Greenhouse Gardening For Beginners – Where do I start?
Table of Contents
Have you installed your greenhouse and are you now thinking about growing in it, except that you have no idea how? Do you imagine harvesting your own homegrown fruits and vegetables, but just don’t know where to start? Are you looking for a beginner’s guide to greenhouse gardening? Then we got you covered! Trial and error can be an essential ingredient of the learning process and patience is indeed power. With this compiled Greenhouse Gardening for Beginners’ manual, you will discover how to manage a greenhouse efficiently.
We understand that you have numbers of puzzles in mind. Slow down. We can assist you along the way in your journey.
Growing in a greenhouse can be so much fun for beginners and experienced gardeners alike but before you pick the plants you fancy to grow, examine and research what conditions, temperatures, and moisture your plants will require to flourish. This is a crucial step in order to make your plans thrive.
Easy plants for greenhouse starters
So what should you start with? What can you grow in a greenhouse? The answer is simple: Literally everything. But there are some plants that thrive easier than others. Begin with these simple plants and develop your knowledge in order to make your first experiences:
- Leafy greens like lettuce
See all easy-to-grow greenhouse plants here!
Our easy-to-master pointers below can assist you in how you can use your greenhouse’s potential at its best. Take advantage of every equipment and accessories and it will give you numerous ways to make use of your greenhouse.
By following this basic Greenhouse Gardening for Beginners Guide, you will be more successful and face fewer difficulties – including those on temperatures, insects, water, food, space, light, air, and soil. If you are fresh to gardening, do not be extremely aggressive. Take it one step at a time. We have prepared simple tips for you to start your green thumb journey.
The Essentials for Beginners – Greenhouse Gardening 101
1. Starting seeds
A greenhouse is an excellent controlled environment, especially when you need to extend the growing season for seasonal plants. You can even grow certain veggies all year round. But again you may still be wondering, “Where do I start?”. Now let’s start with seeds.
Starting seeds normally happens in plain level seed trays, hydroponic trays, or single plug trays. They are prepared depending on their particular needs, for example, they may be immersed overnight, stratified, and then set in trays inside the greenhouse.
To do this, you need to understand the following greenhouse gardening basics for seasonal crops:
- Be seed smart
- Get a listing of what you’d wish to plant
- Invest in containers
- Get sterile soil to prevent plant diseases and pest infestation
- Add fertilizer to your soil
- Always water your plants as recommended for each individual plant
- Check if your climate can handle these plants
- How much sunlight are you getting
For beginners, it is important to identify the label and date per seed planted and record entries on the seed packets to recognize the plants easier. Start a little and allot your time to the seeds properly. Review the germination rate on the seed pack to decide how many seeds will provide you with the expected quantity of seedlings.
Hybrid seeds are a healthy option because they are accessible at any garden stores. They are generally identified as F-1 by seed companies. Hybrids crossbreed two similar plants. Here are some more pros and cons of planting hybrid seeds:
- They are bigger and healthier plants that look more identical.
- They have greater and more consistent production.
- You can harvest earlier than expected with improved yields.
- They are not really influenced by ecological stress, pests, and diseases.
- They are more expensive compared to other seeds.
- Seeds from hybrid plants cannot be stored longer.
- Some assume that the result is not that appetizing.
- They will not be like their parent plant.
Heirloom seeds are gardeners choice. You simply cannot defeat the flavor of heirloom vegetables. Heirloom types were produced particularly for their awesome flavor.
- They produce a genetic variety for future cultivation.
- The seeds are usually adjusted to the local environment.
- They are passed on for generations.
- Great for seed swaps.
- Gardeners can keep the seeds for another year.
- They are stable.
- Your plants will not be quite like each other.
- The cross-pollinated species must be separated.
- Unusual plants must be removed.
- It is difficult to buy some varieties in some stores.
- There is no hybrid vigor.
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Seed labels and their meanings
The government expects that every seed set that is offered for sale should be accurately labeled. It helps you buy the best quality that will satisfy your needs.
These seeds are also called true-to-type which will produce a true plant. It means that they will generate plants that are related to their parent plant which is essential for seed conservation.
These seeds came from plants that followed the USDA organic standards of a certain territory or region.
