What Lights To Use For Indoor Seed Starting?

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Most gardeners that want to raise their own starts from seed will eventually want to buy indoor grow lighting for the purpose.  Good quality grow lights are a great investment!

Indoor grow lights allow the gardener to mimic the sun.  This, in turn, allows the plants to grow properly, as they would under the sun.

There are three major types of lighting that are suitable to use for indoor plant lighting.  These types of lights are:

  • Fluorescent
  • HID (or high intensity discharge)
  • LED (or light emitting diode)

This post aims to explain these different types, provide you pro/con information and hopefully help you figure out what kind of indoor lighting might be right for your indoor garden.

Why Does The Gardener “Need” Indoor Lighting?

This is a really good question to start with.  Why do you even need indoor lighting?

Most gardeners understand that plants use the process of photosynthesis in the process of their growth.  Photosynthesis is essentially the process of turning light energy into chemical energy that fuels the plant’s growth.

The sun is a very powerful source of light.  We know that it is very good at sustaining plant life all over the planet.

Plants require a certain amount of that light energy to grow well.  This energy could be measured in terms of intensity, or the amount of power behind that light source.

When the gardener is trying to mimic the sun indoors, it’s important to think about that effort in terms of providing your plants both the light spectrum and energy intensity that it needs.

When you try to grow plants with insufficient lighting, the plant will instinctively “reach” for more light.  The plant “thinks” that if it grows a little bit taller, maybe it can reach the light.

Growing plants under insufficient lighting results in plants that are trying to “reach” for light that simply isn’t there.  This results in plants that become what is called “leggy” – or much taller than they really should be.

Leggy plants are generally considered a poor start for a plant.  Such plants will have a hard time at life and may never be able to recover.  This is the biggest reason the indoor gardener needs appropriate indoor lighting!

Photosynthetic Active Radiation & Plant Growth

A very quick introduction to light would tell you that light, as we see it, is created from a multitude of frequencies.  These frequencies represent, essentially, different colors of light.  What we see as light is actually comprised of many different colors of light!

Research has shown that plants are known to use a light specific spectrum, or frequency, of lighting.  This spectrum is called PAR or photosynthetic active radiation.

When it comes to PAR, this is a more specific range of light frequencies that plants use to photosynthesize.  The spectrum ranges from blue (cool) to red (warm) with green and yellow frequencies in between.

Without delving deep into lighting and specific plant complexities, there are a couple things to know about light spectrum.  Generally speaking:

  • Blue light spectrum is great for vegetative phases
  • Red light spectrum is used more heavily in flowering and fruiting

The sun is a very bright light source.  It is great at providing both plants and humans what they need from a light requirement perspective.

Indoor lighting, however, is most often made for humans, not plants.  That isn’t to say that plants can’t also use that same human based lighting.  What is important, however, is that the plant receives lighting that produces PAR, in sufficient intensity.

Fluorescent Lighting And The Indoor Garden

Fluorescent lighting is one of the most common types of lighting used for seed starting.  Fluorescent lights come in many varieties and sizes that can suit your indoor garden purpose.

These varieties range from the common light bulb format to “tube” varieties that are better at covering a larger area.  Any of these fluorescent bulb varieties will work for plant growth!

This picture shows multiple types of florescent light bulbs, specifically in a tube configuration.  Tube configurations are often ideal for the gardener since they cover more space economically.

Remember what we said above about light intensity being important?

There are also fluorescent lights that are specifically marketed to gardeners.  These bulbs are typically considered “high output” and thus they produce more light than the common household fluorescent bulbs would.

These gardening-specific high output florescent bulbs are usually called a T5 variety.  They have a few advantages over regular bulbs, including:

  • Higher (more intense) PAR output
  • Customized frequency range (more blue vs. red or vice versa)
  • Lower heat output

Most importantly, these high output bulbs are stronger than most other types of fluorescent lights.  This helps with keeping tight plant growth, which results in less “leggy” plants.

Multi-bulb fluorescent fixtures allow you to easily cover large areas, such as as a table that contains seedling trays.  You will generally see two, four, six and eight bulb fixtures available on the market.  More bulbs provide greater light strength and greater coverage area.

Fluorescent Lighting Advantages:

  • Generally less costly than other types of lighting
  • Ease of coverging larger areas
  • Decent energy efficiency
  • Low heat output
  • Sufficient light spectrum for plants

Fluorescent Lighting Disadvantages:

  • Not particularly strong, especially when dealing with thick plant canopies
  • Requires semi-frequent replacement
  • Typically are big and bulky, requiring a lot of space for use and storage

LED Lighting And The Indoor Garden

A relative new-comer to the indoor garden lighting are LED lights.  Though they are relatively recent to the indoor garden lighting market, they do show great promise by providing the gardener some significant advantages.

Originally, LED lights were prohibitively expensive and thus, were more commonly used by cannabis growers.  These days, however, the cost of LED lights have dropped considerably which makes them a practical consideration for general gardeners.

