Gardening Indoors with Lights

Craving the taste of a fresh, homegrown tomato in the middle of winter? Tired of store-bought greens that barely last a few days? If outdoor gardening feels overwhelming, there’s a simple solution—gardening indoors with lights. With the right setup, you can enjoy vibrant, nutrient-rich produce year-round, no matter the season. Let’s explore how easy and rewarding it can be!

Making a small investment in a good grow light can make a world of difference in what you can accomplish as an indoor gardener. 

Shop the Happy Leaf LED Grow Lights Store →

While many people are familiar with what a shop light does for seed starting in the spring, we consistently talk to people who are not familiar with what today’s advanced LED grow lights can bring to the table for an indoor gardener. Shop lights and even many of the LED grow lights available on Amazon simply fall short of offering optimal light levels for plants to fully mature, e.g., spinach, herbs and tomatoes.

For this article on indoor gardening, we are primarily focusing on growing food or edible plants, but indoor gardening can encompass any plants that someone wants to enjoy year round – and the same statement holds true – that a good quality grow light makes a difference in how well plants respond.

The Kratky Method: A Soil-Free Solution for Gardening Indoors with Lights

Combine a good grow light with a mind-blowingly simple method called the Kratky Method, (aka, passive hydroponics), and you will wonder why everyone hasn’t become an indoor gardener.  It’s crazy how easy this is, and it can easily pay for itself in a short period of time with the savings on herb and spinach prices alone.

So some people have taken the plunge and purchased AeroGarden-type setups or Tower Garden systems because they want to experience the benefits of indoor gardening – and these systems can work out well.  However, we hear many people find them either limiting or complicated to work with, and once they see the Kratky method, they realize they can do so much more with fewer resources.  Another issue with these setups is the lighting is rarely up to  the job of growing the types of plants that make a stellar indoor garden.

Very simply, the Kratky method is a soil-less way of growing in mediums such as clay pellets, rock wool, or coco-coir and vermiculite.  At our home, we discovered this method because we started to have gnats showing up in great numbers when we used potting mix to grow indoors. Once we learned the method we said this is the only way to go and now we have taught thousands of people how to do this and they are simply delighted with how easy it is.  The Happy Leaf LED YouTube channel is a great place to see step by step how we plant seeds and grow many varieties of food – even eggplants or edible flowers.

Let’s quickly talk about microgreens as well.

These little beauties are really superstars for indoor gardening because they pack a lot of flavor and nutrition into a very adaptable plant that can be added to soups, sandwiches, sauces, pizza, tacos, and to garnish just about anything!  Talk about bang for your buck! A tray of microgreens that can be grown in 7 days can sell for as much as $25 at a farmer’s market using less than $1 in seeds per tray. Each variety of microgreen has its own unique flavor, be it broccoli, kale, sunflower, peas, radish, arugula, turnip, mustard green, etc.   The flavors are quite vibrant and the nutritional punch is formidable.  The USDA states that microgreens have five times the nutritional content of their mature counterparts. 

What Are the Best Plants to Grow Indoors with Lights?

It’s possible to grow just about anything indoors if you have the patience, space and, of course, good light.  The best things to start with are either lettuces, basil or your favorite herb, or microgreens.  Personally, we love the spinach we grow indoors and think we’d miss that the most if we didn’t grow it all the time. 

We continue to experiment with seed varieties to find the flavors we like and types of plants that are best suited to indoor gardening.  For example, we recommend only choosing determinant tomato plants so the plant stays relatively compact.  We also recommend working with cherry tomatoes or tomato varieties that are small to medium sized and not trying to grow the beefsteak types of tomatoes. 

As for lettuce we favor the varieties mascara, black seeded Simpson, and crisp mint. We also love tender baby arugula.

Kale, don’t forget Kale!  Lacinato is our personal favorite.

With spinach, we primarily grow the Corvair variety but we also like Bloomsdale Longstanding.   Spinach does best in a mix of 70% coco coir and 30% vermiculite versus the clay pebbles that we grow lettuce and herbs in typically.  We have decided to keep 4-6 14” round containers of spinach going at intervals so we can harvest it very regularly.

When choosing plants that flower, you want to go for seeds that are developed for container gardening because these plants are more likely to be compact. With these tomato varieties we haven’t had to worry about pollinating them ourselves:

• Tiny Tim Tomatoes
• Red Robin Tomatoes
• Sweet N’ Neat Tomatoes
• Cucumbers – Quick snack ( choose parthenocarpic varieties)
• Eggplants and zucchini- can be grown but you will need to hand pollinate them.