These seeds are not grown with “recombinant DNA technology”. Non-GMO seeds are developed through specific or random pollination.
GMOs cross genes from separate plant kingdoms. Any type of seed can be GMO or open-pollinated, hybrid, and heirloom unless it is approved organic or non-GMO.
Percent germination (germ)
This shows how many seeds will sprout easily.
These seeds that don’t develop readily because of a thick seed coat.
These seeds don’t sprout readily because it needs a pre-treatment or weathering.
2. Temperature control
Another lesson for greenhouse gardening beginners you must learn revolves around temperature control. Identify precisely what is happening inside your greenhouse.
You already have a head start with controlling the temperature of your garden by just using a greenhouse, however, no matter what you are growing you should consider getting an electric or gas heater to extend your growing season through the winter months or an Evaporative Cooling System to make it through the summer months depending on where you live.
In warmer months, you must keep it cooler in order for plants to survive. Moisture within a greenhouse is nearly always close to the peak due to the volume of greenery. Leaves generally perform a method called transpiration, in which they discharge moisture within the environment from pores in their exteriors.
It is essential to convince your plants that they are in a different climate. Greenhouses are intended to trap the warmth from the sun. If no one modified the temperature, it would keep rising or falling depending on the weather.
Its own environment is uniquely dependent on you. You should ensure that whatever heater/cooler you decide to acquire is economical, to keep your bills down.
Evaporative cooling helps regulate temperature and operates to add moisture back. It works perfectly in environments where the atmosphere is hot and dry similar to places like Arizona, Colorado, and California. Have a look at our evaporative cooler here!
A heating system needs to be effective to sustain the desired temperature throughout the daytime and nighttime. A programmable heater with automated timers is required if the temperature normally drops below a particular period. Gardening experts also advise that these heaters are useful for propagating seeds and seedlings in cold weather. You can even opt for propagating heating mats to further cut down on your energy bills. Learn more about the best greenhouse heaters here!
There are some things a greenhouse cannot achieve. One of them is making days lasting. Most of your plants require light to flourish because the light is vital for photosynthesis. But not every light is alike. You should analyze the following aspects:
- The variety of plant being grown
- The season
- How much daylight is achievable
Plants react in a different manner to the intensity and span of light. As plants develop and grow the number of leaves, the demand for light rises. Most of the light utilized by plants is in the noticeable light spectrum. Red and blue colored light are the wavelengths of light most widely used in photosynthesis. They are ingredients of white light or sunshine. Numerous man-made light sources have diverse color blends that may or may not suffice the photosynthetic requirements of your plants.
In summer and late spring, your greenhouse should receive adequate light for plant germination and growth. However, if you wish to plant in winter or late autumn, you might want to invest in an additional lighting system.
LED grow lights and fluorescent lamp strips are high output lighting products that will serve you well in this regard. They are a crucial element to photosynthesis and satisfactory plant germination. They are particularly effective because they will cover a larger surface area and output the full spectrum of light your crops require.
Supplementing grow lights is the best alternative if you live in the North and don’t receive several hours of winter sunlight. Application of grow lights to extend the day’s period will be very beneficial. Whether you simply need to provide your specific plant a boost, or you intend to grow right over the winter, this will be an excellent choice.
Fluorescent lighting is commonly used in the greenhouse simply when a weak natural light is possible. It is applied in propagating spaces or germination room that experience no natural light.
There are certain watering systems and techniques depending on your plants but the basic rules of greenhouse gardening for beginners dictate that you understand the water requirements of every plant you intend to grow. Instead of watering your crops using a general timetable, learn what is required to ensure you do not over or under-water your crops.
Signs of inappropriate watering include irregular drying, decreased shoot, and root growth and immature plants with bad quality and shelf life. This can also increase the usage of pesticides and growth controls to compensate for incorrect watering routines.
Not every plant wants the same volume or frequency of water. Over or under-watering can make plant dilemmas. Overwatering doesn’t happen when your plant is given huge amounts of water at a time. It happens when water is done too often before the soil has an opportunity to drain. To stop this, you may install a drip system, which can be utilized to regulate greater or smaller streams of water straight to pots or flat grounds. You can set this kind of water with a timer and drip gauge.