This is a picture of common LED lighting that is specifically marketed towards gardeners.  Modern LED’s often produce “full spectrum” lighting, which makes it look more natural than this older lighting style.

Early generation LED’s were not really that good.  They used small wattage LED’s, which weren’t great at providing light penetration.  Manufacturers also weren’t addressing all of our plant’s lighting needs, providing limited spectrum lighting.

However, the LED lighting market has been advancing at an extremely fast pace.  Newer LED lights are both more effective and have also come down considerably in price.  Manufacturers have started to get really good at making LED lights that are really good at growing plants!

The advantages of LED lighting is optimal energy efficiency and the ability to customize the provided light spectrum more specifically for the plants.  This means that you’re not spending electricity generating light frequencies and heat your plant simply won’t use.  Another advantage is long LED’s lifespans, which means you eliminate bulb replacement costs.  One of the greatest benefits of modern LED lighting is reduced heat that comes from the light fixture.

The disadvantages of LED’s are generally cost, they tend to be more expensive than other types of lighting.  This is usually countered with significant energy savings, however, and often will pay for the difference quite quickly.  Modern LED lights can also be quite powerful, meaning you have to take care when using them with seedlings.

Given our very high electricity costs, we have migrated our lighting to LED systems.  For us, they provide much greater light to watt ratios than other types of lighting.

Notes About Modern Full Spectrum LED Lighting

You will likely come across terms like “multi spectrum” and “full spectrum” if you are looking at LED’s.  The LED industry is moving towards full spectrum LED’s, or natural looking lighting.  If you are considering LED, we also recommend full spectrum LED lighting.

There are many purple/blue/red LED’s on the market.  This spectrum is not natural to our eyes and can prevent your ability to see plant deficiencies and problems.  While these lights will grow plants, the purple color of the lighting can simply be less than desirable.  Full spectrum LED’s provide a more natural light and are superior in this regard.

High Intensity Discharge (HID) And The Indoor Garden

You have seen these types of lights before, they are commonly used in street lamp applications.  They provide a very robust amount of light, stronger than any of the above sources of lighting.

There are two major types of HID lights.  Metal Halide, which provides a cooler/blue spectrum ideal for early and vegetative growth.  HPS, or high pressure sodium, provides a warmer spectrum which is good for flowering and fruiting purposes.

HID lights use what is called a ballast to create the very high energy levels needed to run these lights.  Modern digital ballasts include features like the ability to use both metal halide and HPS bulbs, as well as selectable power settings that will allow you to use less energy.

For most gardeners interested in growing starts, the HID light is a bit of overkill.  However, they will give some of the best results available.  They also tend to more easily cover large areas, such as 4 foot by 4 foot grids, making them an ideal choice for the larger scale gardener.  If you also delve into year round production, they could be an ideal choice for you.

HID lights are usually sold by the number of watts, which is essentially how much energy it will draw while running.  Common values are 150, 250, 400, 600 and 1000 watt varieties.  Bigger is not always better, your specific application and desired footprint coverage will determine the size needed.

Generally, the lower end will cover 2×2 or 3×3 foot spaces, whereas the larger units can cover 4×4 foot and larger.  If you are able to get a digital ballast with selectable power settings, it may be desirable to go a bit larger and dial it down for your needs at the time.

The primary advantages of HID lights are superior light penetration, allowing you to grow full maturity plants with ease.  They also are highly energy efficient, however, they do not give a “perfect” spectrum for plants and energy is wasted on non-essential light spectrum.  HID lights tend to be quite cost effective as well.

The major disadvantages of HID lighting is they tend to draw more energy than other lighting types, meaning your operational costs will be higher.  Also, bulb life is much shorter than other lights, which means you will have to replace them far more often.  Another common disadvantage is they generate more heat than other lighting types.  Sometimes, this additional heat can be an advantage to cool climate gardeners.  The larger wattage bulbs, such as 600 and 1000 watt varieties generate a lot of heat, which often means you have to develop cooling methods to evacuate that heat.

It is common to see HID lights used with reflectors, which will help direct the light energy towards your plant.  Hood type reflectors are usually great for easier cooling, where ducting can be connected to inline fans to evacuate the heat.  Gull wing reflectors are simpler to operate, however, will be more difficult to keep cool.

We have used these types of lights in the past and they are excellent for providing rapid plant growth.

So Many Choices!  Just Help Me Choose A Light!

For a sure fire, easy experience – your best bet will be an appropriately sized fluorescent bulb fixture.  This will be plug and play, relatively inexpensive and energy efficient.  They will be a very reliable workhorse year after year and will get the job done effectively.  Buy the size you need, either 2 foot or 4 foot, depending on the length of coverage desired.  If you need to cover up to 2 foot of depth, consider a six or more bulb fixture.

However, if you are looking to try to save operational costs, LED is definitely going to be your choice.  These have become extremely popular in recent years, which has also brought the pricing down significantly.  As we mentioned above, we have transitioned to almost entirely using LED lights in our gardens.  Eventually, LED lights will pay for the cost differences of other types of lighting and will benefit you over the long term.

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