Guide to Successful Indoor Gardening (Beginner-Friendly Too)

So you’re considering an indoor garden and you don’t know where to start?

First, you should know that learning how to grow indoor plants is not that hard.

All you have to do is follow some simple instructions. And of course, you have to be ready to spend some time looking after your plants.

If you already know a thing or two about growing veggies indoors, head to one of our articles on growing specific plants indoors for more detailed information:

If you know much less and want to start from the basics, you should know that in truth, indoor growing is much different from outdoor growing.

While indoor growing is a bit more complicated and costly to start, it’s worth it in the end.

Having the ultimate sanctuary that you’re able to control, the privacy from prying eyes and the convenience of a grow room are all excellent reasons to opt for indoor growing.

The following is simply indoor vegetable gardening for beginners with a more detailed look at some specific veggies and other plants available above.

As long as you enter well prepared, with the necessary equipment and a clear plan in place, indoor growing can be a rewarding experience, and you’ll have a plentiful harvest to show for it.

Indoor Gardening 101

Small plants sprouting out of ground

Selecting the Environment

You need to select the correct environment.

When thinking about how to grow an indoor garden, my first answer usually is: start with the basics and build uppon that.

This place will need to have electrical outlets, and it will need to be an area where you can easily regulate the temperature.

Having your own grow shed is always nice, but if you can’t manage that, a closet, a spare bedroom, or a well-insulated garage will suffice.

CO2 is very important to the growing process, and this is something you may want to take into consideration when you’re choosing a location for your growing setup.

If you can’t find a place that will offer your plants access to about 350 ppm of CO2, you’ll need to consider adding it into the environment to ensure your plants will be able to thrive well.

Soil vs. Hydroponics

Choosing the medium that will work best for you is half the battle. Indoor grow spaces can be comprised of traditional soil or a hydroponics system.

Both have advantages and disadvantages, and you’ll need to decide which one will work out best for what you’re trying to accomplish in your grow space.

Soil is Simple

Just as you can grow something outside in soil, you can also have a soil garden indoors.

These are better than outdoor soil gardens because they give you the ability to control every aspect of your plant’s growth.

You’ll have a fresh, healthy crop that’s never had to deal with harmful free radicals in the environment, exposure to pesticides or other chemicals, and you won’t have to worry about parasites or animals interfering with your plants.

I think you could ask anyone who owns a regular garden how to grow plants indoors and they will tell you a million things about soil.

Hydroponics is More Expensive to Start

It’s also a little more complicated. Hydroponic systems will produce a plant that is healthier and heartier than a plant you would grow in soil.

This will require more of a learning process when you’re setting up, and the maintenance will be slightly more complicated, but the end result is worth it.

You’ll have higher quality, better tasting harvest that’s been boosted to its maximum potential.

Nourishing Your Plants

You can’t just set your plants up and forget about them. They need food to grow, and they get that from the nutrients you’ll need to provide for them.

Soil growth is a little more straight and to the point. There are organic fertilizers and growth compounds that you can treat your soil with to make sure they’re properly fortified as they grow.

All plants require both micro and macronutrients. Macronutrients are the bulky nutrients that your plants will need the most of if they’re going to grow strong.

Micronutrients are minor nutrients that you will use to supplement your plant, and what micronutrients you use largely depends on exactly what you’re growing.

With hydroponics, nutrients work differently. You might have heard of NPK, which is a cocktail of nitrogen, phosphorus, and potassium.

This is the main compound that will feed your hydroponic grow project, but you’ll still need to supplement with micronutrients throughout different growth stages or to adjust the way your crops are developing.

Getting the Right Gear

You have to replicate nature inside. A normal lightbulb and a good medium will never be enough to keep your plants going strong.

You need to set the stage for your plant’s development by adapting the environment to meet its needs.

Lights are important.

You need to trick your plants into believing they’re getting sunlight, and it takes a special lighting system to do that. While there are a variety of lights you can use for an indoor grow project, LED lights are by far the most efficient.