Check each plant for its watering requirements. If the plant appears light then it requires watering and if the compost is dusty and dry it means that water is necessary. Remember that it is the roots that require access to water and not the leaves. Sprinkling the leaves is a misuse of water and may increase the scope of the disease.
Apart from these accessories above, many other accessories and supplies will make your work easier. Depending on your budget and commitment, you can add mist systems, fans, tool racks, potting benches, and shelving, along with many other accessories to make your job easier.
One of the greenhouse gardening basics to keep in mind while shopping for these accessories is to consider what your plants need, what you would like to have, and the amount of space your greenhouse provides.
For example, some plants require a slow steady supply of water from a drip irrigation System in order to maximize their growth while other can handle general watering techniques with no adverse effects on their growth.
Here are some basic greenhouse accessories that you may need:
- Shelvings are excellent space savers for small greenhouses. It is important for maintaining your greenhouse neat and organized. Pick the right shelving for your greenhouse here!
- Fans can serve various purposes inside an enclosed structure. Small fans help with bug and pest problems by drying up excess dampness or condensation. Larger fans can do everything and more. More particularly, they assist in purifying and even cooling your structure, especially when matched with the suitable ventilation systems. Find the perfect ventilation system here!
- A simple thermometer, like this one, may be a tiny accessory, yet it is unquestionably one of the most critical when it comes to greenhouse gardening. Some plants thrive best in particular temperatures, a thermometer will help to ensure the precise temperature is reached and if it falls under a safe limit.
- The demand to regulate the daylight getting into the glass is properly reached by the application of shading. It is particularly used to nourish plants that do not require a lot of light to grow. Check out our shade cloths here!
Pests control for greenhouse starters
A greenhouse setting favors the fast spread of pest populations. The friendly, humid environment and plentiful plants in a greenhouse give an attractive, steady habitat for pest growth. Immediate discovery and analysis of pests are required to execute the appropriate pest control decisions before the issue gets out of hand and you may experience financial loss. You can find all our organic pest control posts here!
These are the top pests to look out for:
Everyone knows aphids. These delicately colored, soft-bodied insects that fill the leaves of your beloved and precious greens. Take a peek at the bottom of the leaves, this is where aphids prefer to gather. Careful pruning and cleanliness are solid habits to stop aphids from damaging your precious plants.
Thrips vary in color from brownish to black. Thrips may leave damage extending from moderate to critical. You may stop these invasions by using screens on vents, examining new supply entering your greenhouse and regulating weeds will help to control thrips.
Bloodworms are elongated, roundworms comparable to fungus gnat larvae in lacking limbs and having a well-defined brown head. The red color is because of the appearance of hemoglobin, just like in human blood. The existence of hemoglobin lets them grow in water with extremely low oxygen content.
Slugs and Snails
Slugs and snails may increase when the moisture is high. These are nocturnal, fleshy, and slimy creatures. Cleanliness is necessary for slug and snail control. make sure your greenhouse is free of plant wastes like uprooted weeds, leaves, used boards, bricks or rocks that give a cooling and moistened hiding spots.
Common greenhouse gardening mistakes
The actual system of nurturing plants in a greenhouse needs a bit of confidence and ability. It may require a little practice beforehand so you won’t get caught up in one of these common greenhouse gardening mistakes. Here are some things to watch out for.
One of the significant mistakes inexperienced gardeners make is skipping to observe their greenhouse temperature on a regular basis. Use a basic thermometer, or buy a digital thermometer that also has the corresponding humidity, which is so crucial to identify for stopping heat loss.
Too much humidity may let mold, mildew, and bugs to run wild in your greenhouse. Too little will make your plants die of thirst. Misting is the best approach to improve humidity.
If your greenhouse has limited or no ventilation, your plants may die. You can utilize roof vents to release the warm air. Or sometimes a small fan may be required to keep sufficient air circulation.
Soil control is important, but it includes some additional challenges. Aside from the basics of combining compost and fertilizer occasionally, think of applying a blended soil mixture when preparing your bases. Do not apply old potting soil, which will carry pests and disease.
