How grow lights can help your houseplants and seedlings - East Idaho News
IN THE GARDEN

How grow lights can help your houseplants and seedlings

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Plants need light to grow, and while natural sunlight is ideal, artificial lighting can also support healthy growth, especially for indoor plants and seedlings. Artificial lights provide an optimal environment, allowing plants to thrive before being transplanted outdoors.

When choosing grow lights, it’s important to check the product’s Correlated Color Temperature (CCT) and Color Rendering Index (CRI). CCT, measured in Kelvins (K), indicates the light’s color, with a rating of around 6500K being ideal for plant growth, as it closely resembles natural daylight. CRI measures how accurately the light mimics natural sunlight, with a maximum rating of 100. For indoor gardening, a CRI above 85 is recommended for better light quality.

Light quality refers to the wavelength or color of light, with plants using primarily red and blue light for photosynthesis (Photosynthetically Active Radiation, or PAR). Modern grow lights often emit red and blue light. Many LED lights allow you to adjust the light quality, enabling you to tailor the colors of light for specific plant needs, such as promoting growth or encouraging blooming. When buying, check the label for light type: blue or mixed lights are best for seedlings, leafy greens, and non-flowering plants, red or mixed lights promote bud formation in flowering plants and help keep them shorter, and white or balanced lights suit most plants at any growth stage.

The four main types of grow lights are LED, fluorescent, high-intensity discharge (HID) lamps, and incandescent lamps. LEDs are energy-efficient, long-lasting (up to 50,000 hours), and emit low heat, but they come with a higher initial cost and can have limited coverage. Fluorescent lamps are affordable and efficient, though they have shorter lifespans (around 10,000 hours) and are less efficient than LEDs. HID lamps offer high light output and a broad spectrum but consume a lot of energy, produce heat, and have a lifespan of about 24,000 hours. Incandescent lamps are rarely used due to their inefficiency and short lifespan (750-1,000 hours).

The placement of grow lights is crucial to the success of your plants. If the lights are placed too far away, plants may become “leggy,” stretching toward the light source and growing tall with weak stems. Conversely, placing the lights too close can result in heat stress and leaf scorching, damaging the plants. A general guideline is to position the lights 6–12 inches above the plants, adjusting as they grow. Regularly check for signs of stress, such as yellowing leaves or stunted growth, which can indicate improper light placement.

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Grow lights should be placed 6 to 12 inches above the plants and should be adjusted as the plants grow. | Adobe Stock

To use grow lights effectively, choose the right light type based on your plants’ needs for light intensity, spectrum, and duration. Most plants require 12 to 16 hours of light daily, followed by a period of darkness. Seedlings need 16-18 hours of light, while hydroponic lettuce and herbs thrive with 12-14 hours. Foliage houseplants require 12-14 hours, and flowering houseplants benefit from 14-16 hours of light. Timers can automate this cycle for consistency. Since grow lights, especially HID lamps, produce significant heat, ensure proper ventilation to maintain a stable temperature and prevent overheating.

Houseplants require the right amount of light based on their specific needs, which range from low to high light. Low-light plants, like Chinese evergreen and peace lily, thrive in shaded areas with indirect light, such as north-facing windows. Medium-light plants, including rubber plant and spider plant, do well in areas with moderate, indirect light, like east-facing windows or office spaces. High-light plants like succulents, hibiscus, and culinary herbs need direct sunlight from south- or southwest-facing windows. For medium- and high-light plants, grow lights are an effective solution to ensure they get the necessary light for healthy growth, especially in spaces with limited natural sunlight.

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