Read our complete comparison of LED vs HPS grow lights (both very popular among indoor growers) to really see where each grow light thrives.

Other lights are hot, bright, and use a ton of electricity. With good LED lights, you won’t have to work as hard to keep the environment at the right temperature, and you have the added benefit of a full spectrum of blue and red that accurately duplicate the sun’s spectrum.

You’ll also need some kind of exhaust system to circulate the air properly. You don’t want to let the heat build-up in this area, as it will damage your fragile crops. Keeping the temperature right is crucial. Too hot, and your plants will become dry and brittle.

Too cold, and you’ll start shedding crops that aren’t fully formed.

If you’re growing something that you don’t want anyone to smell, consider getting a decent carbon scrubber. The carbon scrubber will eat the odor before it has a chance to travel and invoke everyone’s curiosity.

These are great for staying low key and upholding your privacy.

As mentioned previously, a CO2 system is also a wise investment. If you want your plants to flower well, they’re going to need a little extra CO2 to produce large blooms.

You’ll also need to investigate your mediums. Hydroponic systems are the best way to go, and there are several varieties. Make sure you’re choosing a hydroponic system that’s in line with what you’re trying to accomplish.

How Often to Water Indoor Plants?

Green Thumb School Lesson 101 should be a course on watering plants.

This basic necessity is one of the first things every indoor gardener should master if they are growing plants in soil. (If you grow hydroponically or aeroponically, you ca skip this section)

Watering plants is simple if you have a few pieces of knowledge beforehand. Three basic considerations are:

Plant Variety

Not all plants should be watered on the same schedule, with the same amount of water in the same environment. Some plants are resistant to dry conditions or ‘drought resistant‘.

Other plants need a lot of water only during very specific times in the growth cycle, like corn, which should be given ample water when the tassels of the cobs form and when the cobs begin to grow.

Do a little research on your particular plant. If you are growing vegetables The Old Farmers Almanac has a handy watering chart you can reference.

For traditional houseplants, the below chart shows which plants you should allow to dry out before watering might be helpful.

Plants That Purify Air Chart

Growing cannabis, a common indoor crop, should be watered when the leaves start to droop.

Marijuana should be allowed to dry out just slightly, before watering again. Poke a finger into the soil about an inch deep. If the soil is dry, it is time to water. If the soil is wet, do not water.

Water the plant until a small amount of water comes out of the drain holes. It is better to underwater than overwater a cannabis plant.

Container Size

Small pots and containers will dry out faster and need more frequent watering than large pots.

However, a small pot needs relatively less water per watering. In a nutshell, the size of your pot will dictate the frequency of the watering.

Amount of Light and/or Heat

The amount of heat, light and moisture content in the air will factor into how much water your plant needs.

A plant that gets a lot of light. Or is in a dry or hot climate will need more water than a plant of the same type in cooler temperatures or a climate with more ambient moisture.

Many plants need less water in the winter, but if you use a heater to warm your house, or you have a heat source for the plants, they may need more water.

Small Indoor Grow Room Setup (How To Design It)

Young tomato plants

Successful indoor gardening relies on controlling the environment of the grow space. Take into consideration the following aspects during the setup of a small indoor grow room space.



Most plants like between 40 to 60 percent humidity, but the ideal humidity can change depending on the stage the plant is in, or type of plant.

Marijuana prefers a humidity of 40 to 70 percent during the veg state, but only 40 to 50 percent during flowering.

In contrast, the habanero chile does best in high humidity, and a hot environment, but will not tolerate damp soil. It is important to research the specific plant you intend to grow.


Plants grown indoors are comfortable at temperatures that we are comfortable with, usually between 65 to 80 degrees, depending on the specific plant.


Plants use CO2 to grow and like levels between 300 to 400 parts per million (PPM). We will discuss this in the next section.


Good ventilation helps regulate temperature, assists in achieving desirable levels of CO2 and humidity, and eliminates odors that certain plants, such as cannabis, create.

A ventilation system usually consists of an oscillating fan, Extraction Fan, ducting and a carbon filter to remove odor.

