Why Do Plants Grow Faster in a Greenhouse than Outside

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Whether your interest in a greenhouse stems from wanting efficient crop production or you’re just trying to figure out what a greenhouse even is, you’ve come to the right place. Greenhouses offer a controlled environment for your plants to grow and flourish under your care.

So, do plants grow faster in a greenhouse than outside? A greenhouse acts as the best solution for optimized plant growth. Some plants have a strict growing regimen or are very fragile against pests and weather conditions. Greenhouses are also a great way to extend the growing season, so you can keep harvesting continually producing crops.

Whether a greenhouse is a smaller lean-to hut or a larger high-tech building, they’re still beyond capable of helping your plants grow.

What is a Greenhouse?

Let’s start with the basics. A greenhouse has four walls and a roof, typically transparent, made of glass or fiberglass. It’s a building in which plants such as trees, bushes, vegetables, and flowers can be grown. There are different types of greenhouses, ranging in sizes and purposes, but it all comes down to helping your plants grow effectively.

Different plants require different growing conditions centered around:

  • Humidity
  • Temperature
  • Soil
  • Water
  • Sunlight

Growing in a greenhouse with set conditions will help your plants grow. A greenhouse is a typically enclosed space, and the transparent barriers are able to trap heat from the sun, creating a warmer internal temperature than the air outside the greenhouse.

Supporting the Plants

What Your Plants Need

Just like people, plants require the basics for survival: food, water, and air. These three requirements are the same for nearly all forms of life. Plants get their food from sunlight through photosynthesis, their water from your watering cans, and their air from the carbon dioxide found throughout the atmosphere.

And like people, plants need more than just the basics; they also require shelter, suitable warmth, and the right level of humidity for growth. This is where a greenhouse comes in. Having four walls and a roof over the plants prevents many negative weather conditions from affecting your crops. A fully-fledged greenhouse does this and more. It discourages the negatives and embraces the ideals.

Ideal Conditions for Plant Growth

A greenhouse offers what the outside cannot, a controlled environment. Plants like lettuce and garden beans take around two months to grow, while pumpkins and potatoes take their time, requiring four months for growth and harvest. A lot can happen during the months when the plant is still growing: A bad rainstorm, a cold day in spring, or a deer walking through the garden, well. It’s not quite ideal.

Having your plants grow in this enclosed area, the greenhouse, allows them to grow in peak condition. Controlled water and soil levels, a consistent temperature, and no pesty animals chomping on your lettuce add up and allow the plant to focus on its growth, so the plant can use its energy towards production rather than protection.

All these benefits a greenhouse provide are the reasons why plants grow faster in a greenhouse than outside, not only do they grow faster but also healthier.


The majority of plants, crops, or flowering plants, require between 50-70 percent humidity in the air. This can be achieved through proper heating, ventilation, and temperature systems. Setting up fans, vents, humidity controllers, and such are important ways to keep the greenhouse’s humidity in check. A greenhouse, having its many pros, comes with high levels of upkeep that are overall worth the effort.


If you’re growing plants within a greenhouse, odds are you’ll want to keep it nice and toasty inside. The ideal temperature within a greenhouse is around 80 degrees Fahrenheit. The heat from the sun’s rays will do a fine job at heating the greenhouse. During sunny days or an extra hot stretch in the summer months, regulating the greenhouse’s internal temperature is especially important. A ventilation and fan system can be built to do just that.


Just like plants from the outside world, plants grown in a greenhouse require soil. It allows the plant access to the nutrients within the soil, such as nitrogen, phosphorus, and potassium, three important nutrients just about all plants require.

Different plants have different ratio needs of nitrogen, phosphorus, and potassium, so soil-based mixes consisting of compost and potting mix are key to a plant’s growth.


A plant needs water in the same way a person needs water – without the right amount it will not grow properly. The chemical equation for photosynthesis – a plant’s way of making its food – involves air, water, and light energy. Too much water will drown a plant, too little, and photosynthesis will not occur to its full extent.

While plenty of plants can grow on their own in the wild, you’re looking for your homegrown plants to flourish. A well-controlled watering system in a greenhouse will cut back on the time it takes to hand-water each individual plant. Sprinkler systems and an irrigation method would work, depending on the space you have to work with.