Roots from neighboring trees can invade your plants from underground, feeding up nutrients and moisture that is intended for your plants inside your greenhouse. It can also dump leaves or branches all year round. Shades can be a constant obstacle in restricting light as well. To care for your structure and plants, do not place your greenhouse near trees or position it accordingly.
The tips above will get you started on your blooming greenhouse gardening journey and ensure that your investment in a greenhouse is worth all the time, money and effort you put into your greenhouse. Having a greenhouse means any season is a planting season. Savor the excitement of having your homegrown fruits and veggies on your dining table. Have fun gardening all year round!
Want to start growing plants in a greenhouse? Did you just purchase one? Start with this beginner’s guide to greenhouse gardening to learn the basics!
A Beginner’s Guide to Using a Hobby Greenhouse
Are you thinking about adding a greenhouse to your garden? I fully support that idea! We have had our little greenhouse since 2016, and it has become a cherished part of our homestead! It enables us to start a significantly larger amount of our food from seed than we ever had space for indoors. It has also become a special and strangely intimate space to spend time “outside” on rainy winter days. Truthfully, we love and use it far more than we ever anticipated!
Benefits of using a greenhouse:
- Provides a protected place for seedlings and other tender plants.
- Extends the growing season.
- Allows you to grow tropical, rare, or other special plants.
- May allow you to garden year-round.
- Provides protection from many pests.
As you contemplate your options, let me share what we’ve learned and experienced in using and maintaining a hobby greenhouse. One may imagine it as a “plug-and-play” solution to extend their limited gardening season. While a greenhouse can create a controlled, protected, and sometimes more ideal climate than what is happening outside, it isn’t quite that simple. Without adequate controls or a watchful eye, a greenhouse can easily become too hot or cold for plants, overly humid, or even encourage pests and disease!
Read along to learn more about choosing and using a home garden or hobby greenhouse. This article will discuss hobby greenhouse styles, location, size considerations, foundation options, weather, climate control, and the importance of good airflow and ventilation.
Disclosure: This post contains some affiliate links to products for your convenience, such as to items on Amazon. Homestead and Chill gains a small commission from purchases made through those links, at no additional cost to you.
What is a Greenhouse?
A greenhouse, also referred to as a glasshouse, is a structure designed for growing and protecting tender or out-of-season plants against unfavorable conditions – such as frost or excessive heat.
“In the 17th century, greenhouses were ordinary brick or timber shelters with a normal proportion of window space and some means of heating. By the middle of the 19th century, the greenhouse had evolved from a mere refuge from a hostile climate into a highly controlled environment, adapted to the needs of particular plants. Large greenhouses are important in agriculture and horticulture and for botanical science, while smaller structures are commonly used by hobbyists, collectors, and home gardeners.”
A modern greenhouse is typically made of glass or plastic surrounding a minimalist frame – designed to maximize natural light. The sunlight that shines in performs several functions. It enables the plants to photosynthesize and grow. Additionally, the glass or plastic walls and roof trap the sunlight’s warmth and energy, keeping the greenhouse several degrees warmer than outside. This is especially important during cold winter weather and overnight.
When it comes to choosing a greenhouse, the options are seemingly endless! There are styles, shapes, and sizes to serve a wide variety of needs, spaces, and climates. For example, a table-top greenhouse may be the perfect choice for someone that only dabbles in gardening. A step up from that is a larger (but still portable) tented shelf greenhouse, enclosed with plastic – ideal for a gardener with a limited amount of growing space, or little need to keep plants protected.
Creative and handy gardeners may choose to make their own! A DIY greenhouse design can be as simple as securing sheets of specialized plastic over a frame of large hoops, or as intricate as puzzle-piecing together collected vintage windows into a cohesive little house. Trust me, I had allll the dreams of constructing a vintage glass window greenhouse at one time! Yet once I realized how expensive and hard-to-come-by those windows are in our area, I knew we needed a more straightforward, fool-proof option.
Enter: hobby greenhouse kits!
Hobby greenhouse kits are a great choice for a modest home garden, modern homestead, or even a mini-farm! Kits are available in many sizes and styles to meet your needs, designed for convenience and easy use. No matter your greenhouse of choice, kit or homemade, you will need to consider how to provide adequate airflow and temperature control. Also, how to secure it. Don’t worry, we’ll go over all of those things below!