Growth Medium

Soil, hydroponics or Aeroponics are all growth mediums discussed previously.

Water, Fertilizer and Nutrients

Plants need to be fed. Water is the most crucial nutrient. Good water must be free of chlorine and fluoride.

Consider a water filter in your indoor grow room. Water must also have the correct pH and balance of mineral salts to optimize the growth of plants and you need testing tools to regulate the water.

  • Primary Nutrients: NPK, Nitrogen, Phosphorous, and Potassium are the primary ingredients in most fertilizers.
  • Secondary Nutrients: Calcium, magnesium, and sulfur, help with the structure of the plant cell wall, production of chlorophyll, formation of amino acids and root growth.
  • Micro Nutrients: Boron, Chlorine, Copper, Iron, manganese, molybdenum, and zinc are needed for fruit and seed growth, plant metabolism, photosynthesis, nutrient uptake, enzymatic action and more.

Grow Lights and Timer

Grow lights are a key consideration of any indoor grow project. Grow lights are also a controversial topic with various opinions on what type of grow lights are best.

(Usually, from what we’ve seen around the block, LED grow lights are best. Of course, it depends on the plants you’re growing)

Testing Equipment

A pH meter is used to test the water and is especially important if you chose hydroponics as your growth medium.

A conductivity meter is also crucial for a hydroponics system to make sure the mineral balance is correct and that you are not under or overfeeding your plants.

There are meters available to test your indoor grow room humidity, CO2 and air circulation, as well as a thermometer to measure temperature.

Stakes, Supports and Trestles

You want to think about and anticipate plant growth and give the plant the structure and space it needs to grow. A plant that grows as a vine may need a trestle.

Cannabis plants will also benefit from trellising, tomato cages or steaks to support the plants’ heavy limbs.

Pest Control

Pests, insects, plant disease and fungus are all a possibility with an indoor grow garden, and they can devastate your crop. Think ahead and decide how you might combat these problems, and be vigilant by checking the plants regularly for problems.

Consider natural and organic methods such as the use of beneficial insects like ladybugs or the Minute Pirate Bug which not only has a cool name but is incredibly useful in eating problematic pests.

Consider Supplementing CO2

Carbon dioxide is the most important building block your plants use to grow, flower and produce fruit.

Plants that grow outdoors, where air circulation is good, get enough CO2, but plants in small indoor gardens often do not get enough CO2.

In a small enclosed space, plants can use up much of the CO2 present and end up lacking this essential element.

Plants low on CO2 have long limbs with fewer leaves and fruiting potential. These plants are thin and delicate, yielding smaller fruits.

A CO2 tank and CO2 burner are the most common ways to add additional CO2 to your grow space.

A tank poses certain security risks and buying one could possibly draw unwanted attention. A CO2 tank will also need to be replaced, which is inconvenient.

A CO2 burner uses a flame that poses a fire hazard and the flame adds heat to the grow space. However, a CO2 burner is the preferred choice for growers who need supplemental CO2.

Too much CO2 can also damage plants, so a CO2 monitor is critical when using a burner or any supplemental CO2. There are monitors available that integrate into CO2 generators and turn the system on and off when the CO2 needs to be increased or decreased.

CO2 falls to the floor so you must have a way to circulate air, such as an oscillating fan. It is also important to note that you only want to add CO2 in your grow space while the grow lights are on, or in the on-cycle.

Many CO2 burners are designed to hang above the plants, so you need an appropriate structure in place to hang this equipment.


Once your room is finished and all of your equipment is set up, it’s time for you to get the ball rolling. As you go, you may discover modifications you want to make or additional things you’ll want to purchase in order to help your project run smoothly.

A lot of trial and error is involved in setting the right circumstances for an indoor grow space, so don’t let yourself get discouraged.

Andy Gibson

My name's Gibson. Andy Gibson. I like to think of myself as the Bond of the backyard, that is if yard work ever became sexy. I write about everything about indoor and outdoor gardening and the dread-it-but-still-need-to-do-it chores around the yard, like cleaning out the gutter guards.

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