Plants require light energy for photosynthesis to occur. However, sunlight is not a constant throughout the day and year. The winter months have less sunlight than non-winter months, so light is a hot commodity for your year-round greenhouse plants. Setting up an artificial light system, called grow lights, for your plants is a great solution to this dark problem.

Often taking the form of LED lights, a quick image search confirms both the usefulness and the stylish nature of these bright, colorful grow lights!


As plants inhale carbon dioxide and exhale oxygen, they naturally produce moisture with it. This could end up producing mold which is harmful to your plants. Having a well-ventilated greenhouse will keep air flowing and prevent moisture buildup. By keeping the air flowing, this prevents the air inside the greenhouse from overheating and damaging the plants. Just like people, plants can get heatstroke!

Ventilation is incredibly important for the care of your plants within a greenhouse. Non-flowing air is the perfect condition for plant-based pathogens and fungi to thrive. By having the right level of airflow, clean air can continue to enter the greenhouse, discouraging plant disease. Fresh air isn’t just combative against disease, it’s also a requirement for plant growth.

Plants need fresh air, they aren’t able to survive on stale, stagnant air. As air is needed for both the plant’s carbon dioxide requirements and photosynthesis, this makes ventilation very important for your plants’ growth.

Tending to Your Garden

A garden requires care and love, so odds are you’re outside just about every day weeding, watering, pruning, the list goes on. Unfortunately, Mother Nature doesn’t seem to care about your daily plans – it’s hard to keep track of your garden’s needs when it’s rainy and windy. Bad weather delays your gardening plans and can even uproot or destroy your plants.

Having your plants grow inside a greenhouse removes these issues from the equation and adds up to a happy, healthy garden.

Opposing the Problems

Outside weather conditions can fluctuate. While you can hear about this on the weather channel and bundle up appropriately during warmer months, your crops don’t have that luxury. Of course, there’s the option to cover any plants outside with mulch or a sheet-like shield, but that isn’t a perfect solution. And it’s a bit of work involved when you only have a few days to prepare for the coming cold.

With a greenhouse, temperature and humidity are consistent year-round, so worriedly watching the weather reports would become a thing of the past. You could spend your mornings for yourself, rather than scrambling to put together a DIY solution for those plants outside.

Heavy rainfall can dislodge the soil in your garden, wash away nutrients, or even flood and damage your plants. Having your plants grow in a raised section of your greenhouse or even a garden pot removes this worry from your agenda. Each plant would receive its ideal level of the soil to nutrient ratio and pH levels as well.

A garden can face more organic problems than just weather – pests come in all shapes and sizes when it comes to your crops. Odds are, your enclosed and protected plants won’t have the opportunity to come into contact with many aphids or moths.

A greenhouse requires ventilation for pushing oxygen and carbon dioxide in and out of the building, so there’s always a chance of smaller pests slipping through any cracks. A few bugs are still better than a whole horde of them. If you were to spot harmful insects in your greenhouse, removing them from a controlled area is far easier than warding your whole garden space against dozens of different pests.

A Better Yield

Perhaps you’re in a region with a growing season that’s not ideal for your chosen plants. Different plants are best suited for different regions of the world depending on that area’s climate. You could be located in an area with extremely hot weather, but you’re in the mood for some carrots, which grow best in cooler temperatures. Or the opposite could be true: You’re in a chilly area but need home-grown sweet potatoes, which grow best in a hotter climate.

Either way, you can’t simply stick the seeds outside and hope for the best, these plants need some care! This is where you come in. Tending to your greenhouse’s garden daily and monitoring your plants’ conditions lead to a successful harvest if you nip any problems in the bud.

Perennial Planting

Many plants are classified as annuals – they take a season to grow and then they die. Perennials, however, are plants that live for two or more years. Many popular flowers, such as lavender and peonies, are perennials. Even some fruit and vegetable-producing crops, strawberries, potatoes, basil, apples, to name a few, are perennials as well – the main plant, bush, or tree will survive many years and will yield throughout its life cycle.

Perennials planted outside face the dangers previously mentioned – pests, frost, and negative weather conditions. While you have the option to move them inside when the weather gets bad, there are still bugs and other animals to worry about. It’s simpler to just grow your perennials in a controlled environment: your greenhouse!

