow lamps or additional lighting sources can be beneficial for sprouting seeds and enhancing the growth of houseplants, especially when the natural light in your residence isn't ample. However, if your grow lamp is situated too far from your vegetation, its effectiveness diminishes. Here's what you should be aware of to position grow lamps at the appropriate distance, taking into consideration the type of light and the plants you're cultivating.
Why Distance Matters
Similar to sound, light intensity weakens as it spreads further from its source. This decrease happens rapidly, adhering to a mathematical concept known as the inverse square law. Although moving the lamp a few feet further away from the plant's leaves may not appear significant, it can result in a dramatic decrease in light strength. For instance, doubling the distance cuts the light intensity by half, while tripling the distance reduces it to just over 10% of its original strength.
In summary, as the distance increases, light intensity drops significantly. Though powerful industrial lights may still provide sufficient illumination when positioned high up, standard home grow lights placed 4 feet from a plant are largely ineffective.
How Much Light Do Plants Need?
Our eyes evolved to perceive light for sight, not to convert solar energy into food. What appears bright to us, like a well-lit room, might not be enough for certain plants to survive, let alone thrive. Moreover, despite the sun appearing harsh to our eyes on a bright day, many plants necessitate the full spectrum of rays for several hours a day to fuel their growth.
Physical Signs of Too Little Light
Since our eyes are not reliable gauges of light conditions for plants, we can observe the plant symptoms themselves to understand their lighting needs. Signs of insufficient light, such as when the grow light is too far away, include leggy, stretched plants, small, pale leaves, dropped leaves, slowed or non-existent growth, and failure of flowering houseplants, like African violets, to bloom.
If your plants display these physical signs, it might be due to the grow light being too far away or the duration of light exposure being inadequate. Try moving the grow light closer to the plant or relocating the plant closer to the light. If improvements in growth are not observed in a week or two, consider increasing the light exposure as well.
Measuring Light with a Meter
For quantifiable results, you can use a light meter specifically designed for plants. These meters measure only the light frequency beneficial for photosynthesis, which is known as photosynthetically active radiation (PAR). Light meters for plants provide measurements in micromols, not candlepower, foot candles, or lumens.
By placing the light meter next to the plant leaves, you can ascertain the exact amount of light reaching the plant at any given moment. For a plant situated on a windowsill, light intensity may vary throughout the day. Under a grow light, however, it should remain constant.
Light Distance Guidelines
Most homes have only one of three types of lighting: incandescent, fluorescent, or LED. We'll focus on fluorescent and LED lightings, as incandescent bulbs are not ideal for plant lighting due to their high heat production and limited light output.
Fluorescent Lights
Fluorescent lighting can serve as grow lighting, but it has limitations. Due to their low intensity, fluorescent lights must be positioned very close to the plants to maximize their power, as we cannot afford to lose too much intensity to the inverse square law.
For seed-starting and growing young vegetable and flower plants, fluorescent lights need to be 2-4 inches above the plant leaves. The light should be directly above the leaves without touching them (the bulbs can get too warm).
Houseplants require a bit more space, as many popular houseplants thrive in dappled or weaker light. However, keeping the lights within two feet of the plants is often sufficient. As plants grow taller, adjust the fluorescent light fixture to maintain the appropriate height above the plants.
LED Lights
LED lighting is more powerful ceaselessly, even though it uses less electricity. The price of LED lighting has decreased, and as a bonus, you won't have to deal with the hassle of disposing of the spent lighting tubes, like you do with fluorescents when they burn out.
For starting young plants, 8-12 inches above the leaves is a good distance. Houseplants can sometimes be 2-4 feet away, allowing you to group several plants under one light source. Of course, higher-powered LED fixtures can be positioned farther away than low-powered lights. Industrial-strength LED lights are available for purchase, although they are more expensive.
Setting up lights on a timer is the final step to ensuring your plants get the optimal lighting. A timer will automatically switch off the lights at night and turn them back on in the morning, even if you're away from home or had a lazy day off.
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Given the context, here are two sentences that contain the words ['Houseplants', 'Caring for Houseplants', 'BHG', 'Gardening']:
- When caring for houseplants, it's important to consider the appropriate distance between the grow lamp and the plants, as described in a BHG (Better Homes and Gardens) article to ensure the plants receive enough light for growth.
- Gardening enthusiasts can find valuable tips on the distance requirements for grow lamps and the specific light needs of various houseplants in BHG's gardening section, which provides guidance tailored to both beginners and experienced houseplant caretakers.