I did a great deal of research before selecting our greenhouse: this Palram Mythos 6×8′ greenhouse kit. My only regret? I wish we would have gone bigger! Alas, we were working with limited space to put it.
When anyone asks for advice about greenhouses, one of the first things out of my mouth is: go bigger than you think you want! Space allowing, and within budget and reason of course. For example, if your contemplating between a 6×6’ and a 8×8’, go with the latter if you can! You will find ways to fill it and use the space, I promise!
To evaluate what size greenhouse will work best for you, consider the outdoor space where it is intended to live. If you are leaning towards a walk-in greenhouse, take into account the space you’ll want or need for your plants – and you! Will more than one person possibly be inside at a time?
Together, we sow seeds, pot up and thin seedlings, and do many other garden tasks inside our greenhouse. In a 6×8′ there is just enough room for both of us, the shelves, and our plants. Yet it can get a little cramped at times. We have limited elbow room! Last but not least, think about the space needed for storing other supplies, such as watering cans, pots, or seedling trays that you may want to keep inside.
Interior Design & Use of Space
What do you want to put or grow inside your greenhouse?
The addition of shelves or tables inside a greenhouse is ideal for raising seedlings, smaller potted plants, orchids, and other small or temporary residents. Inside our greenhouse, shelves or benches line three of the four inner walls. They are designed in a U-shape around the door opening and work space.
On the other hand, instead of shelving, many gardeners install raised garden beds and grow crops right inside their greenhouse! Or, straight in the ground below its roof! This option is particularly attractive for those with shorter growing seasons and unpredictable spring and fall frosts, making it more difficult to grow crops outdoors during those times. I have also seen some with a combination of both – with an area where plants grow in beds or large containers on the floor, and another section with shelves for seedlings.
Decide how you’d like to use the inside of your greenhouse before moving forward with setting a foundation or adding flooring material.
There are several factors to consider when deciding where to locate your greenhouse. For smaller, mobile units, you don’t need to commit to much. Yet for larger, more “permanent” structures, think about the following:
Choose a location for your greenhouse that receives full sun if possible. Or, partial sun if necessary. Plants like light, after all! It is easier to provide shade later if needed than it is to add more light if it is too dim. Also take into account how the sun exposure or shadows will change throughout various seasons, if you intend to use the greenhouse year-round.
The only spot we had available to conveniently install a greenhouse on our property is in our east side yard, tucked between the house and fence. Therefore, it only gets morning to midday sun, and is mostly shaded by mid-to-late afternoon. Because of this, we do have to use some supplemental lighting inside – especially during the winter when we’re starting seedlings. While not ideal for light, the location does provide a good amount of protection!
Wind & Weather
If your area is prone to high winds and powerful storms, heed some caution here. I have read a few horror stories about greenhouses being toppled or damaged in those events! However, I am not sure how securely those folks anchored their structures. Or, how conscientious they were about choosing a location.
Protect your greenhouse from strong winds by choosing a semi-sheltered location. For example, tucked near the side of a house, fence, or other structure, rather than in the middle of an open field. If you live in the Northern Hemisphere, locating a greenhouse along a south-facing wall or fence will maximize year round sun exposure while also providing some protection. From what I understand, freezing and snow is not usually an issue for quality hobby kit greenhouses.
Keeping in mind our greenhouse is semi-protected in its spot, it has proven to be very durable and strong! During a particularly unusual and intense storm, it withstood 40 to 50 mph wind gusts with no issues at all. She’s a champ.
Ease & Accessibility
Do you think you’ll want your greenhouse close to the house, making it easy to pop outside and check on your plant babes? Is there a water source and hose within reach, or will you be okay carrying in watering cans (like we do)? Do you think you’ll need or want a power source nearby? While I don’t condone this (and most electricians would likely advise against it), we do run an outdoor extension cord from a GFCI-protected outdoor outlet into our greenhouse. This is to power grow lights and fans we use on occasion. But we have solar fans too! We’ll talk about them soon.
Finally, as you choose a location for your greenhouse, think about the ground surface. Is it level? Do you want to plant things in the ground below it?
