Grow Lights for Indoor Plants and Indoor Gardening: An Overview
By Brian Barth
Indoor growing offers many advantages. The biggest benefits are the most obvious: garden pests can't get at your plants, and you have total control over the weather.
Yet unless you're lucky enough to have a solarium or greenhouse attached to your home, providing sufficient light to your plants will likely be an obstacle (shade-tolerant houseplants excepted). South-facing windows may provide enough light for a tray or two of seedlings, but if you want to grow vegetables, or any other sun-loving plants, to maturity, you're going to need grow lights.
The indoor lighting found in most homes does little to support photosynthesis. Traditional incandescent bulbs do not have the proper spectrum of light, or intensity, to supplant the sun. Household fluorescent bulbs can make effective grow lights, but only if they are placed in within a few inches of the foliage and left on for 16 hours per day—not ideal.
Warm vs Cool: Understanding Color Spectrum in Grow Lights
When shopping for grow lights, you'll notice they are labeled with numbers like 2700K or 4000K. This refers to their relative warmth or coolness on the color spectrum—the higher the number, the cooler the light. Foliage growth is generally best around 6500K, though many plants need a period of warmer light, around 3000K, in order to produce flowers, and thus fruit.
In other words, if your goal is to simply produce seedlings, leafy green vegetables, or root crops, you only need higher spectrum bulbs. If you want to grow flowers, marijuana, or any fruiting plant (cucumbers, tomatoes, peppers, lemons, etc.), you'll also require low spectrum bulbs. You can find some types of bulbs available in full-spectrum form, however, simplifying things.
Types of Grow Lights
There are three main types of grow lights.
Full-spectrum fluorescent lights—either of the tube or standard CFL variety—are a great choice when starting seeds indoors. Falcona / Shutterstock.com
Fluorescent Grow Lights
The standard fluorescent bulb, commonly denoted T12, makes a decent grow light for houseplants, starting seeds, supplementing the natural light of a window, and other situations where lighting needs are modest. They are fairly weak in light intensity, however, and must be placed within a few inches of the foliage to have much of an effect.
T5 fluorescent bulbs, which are narrower in diameter than T12s (but still widely available wherever lightbulbs are sold), have a much higher light intensity, making them suitable as a sole light source for sun-loving plants. Compact fluorescent bulbs (CFLs) are an option for small spaces, or if you don't like the look of long rectangular fluorescent light fixtures—CFLs will screw into an ordinary incandescent light fixture.
LED Grow Lights
While they are considerably more expensive than fluorescent bulbs, LEDs use half the electricity and last five times longer, more than paying for themselves in the long run. The average LED bulb from the hardware store is not designed for plant growth, however—you need special LED grow bulbs, a relatively new technology that is increasingly available from horticultural suppliers.
LED grow bulbs are capable of much greater light intensity than fluorescent bulbs and are available in full-spectrum form. An easy rule of thumb: Fluorescent bulbs are often used when growing just a handful of plants; LEDs are preferable for larger quantities since you can achieve higher light intensity per square foot. Another advantage of LEDs? They produce very little heat compared to other bulbs—an issue that can become problematic when you have a lot of lights in a small space.
HID Grow Lights
Before the advent of LED grow lights, HID (high-intensity discharge) lights were the main option for large indoor plantings. They are extremely powerful, but are expensive to purchase, consume electricity inefficiently, require special light fixtures, and give off a lot of heat. All that said, they are very effective and are still widely used. If you want to grow large plants like tomatoes or lemon bushes, HIDs are a good bet because the light penetrates farther into the foliage than with other bulbs.
There are two types of HID bulbs. High-pressure sodium (HPS) bulbs are best for flowering (low spectrum), while MH (metal halide) bulbs are required to support vegetative growth (high spectrum); the two types are often used in conjunction. Unfortunately, each type requires its own fixture.
How to Install Grow Lights
Installation requirements vary drastically depending on the scope of your indoor garden and the type of bulb used. But here are a few basic steps to get you started.
Figure out how many bulbs you need.
Most edible plants require at least 30 watts per square foot, but fruiting species (like tomatoes) generally won't produce abundant high-quality crops without 40 to 50 watts per square foot. Wattage is always indicated on the bulb package. Simply multiply the square footage of your growing area by the number of watts you plan to provide (between 30 and 50); then divide by the number of watts supplied by the bulbs you plan to use.
Devise a light rack.
You'll need a way to support the bulbs over the plants at the proper height. And unless you're growing something that will remain at more or less the same height throughout its lifespan, you'll also need a way to raise the light rack as the plants grow. This is usually accomplished through some sort of pulley system or by hanging the light fixtures with metal chain—that way you can easily adjust the height by changing the link the light fixture is home from. Grow light racks are also available for purchase online.
