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Garden Q&A: Let there be light — for your houseplants

Q: I’d like to learn more about how to use grow lights for my houseplants. I think insufficient light is why some of my plants aren’t thriving. I don’t have good window light and I want to be able to grow more than just species tolerant of low light.

A: I prefer a diverse houseplant collection too, which is why I dove into the artificial light world years ago and haven’t looked back. Today, I grow a variety of plants completely under lights, ranging from orchids, succulents, and tillandsia, to all sorts of foliage plants that fall into the notoriously-vague “bright, indirect light” category.

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You bring up an important point — some houseplants tolerate low light, but none thrive with it. Plants need to be fairly close to a window to make use of its ambient light; displayed too far from even a well-lit window, they may not collect enough energy for long-term health. At the very least, growth will be glacial in pace and blooming very sporadic or lacking entirely.

Plant lights (grow lights) are necessary to support plant growth and flowering when natural light isn’t bright enough. They can either supplement natural light or they can be the only light plants receive. What’s important is the quality and quantity of this light “diet” (photosynthesis is a plant’s way of feeding itself, after all), so what fixture you choose and how you use it go a long way toward success and cost-effectiveness.

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Two commonly used light types are fluorescents and LEDs. They can be screw-in styles for a typical lamp socket or they can be housed in their own plug-in fixture. They’re going to need to be fairly close to foliage — often a foot or two away, depending on intensity — which is why ceiling and other ambient home lighting isn’t enough for plants to survive on.

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Costs and fixture quality can vary wildly, so do some research before buying. There are several technical terms used in measuring and reporting light performance values, and while understanding them isn’t critical to choosing a light that will work, using them to compare products helps you make the best selection to suit your needs and budget. You can learn about these terms, plus how plants react to light, in my multipart series on the Maryland Grows blog.

In general, opt for a white light that is easy for you to hang or mount near your plant. Full-spectrum lights not only look neutrally white to our eyes — useful in monitoring for ailments as well as enjoying a plant’s true colors — but they also provide a range of light hues balanced to mimic sunlight. Those wonky fuchsia-colored LEDs with the combo of red and blue lights may have their place in indoor farms, but while those hues are indeed key in photosynthesis, they aren’t the only light colors plants utilize. Besides, that’s a harsh color to have in your living space.

Web research on lighting choices will lead to hobby forums (aquariums, vivaria, hydroponics, orchids, etc.) and multiple discussions about which fixtures and color blends are recommended. Keep in mind that the nuances of performance aren’t a deal-breaking factor, and plenty of people have success with simple, inexpensive bulbs and fixtures found at a hardware store — a fact you’ll quickly pick up on if you read through enough debates on which lights are best. Your plant light setup can be as simple or as fancy as you’d like. The important aspect is to observe your plants as they adapt to new conditions and adjust your care accordingly. Over time, assuming their other needs are being met, you should see improvements in appearance and growth.

Q: I enjoy roses but want to grow native plants when possible. Do we have native roses? I know the white multiflora rose I see everywhere is invasive.

A: We do, though they’re not nearly as common in commerce; native nurseries may stock them. The three main Maryland species are carolina or pasture rose (rosa carolina), swamp rose (rosa palustris), and Virginia rose (rosa virginiana).

All occur statewide, or at least in each of our main regions — mountain, piedmont, and coastal plain. You don’t get much choice in flower color (pink) or form (single), and fragrances might be weaker than some hybrid roses, but they’ll be of better value to wildlife if not sprayed or deadheaded. As with many roses, they’ll look best when mixed with other perennials or shrubs so the planting as a whole has multi-season interest.

University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Extension” to send questions and photos.


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