Continuously Producing Plants

Grown to its adult, yielding stage, certain plants will produce many times throughout their lives. Hot pepper, tomato, and cucumber plants will produce a few times while they’re alive. These plants tend to die when their season is over and conditions are no longer ideal for their survival. It’s better to just grow these crops in a greenhouse to begin with. Starting sooner and ending later in the year results in a greater yield from these producing plants.

Different Types of Greenhouses

Maybe you already have a fully-set-up greenhouse, or you might be considering getting a greenhouse for your backyard – but don’t try starting up a commercial-sized building from the get-go. The world’s largest greenhouse, known as The Eden Project in the United Kingdom’s Cornwall, isn’t something to immediately set out to build yourself.

What’s in a Greenhouse?

(Frame vector created by macrovector)

Greenhouses first and foremost are built to house plants. Beyond that, it needs the basics for planting and gardening: soil, mulch, gardening tools, seeds, and the like.

Depending on what type of greenhouse you’re looking at, you could set up shelves for potted plants, a space set aside for any tools, ventilation panels along the walls and roof, even an automatic misting system – like the ones you’d find at the produce section in a grocery store.

Greenhouses, despite all serving the same purpose, can look however you want. There’s the option of going traditional, making a boxed, shed-like structure with four walls. You could follow The Eden Project’s style, going for geometric shapes in a modern style.

Pictured above shows four different greenhouse styles, all with their advantages.

  • Lean-to greenhouses offer a solid wall upon which the greenhouse rests, offering further protection against the elements and less risk for your plants. They also take up less space in your yard, letting you customize the rest of your living space.
  • Gable-roofed greenhouses offer more space in your greenhouse for moving around, giving you personal comfort in your garden area. The design of the roof allows for more sunlight to give your plants what they crave.
  • Tunnel greenhouses are constructed with arches rather than the straight lines seen in the lean-to and gable-roofed greenhouses. They’re typically cheaper and the curved roof reduces condensation.
  • Small greenhouses are seen commonly covering groups of plants, rather than as a whole building containing the plants. Plastic water bottles, glass coverings (with adequate ventilation), or even just a mini, well-built greenhouse will suffice. It requires more upkeep and daily care, and you wouldn’t be able to walk inside. But for those with smaller or no yard, don’t throw away this option.

Getting Your Greenhouse

Getting a greenhouse can be as simple as going online, seeing something well priced that looks nice, and clicking that “add to cart” button. Wait a week or two, and you’ll get that package in the mail. One greenhouse, ready for varying levels of assembly and those heirloom tomatoes, good to go!

Well, not quite. Different garden or plant requirements mean looking into many different types of greenhouses. You might be looking to get a larger greenhouse to start, with room for moving around or even a small, fruit-producing tree, but that’ll require extra assembly than simply attaching some poles.

Maybe you’re just looking for a smaller lean-to greenhouse, attached to your home or garage. Made of glass, wood, and the occasional screw here and there, these greenhouses are smaller but no less effective for your plants’ growing needs.

You could start even smaller, going for a greenhouse that’s portable with handles and made of plastic, designed for basil or other potted plants. Where you start on your greenhouse journey is up to you.


Greenhouses act as an enclosed, controlled mini-environment for your planting needs. Different types of greenhouses are suitable for different plants. A greenhouse requires lots of upkeep, but having your plants grow and thrive is worth the effort you’ll make for your garden.

Having a controlled environment cuts back on outside influences harming your plants. No more windy days uprooting your crops or that stray deer munching your prized heirloom tomatoes! A rainy day won’t be a deterrent for you tending to your plants either, your greenhouse is rather an escape from the dreary weather.

Plants need several things, such as sunlight and correct humidity levels, to thrive in their environment. A ventilation system is a necessity for a larger greenhouse, to maintain fresh, flowing air inside the greenhouse. This decreases the chances of the development of plant disease or fungal growth.  An extension to the growing season will give plants extra weeks of growth and development.

This all leads to a greenhouse creating the optimal growing conditions for your plants: the perfect temperature, soil levels, and optimal carbon dioxide levels for the plants (well, definitely not for people, so no long naps in the greenhouse, please!).

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