“Now that the northern hemisphere is transitioning into winter, and I have more succulents than ever, what’s the best indoor grow light for me to invest in? Broad-spectrum? Red/blue lights? I’m confused.” Question from Stacy or Portland, Oregon
Answer: Plants always grow best with sunlight, which is full-spectrum. So, if you have a South-facing window that can accommodate your succulents, start there. Then supplement with full-spectrum grow lights where your sun-loving succulents are getting the least light. (Full-spectrum light covers all light wavelengths, from infrared to near-ultraviolet, which plants need to gather energy. This is because plant chlorophyll gathers light at all visible wavelengths and beyond (view the chlorophyll wavelength chart by clicking here).
If you are just illuminating your plants with lighting, then you’ll need strong, full-spectrum lights. Consider the spectrum, lumens (the light amount emitted per second), and lifespan of bulbs before purchasing them. The higher the spectrum, lumens, and lifespan, the better.
Here are your indoor grow light options listed from the lowest to the highest price.
1. Fluorescent Lights: There are several ways to go with fluorescent bulbs. The cheapest way is to use a balance of warm/red and cool/blue bulbs. Together they cover much of the light spectrum, but not all. Some fluorescent bulbs are specially designed for plant growing and cover more of the spectrum–up to 94%. In general, fluorescent bulbs are not very strong, so they must be placed just inches above plants for best light reception and growth. Most growers choose shop-light fixtures, which support long bulbs.
2. Metal Halide (MH) and High-Pressure Sodium (HPS) Lights – These bulbs can be quite expensive (both the bulbs and fixtures) and have high heat output, but they are stronger and can be used to grow larger plants. MH bulbs cover much of the warm/red light spectrum, which is best for foliage growth, while HPS bulbs cover more of the cool/blue spectrum, which is best for flowering. For this reason, these bulbs are often paired to cover a full spectrum for plant growth. If you want to use both bulb types, choose a fixture that will accept each.
4. LED – Great strides have been made regarding full-spectrum LED growing lights, and they are now superior to both fluorescent and MH-HPS options. They can be pricy, but they are long-lasting, full-spectrum, lack heat output, and require less energy. They are also stronger and can be used to grow larger plants. Read the Ask a Garden Expert below to learn more!
I hope that this information helps clarify your question and your succulents shine through the winter.
Black Gold Horticulturist