Add the necessary accoutrements.
It is generally wise to plug your lights into a timer to ensure they get the proper amount of light, and that they get it at the same time each day. Fancy ones are available for indoor growing, though a standard lamp timer also works. If your lights bring the temperature above 80 degrees or so in your growing area, install a ventilation system to prevent heat stress. Aficionados make use of reflectors and all sorts of other grow light accessories to achieve optimum results.
How Long Should I Leave Grow Lights On?
Plants grown indoors require more hours of light than those grown outdoors—14 to 18 hours of light per day is recommended for most edible species when grown under artificial lighting. Don't be tempted to leave the lights on 24/7, however—at least six hours of darkness each day is essential to plant health.
As the plants grow, raise the light fixture accordingly to maintain the optimal distance, which varies depending on the type of bulb used and its wattage (the higher the wattage, the farther away the bulb can be). Here are the basic parameters:
Fluorescent Grow Light: 3 to 12 inches
LED Grow Light :12 to 24 inches
HID Grow Light: 24 to 60 inches
Spring Into Action: 6 Tips for Climate-Smart Gardening https://t.co/vMmP1ZfCi1 @TheCCoalition @beyondzeronews— EcoWatch (@EcoWatch)1520078710.0
Reposted with permission from our media associate Modern Farmer.
By Michael Svoboda, Ph.D.
Despite a journey to this moment even more treacherous than expected, Americans now have a fresh opportunity to act, decisively, on climate change.
The authors of the many new books released in just the past few months (or scheduled to be published soon) seem to have anticipated this pivotal moment.
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EcoWatch Daily Newsletter
By Katy Neusteter
The Biden-Harris transition team identified COVID-19, economic recovery, racial equity and climate change as its top priorities. Rivers are the through-line linking all of them. The fact is, healthy rivers can no longer be separated into the "nice-to-have" column of environmental progress. Rivers and streams provide more than 60 percent of our drinking water — and a clear path toward public health, a strong economy, a more just society and greater resilience to the impacts of the climate crisis.
Public Health<img lazy-loadable="true" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTUyNDY3MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2MDkxMTkwNn0.pyP14Bg1WvcUvF_xUGgYVu8PS7Lu49Huzc3PXGvATi4/img.jpg?width=980" id="8e577" class="rm-shortcode" data-rm-shortcode-id="1efb3445f5c445e47d5937a72343c012" data-rm-shortcode-name="rebelmouse-image" data-width="3000" data-height="2302" />
Wild and Scenic Merced River, California. Bob Wick / BLM<p>Let's begin with COVID-19. More than <a href="https://www.nytimes.com/interactive/2020/us/coronavirus-us-cases.html?name=styln-coronavirus&region=TOP_BANNER&block=storyline_menu_recirc&action=click&pgtype=LegacyCollection&impression_id=2f508610-2a87-11eb-8622-4f6c038cbd1d&variant=1_Show" target="_blank">16 million Americans</a> have contracted the coronavirus and, tragically,<a href="https://www.nytimes.com/interactive/2020/us/coronavirus-us-cases.html?name=styln-coronavirus&region=TOP_BANNER&block=storyline_menu_recirc&action=click&pgtype=LegacyCollection&impression_id=2f508610-2a87-11eb-8622-4f6c038cbd1d&variant=1_Show" target="_blank"> more than</a> <a href="https://www.nytimes.com/interactive/2020/us/coronavirus-us-cases.html?name=styln-coronavirus&region=TOP_BANNER&block=storyline_menu_recirc&action=click&pgtype=LegacyCollection&impression_id=2f508610-2a87-11eb-8622-4f6c038cbd1d&variant=1_Show" target="_blank">300,000 have died</a> due to the pandemic. While health officials encourage hand-washing to contain the pandemic, at least <a href="https://closethewatergap.org/" target="_blank">2 million Americans</a> are currently living without running water, indoor plumbing or wastewater treatment. Meanwhile, <a href="https://www.theguardian.com/us-news/2020/jun/23/millions-of-americans-cant-afford-water-bills-rise" target="_blank">aging water infrastructure is growing increasingly costly for utilities to maintain</a>. That cost is passed along to consumers. The upshot? <a href="https://research.msu.edu/affordable-water-in-us-reaching-a-crisis/" target="_blank">More than 13 million</a> U.S. households regularly face unaffordable water bills — and, thus, the threat of water shutoffs. Without basic access to clean water, families and entire communities are at a higher risk of <a href="https://www.americanprogress.org/issues/green/news/2020/08/05/488705/bridging-water-access-gap-covid-19-relief/" target="_blank">contracting</a> and spreading COVID-19.