Choose Your Grow Light Wisely

Hop on Amazon and you can easily be overwhelmed by the sheer number of grow light options.

There are many misconceptions about grow lights, so first let us highlight some of these issues:

First of all, our human eye simply cannot accurately determine the quality of an LED grow light.  Simply being bright tells us nothing.  Nor does seeing a red or blue cast from a light.  Today, any grow light that still has a strong “burple” appearance is giving itself away as having outdated LEDs.

Blog Post: What You Really Need to Know About Grow Lights →

Similarly, just because a light is longer doesn’t mean it will take care of a bigger grow area space.   In this case, the 33” wide light has a wider beam angle and more energy and would do a more effective job of covering a 4 ft wide 18” deep shelf.

Many of the lower priced LED grow lights found on Amazon primarily rely on using white LEDS or outdated chip on board technology.  These lights are built in extremely large quantities which results in a glut of older technology that sits in inventory until it is sold.

Grow lights with fans integrated into them definitely look serious.  In truth, most grow lights that cost under $500 a unit with a fan are very likely using outdated technology

Also, a high quantity of LEDs doesn’t necessarily translate into a more powerful grow light.

The term “full spectrum” sounds good as well, but there are still wide discrepancies in the results we see in various full spectrum grow lights.

Watts, kelvin or lumens are commonly used to describe a grow light’s effectiveness.  Unfortunately, these terms are inaccurate at a minimum and are more often misleading.  The most accurate measurement for understanding what a grow light can do is the PAR measurement.  PAR stands for photosynthetic active radiation. Don’t worry though.  It doesn’t have to get any more complicated to understand what you need to know about grow lights.

Just know that if you are able to get a PAR statistic for the light, you are already able to make a better decision.   In very general terms, to grow the widest variety of plants to full maturity, including flowering, you need to have a PAR measurement over 200 micromoles per square meter per second.  

Even if you can’t find or easily understand what the PAR measurements are for a grow light, the instructions or specifications should at least tell you how much area is covered and what type of growth is supported.  A key differentiator is whether the light supports fruiting and flowering plants.

A Little More About PAR

On a basic level, PAR represents how plants see light, which is entirely different than how humans see light. PAR energy is measured in the number of photons per square meter per second.

PAR measurements are primarily expressed in micromoles per square meter per second, and can get a little confusing to understand especially since there are a number of different choices to express this number including the scientific symbols.  But as we mentioned, you don’t really need to have a deep understanding behind this measurement or even a PAR meter.

Typically, professional grow lights often provide a PAR Map to explain exactly what PAR measurements are reading relative to the coverage area and the distance of the light.  

When choosing a grow light, it is important to know what you will be growing so you can be sure to get enough PAR energy from the light.

Here is a basic guide:

Microgreens and seed starting need 100 to 200 PAR

Vegetative plants need 200 – 400 PAR

Fruiting plants need 300 – 600 PAR

Efficacy and Spectral Graphs

Better quality grow light spec sheets will provide an “efficacy” measurement.  The efficacy is measuring how much useful light is emitted for plant growth for the amount of energy being used.  The higher the number, the better.

At this time, a good number to see is 2.5 (μmol/J)

Many consumer grade grow lights are 2.0 (μmol/J) or less or they don’t even mention their values.

A spectral graph can also be very informative as it will specify the balance of red, blue and green light that is used for that specific light.  Research at leading universities has confirmed there is an ideal ratio of red, to blue to green light to achieve maximum plant growth.  The ideal ratio is 70% red, 10% blue, and 20% green light.

These images are from research done by Professor Erik Runkle at Michigan State, comparing the results of the same intensity of light by varying the red, blue, green colors.

The difference in delivering the optimal type of light to plants shows up not only in the size of the plant, but also the nutritional value, the taste, and the overall health of the plant.

A very noticeable impact with high quality LED grow lights is how quickly growth is seen.

Start Growing Indoors Today

With the right grow lights and techniques, indoor gardening becomes simple, rewarding, and cost-effective. Whether you’re a beginner or an experienced gardener, Happy Leaf LED lights provide the tools you need to grow with confidence.

Ready to begin your indoor gardening journey?

Explore Happy Leaf’s LED grow lights and start growing smarter today!