Making a Greenhouse Foundation
Your greenhouse should be installed on a sturdy, level foundation. Therefore, seek out a location that is already level – or one that can easily be modified to create a level space! The foundation will provide a base to anchor the greenhouse to. Also, a nice level and continuous base will help “seal” the space around the bottom, reducing unwanted air exchange or entry by vermin and pests. It is not a great idea to set your greenhouse directly on the ground for these reasons.
There are many options for foundations. Some of the more popular foundation materials include wood, concrete blocks or pavers, concrete slabs, or even on concrete walls. Wood is likely the most inexpensive and easy to work with. If you choose to make a wood foundation, I suggest using a naturally durable and rot-resistant wood like cedar or redwood. An existing concrete patio could make a great level foundation! However, keep in mind that water may not have anywhere to drain to.
We built a concrete block wall foundation for our greenhouse. I liked the look, durability, and also that we could build it up high. By installing it on top of the block wall, we gained over a foot of height and headroom inside! See this step-by-step tutorial on how we built our concrete block greenhouse foundation.
Securing Your Greenhouse
No matter the type of foundation you choose, factor in how you will secure the greenhouse to it. This is essential! If not properly secured, it can easily get overturned in the wind. For example, our greenhouse is anchored to its foundation with concrete screws all around the bottom of its frame. All hobby greenhouse kits should have holes or other attachments made to secure it down. Staking it into the ground will likely not be sturdy enough during a weather event – unless perhaps if very long and secure stakes are driven deep into firm soil.
For more ideas and details about greenhouse foundations, check out this article by Little Green House.
Once you have your foundation figured out, it is time to select a floor material for inside the greenhouse. An ideal greenhouse flooring material will provide excellent drainage, and also prevent weeds from growing. Greenhouses create an ideal climate for plants to grow, including ones you don’t want growing there! Small rock material such as pea gravel is a popular choice inside greenhouses.
The floor of our greenhouse is covered with several inches of pea gravel. Because pea gravel tends to sink and move when you walk on it, we also added a few stepping stones in the middle as a path. Before putting the pea gravel down, we lined the space under and around the greenhouse with weed block landscape fabric over the native soil. Rather than landscape fabric, you could put down several layers of cardboard below a rock floor instead – though it will not be as effective at preventing weeds long-term.
We use this commercial-duty weed block fabric by Landmaster, both in the greenhouse and in our garden where needed, such as under our raised beds. It is significantly more thick, durable, and effective than many other common thin, black, plastic-like weed barriers available. It doesn’t easily rip or make such a mess either.
The most practical greenhouse shelves are slotted, allowing free water drainage from plants and containers. Many greenhouse kits that I’ve seen do not come with shelves, but you can buy them separately or repurpose other shelving units or tables you already have. Conversely, you could build you own!
We built our custom wood shelves/tables to fit perfectly inside our greenhouse. Since wood inside a greenhouse will be exposed to moisture, choose a type of wood that is durable and naturally rot-resistant. Our benches are heart redwood. Cedar is also an excellent wood choice! I will share a tutorial about how we built our redwood shelves soon.
Metal shelving units (rust-resistant) are another popular option for greenhouse shelves, or wire over wood table frames. Wire fencing over a frame will need support in the middle, to hold heavy plants and prevent sagging. These types of “metro-racks” have the added benefit of being adjustable or stackable, making it easy to rearrange your shelving depending on the season or types of plants inside. Keep in mind that shelves with many levels will cast shade on those below.
Okay guys. Now that we’ve covered basic greenhouse infrastructure and design, it is time to dive into some very important details: about actually using the greenhouse!
Having a greenhouse is a great way to create an ideal, controlled environment for your plants… but controlled is the operative word. Contrary to what some folks may think, a greenhouse doesn’t provide that ideal environment completely on its own by simply existing. Sure, its enclosed glass or plastic walls help, but you need to add some controls of your own. Otherwise it can easily become too hot, cold, or stuffy inside!
For most situations, the goal is to keep the temperature inside the greenhouse as steady as possible. Thankfully, there are some pretty sweet and sophisticated tools available to help automate the control process! Or, you can manually manipulate the environment. We’ll talk about a little bit of both below.