</p><p>We have a moral duty to ensure that everyone has access to clean water to help prevent the spread of the coronavirus. Last spring, <a href="https://nymag.com/intelligencer/2020/03/coronavirus-stimulus-bill-explained-bailouts-unemployment-benefits.html" target="_blank">Congress appropriated more than $4 trillion</a> to jumpstart the economy and bring millions of unemployed Americans back to work. Additional federal assistance — desperately needed — will present a historic opportunity to improve our crumbling infrastructure, which has been <a href="https://www.theguardian.com/us-news/2020/jun/23/millions-of-americans-cant-afford-water-bills-rise" target="_blank" rel="noopener noreferrer">grossly underfunded for decades</a>.</p><p>A report by my organization, American Rivers, suggests that <a href="https://s3.amazonaws.com/american-rivers-website/wp-content/uploads/2020/07/09223525/ECONOMIC-ENGINES-Report-2020.pdf" target="_blank" rel="noopener noreferrer">Congress must invest at least $50 billion</a> "to address the urgent water infrastructure needs associated with COVID-19," including the rising cost of water. This initial boost would allow for the replacement and maintenance of sewers, stormwater infrastructure and water supply facilities.</p>
Economic Recovery<p>Investing in water infrastructure and healthy rivers also creates jobs. Consider, for example, that <a href="https://tinyurl.com/y9p6sgnk" target="_blank">every $1 million spent on water infrastructure in the United States generates more than 15 jobs</a> throughout the economy, according to a report by the Value of Water Campaign. Similarly, <a href="https://tinyurl.com/yyvd2ksp" target="_blank">every "$1 million invested in forest and watershed restoration contracting will generate between 15.7 and 23.8 jobs,</a> depending on the work type," states a working paper released by the Ecosystem Workforce Program, University of Oregon. Healthy rivers also spur tourism and recreation, which many communities rely on for their livelihoods. According to the findings by the Outdoor Industry Association, which have been shared in our report, "Americans participating in watersports and fishing spend over <a href="https://s3.amazonaws.com/american-rivers-website/wp-content/uploads/2020/06/30222425/Exec-summary-ECONOMIC-ENGINES-Report-June-30-2020.pdf" target="_blank">$174 billion</a> on gear and trip related expenses. And, the outdoor watersports and fishing economy supports over <a href="https://s3.amazonaws.com/american-rivers-website/wp-content/uploads/2020/06/30222425/Exec-summary-ECONOMIC-ENGINES-Report-June-30-2020.pdf" target="_blank">1.5 million jobs nationwide</a>."</p><p>After the 2008 financial crisis, Congress invested in infrastructure to put Americans back to work. The American Recovery and Reinvestment Act <a href="https://thehill.com/blogs/congress-blog/economy-a-budget/25941-clean-water-green-infrastructure-get-major-boost" target="_blank">of 2009 (ARRA) allocated $6 billion</a> for clean water and drinking water infrastructure to decrease unemployment and boost the economy. More specifically, <a href="https://www.conservationnw.org/news-updates/us-reps-push-for-millions-of-restoration-and-resilience-jobs/" target="_blank" rel="noopener noreferrer">an analysis of ARRA</a> "showed conservation investments generated 15 to 33 jobs per million dollars," and more than doubled the rate of return, according to a letter written in May 2020 by 79 members of Congress, seeking greater funding for restoration and resilience jobs.</p><p>Today, when considering how to create work for the <a href="https://www.bls.gov/news.release/pdf/empsit.pdf" target="_blank" rel="noopener noreferrer">10.7 million</a> people who are currently unemployed, Congress should review previous stimulus investments and build on their successes by embracing major investments in water infrastructure and watershed restoration.</p>
Racial Justice<p>American Rivers also recommends that Congress dedicate <a href="https://s3.amazonaws.com/american-rivers-website/wp-content/uploads/2020/07/09223525/ECONOMIC-ENGINES-Report-2020.pdf" target="_blank" rel="noopener noreferrer">$500 billion for rivers and clean water over the next 10 years</a> — not just for the benefit of our environment and economy, but also to begin to address the United States' history of deeply entrenched racial injustice.</p><p>The <a href="https://www.epa.gov/npdes/sanitary-sewer-overflows-ssos" target="_blank" rel="noopener noreferrer">23,000-75,000 sewer overflows</a> that occur each year release up to <a href="https://www.americanrivers.org/2020/05/fighting-for-rivers-means-fighting-for-justice/#:~:text=There%20are%20also%2023%2C000%20to%2075%2C000%20sanitary%20sewer,to%20do%20with%20the%20mission%20of%20American%20Rivers." target="_blank" rel="noopener noreferrer">10 billion gallons of toxic sewage</a> <em>every day</em> into rivers and streams. This disproportionately impacts communities of color, because, for generations, Black, Indigenous, Latinx and other people of color have been <a href="https://www.scientificamerican.com/article/flooding-disproportionately-harms-black-neighborhoods/" target="_blank" rel="noopener noreferrer">relegated</a> to live in flood-prone areas and in neighborhoods that have been intentionally burdened with a lack of development that degrades people's health and quality of life. In some communities of color, incessant flooding due to stormwater surges or <a href="https://www.ajc.com/opinion/opinion-partnering-to-better-manage-our-water/7WQ6SEAQP5E4LGQCEYY5DO334Y/" target="_blank" rel="noopener noreferrer">combined sewer overflows</a> has gone unmitigated for decades.