Top 10 Questions About Lighting

By Teo Spengler | July 28, 2019
Image by RomoloTavani
by Teo Spengler
July 28, 2019

Here at Gardening Know How we get lots of questions, and our goal is to provide answers to those inquiries to the best of our knowledge. Of these includes lighting for plants in the home and garden. The following information includes the 10 most commonly asked questions relating to garden lighting, both indoors and in the landscape.

1. How much sunlight is considered “part sun”?

You’ll have the greatest success with your planting if you site each shrub or tree in a location where it gets appropriate light. But look out. “Appropriate” means illumination that works for the particular plant. Some like direct sun, as much as possible. Others prefer shade. Then there is the middle ground where your new garden invitee does best in “part sun.” There is no hard and fast rule for exactly how much sun this means, but generally, it means quarter-day to half-day, or three to six hours a day of sun.

2. Does sun through a cloud still count as direct sunlight?

While some plants require direct sunshine covering their leaves to bloom or fruit, others hate it. It pays to cater to your plant’s requirements in this regard since letting these plants get direct sun exposure can kill them. Although clouds seem to “block” sun, they actually don’t block all sun rays, so letting a plant sit in a direct sun area under cloud cover is risky. Also, remember, there is nothing more mobile than a cloud, and if it slips away for even a few moments, you get the heat of the sun as well. If you have indoor plants that fit into the no-direct-sun category, keep them away from a window that gets direct afternoon sun, even when there are clouds. Or select a different window that only gets light morning sun.

3. Is there any difference between LED lights and LED grow lights?

LEDs are “light emitting diodes” that offer efficient electric lighting and have a lifespan up to 25 times longer than incandescent lamps.

A grow light is an artificial light source designed to stimulate plant growth, usually used where there is inadequate natural light for a plant. It puts out a light appropriate for photosynthesis to provide a range of light spectrums (both cool and warm) similar to that of the sun. You can get grow lights in different colors, temperatures and intensities to match different types of plants, stages of cultivation and plant needs.

LED grow lights are LED lights that you can buy in different colors (wave lengths) and intensity. For some plants, the ideal color and intensity may be the same as you use for lighting purposes. However, regular LED lights are often in either warm spectrum or cool spectrum so plants don’t get the full range they require.

4. What happens if a plant has too much light?

Not every person reacts the same when they get too much sun. Some people have light skin that flares into red, others get tans, and still others burn and peel. Plants are the same and their reactions to “too much sun” varies just like us. They can even suffer from sunburn damage when exposed to intense sunlight. Generally, you may see anything from curling or wilting leaves to signs of scorching to plant death.Give a plant the sunlight exposure it needs to avoid problems.

5. Do plants need light to grow?

All plants need some kind of light. But the amount required is different from plant to plant. Some plants require a lot of light, others just a little. In the wild, understory plants are those that need less sun. Unless, a plant is specifically designed to grow under low light conditions, it’s best to provide them with at least some sunlight. Too little light prevents photosynthesis from occurring, which is how plants acquire their energy to survive.

6. How does light affect plant growth?

Sunlight sustains all living things on the earth, including plants. While humans get energy from the food they eat, plants produce their energy themselves through a process called photosynthesis.They collect the light from their leaves and transform it into the energy they require to grow, bloom and reproduce. Although each plant has different sunlight requirements, thus affecting them differently, a plant deprived of sunlight will usually die.

7. Do streetlights affect plant growth in a vegetable garden?

In normal circumstances, streetlights don’t impact the growth of veggies in your garden, or any other plants for that matter. If you were to switch out the lamp to use a grow light bulb, which is not something you should try, you might see some effect, but streetlights are usually quite a bit higher than your average garden. Additionally, the light given off by street and landscape lighting, in most cases, is not intense enough to affect plant growth. That said, for some plants, like trees, you may notice more or continued growth on the parts receiving this constant light. Other plants, which may require periods of complete darkness prior to blooming could show signs of delayed flowering.

8. Does using lighting to grow plants indoors affect the overall health of the plants?

Usually, the reason a gardener brings in grow lights is to help the plant grow. So, to the extent that indoor lighting fulfills a plant’s sunlight requirements, it does help. However, if you are talking about regular indoor lighting, the impact is usually much less. Plants require both a warm and cool light spectrum for ideal growth. In the house, typically lights are either warm spectrum or cool spectrum, so plants don’t get the full range they require. Grow lights, however, often have both spectrums.

9. How many hours of sunshine does a vegetable need?

While different vegetables have different sun requirements, all need light. On average, veggies need between six and eight hours a day of sunlight to grow and thrive. There are, however, a handful of vegetable plants that will tolerate shade conditions.

10. How/when to plant “leggy” seedlings?

You are likely to get leggy seedlings if the young plants don’t get enough light. Plant them promptly into a spot with more light and they should resume normal growth. The same is true of basically any plant that becomes “leggy.” This happens as the plants stretch out to find better lighting.

We all have questions now and then, whether long-time gardeners or those just starting out. So if you have a gardening question, get a gardening answer. We’re always here to help.

This article was last updated on
Read more about Top 10 Plant Q&A
Did you find this helpful? Share it with your friends!

Browse Dozens of Our FREE Gardening Guides Today

Whether your dream garden is a houseplant sanctuary, a bountiful vegetable garden, a pollinator paradise, a bright and bold flower bed, or a backyard oasis – Gardening Know How has the perfect gardening guide just for you.

Click the button below to access more than 3 dozen of our completely free and completely comprehensive guides to growing your dream garden.

Join Us - Sign up to get all the latest gardening tips!