</p><p>We have historically treated people as separate from rivers and water. We can't do that anymore. Every voice — particularly those of people most directly impacted — must have a loudspeaker and be included in decision-making at the highest levels.</p><p>Accordingly, the new administration must diligently invest in projects at the community level that will improve lives in our country's most marginalized communities. We also must go further to ensure that local leaders have a seat at the decision-making table. To this end, the Biden-Harris administration should restore <a href="https://www.epa.gov/cwa-401#:~:text=Section%20401%20Certification%20The%20Clean%20Water%20Act%20%28CWA%29,the%20United%20States.%20Learn%20more%20about%20401%20certification." target="_blank">Section 401 of the Clean Water Act</a>, which was undermined by the <a href="https://earthjustice.org/news/press/2020/tribes-and-environmental-groups-sue-trump-administration-to-preserve-clean-water-protections#:~:text=Under%20Section%20401%20of%20the%20Clean%20Water%20Act%2C,seeks%20to%20undermine%20that%20authority%20in%20several%20ways%3A" target="_blank">Trump administration's 2020 regulatory changes</a>. This provision gives states and tribes the authority to decide whether major development projects, such as hydropower and oil and gas projects, move forward.</p>
Climate Resilience<p>Of course, the menacing shadow looming over it all? Climate change. <a href="https://media.ifrc.org/ifrc/wp-content/uploads/2020/11/IFRC_wdr2020/IFRC_WDR_ExecutiveSummary_EN_Web.pdf" target="_blank">More than 100 climate-related catastrophes</a> have pummeled the Earth since the pandemic was declared last spring, including the blitzkrieg of megafires, superstorms and heat waves witnessed during the summer of 2020, directly impacting the lives of more than <a href="https://media.ifrc.org/ifrc/wp-content/uploads/2020/11/IFRC_wdr2020/IFRC_WDR_ExecutiveSummary_EN_Web.pdf" target="_blank">50 million people globally</a>.</p><p>Water and climate scientist Brad Udall often says, "<a href="https://www.youtube.com/watch?v=xQhpj5G0dME" target="_blank">Climate change is water change</a>." In other words, the most obvious and dire impacts of climate change are evidenced in profound changes to our rivers and water resources. You've likely seen it where you live: Floods are more damaging and frequent. Droughts are deeper and longer. Uncertainty is destabilizing industry and lives.</p><p>By galvanizing action for healthy rivers and managing our water resources more effectively, we can insure future generations against the consequences of climate change. First, we must safeguard rivers that are still healthy and free-flowing. Second, we must protect land and property against the ravages of flooding. And finally, we must promote policies and practical solutions that take the science of climate disruption into account when planning for increased flooding, water shortage and habitat disruption.</p><p>Imagine all that rivers do for us. Most of our towns and cities have a river running through them or flowing nearby. Rivers provide clean drinking water, irrigate crops that provide our food, power our homes and businesses, provide wildlife habitat, and are the lifeblood of the places where we enjoy and explore nature, and where we play and nourish our spirits. Healthy watersheds help <a href="https://news.un.org/en/story/2020/03/1059952" target="_blank" rel="noopener noreferrer">mitigate</a> climate change, absorbing and reducing the amount of carbon in the atmosphere. Healthy rivers and floodplains help communities adapt and build resilience in the face of climate change by improving flood protection and providing water supply and quality benefits. Rivers are the cornerstones of healthy, strong communities.</p><p>The more than <a href="https://archive.epa.gov/water/archive/web/html/index-17.html" target="_blank" rel="noopener noreferrer">3 million miles</a> of rivers and streams running across our country are a source of great strength and opportunity. When we invest in healthy rivers and clean water, we can improve our lives. When we invest in rivers, we create jobs and strengthen our economy. When we invest in rivers, we invest in our shared future.</p>
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