In order to assess the internal conditions of your greenhouse, it is extremely helpful to have a thermometer inside. We love this thermometer. A wireless sensor portion stays inside the greenhouse, while the rest of the unit is inside the house. This makes it super easy to keep an eye on things remotely! You can also add additional sensors to monitor multiple zones, such as the greenhouse versus outside.
Keeping a Greenhouse Cool
When the hot sun beats down on your greenhouse, it can easily become too hot for the plants inside – and even kill them. This is particularly true during the summer time, unexpected heat waves, or if you are growing tender, heat-sensitive plants.
Ways to keep your greenhouse cool:
- Propopen the greenhouse door on hot days. But be sure to close it up again before the sun goes down, to trap a little warmth for the night time!
- Open the roof vent to allow hot air to escape, since heat naturally rises. All quality greenhouse kits should have at least one roof vent, or several for larger greenhouses. Some also have side vents or louvered windows. To automate this process, we installed an thermal sensing vent arm. It automatically opens the roof vent half way when the temperature reaches about 80F, wide open at 90F, and closes again when it cools down. We don’t even have to think about it!
- Use fans to promote good air circulation. Greenhouse ventilation is so important that it deserves a section of its own, expanded on below.
- Hang shade cloth, either inside the greenhouse or over it. Shade cloth comes in a variety of “strengths” or grades. For example, one that blocks 30% of UV rays, or others that block 50% UV. We have a section of shade cloth always available in the sunniest section of our greenhouse. Clips hold it in place, and it easily rolls up out of the way when not in use.
- Wet the inside of the greenhouse surfaces, such as the gravel floor, paths, inner foundation, and even benches or shelves with water. This is known as “damping down”. As the added moisture evaporates in the heat, it raises humidity and naturally cools the air inside the greenhouse.
- Choose a wise orientation for your greenhouse from the start. Meaning, if you intend to use your greenhouse during the summer but also know your area regularly experiences extreme heat at that time of year, consider a location with partial afternoon shade.
A greenhouse’s glass or plastic walls and roof are excellent at trapping heat inside while the sun is shining, but they are not good at providing insulation. For that reason, greenhouses can rapidly lose heat at night, especially during the winter. Depending on the greenhouse, it will keep the temperature inside a couple of degrees warmer than it is outside at night, but not much more than that. Without intervention or smart design, that is!
Of course, you don’t have to heat a greenhouse. It all depends on your climate, and what you hope to grow or store inside the greenhouse at various times of year! To provide additional warmth within a greenhouse at night, you can rely on supplemental heat, or natural insulation and thermal mass, or even a combination of both.
Ways to heat a greenhouse:
- Use Thermal Mass: Glass and plastic aren’t great at retaining heat, but some other materials are! Large volumes of water or big solid objects such as concrete blocks are excellent at absorbing and retaining heat – staying warm for many hours after the sun has passed. To take advantage of thermal mass heating, many gardeners store large drums or tanks of water inside their greenhouse as a means of frost protection. The drums are often black in color, and stored in a location in the greenhouse that receives a lot of direct sunlight. They absorb heat and energy during the day and then re-radiate that heat back out to the surrounding air at night as the temperatures drop. Frost is rare where we live, but our stone foundation serves as some thermal mass!
- Insulation: The location of your greenhouse may provide some natural insulation, such as near a fence or house. A wall may also re-radiate some heat back towards the greenhouse in the evening. Additional insulation can be provided around the outside of a greenhouse, lining the inside of the walls, or directly over the plants themselves – including frost blankets, specialized greenhouse insulation material, or even bubble wrap! Also, a greenhouse full of plants will retain more heat overnight than a virtually empty one.
- Heating devices: With an available power source, space heaters can be used to keep a greenhouse warm. Practice caution and good common sense here! We have used a space heater in our greenhouse in a pinch a few times, but it does make me a little uneasy. On the other hand, a good friend of mine runs a space heater in his orchid greenhouse overnight almost year-round! We also use heat mats under trays of seedlings to keep the soil warm at night as needed. Seedling heat mats raise the temperature of our small greenhouse by a few degrees. However, they likely wouldn’t be enough to warm the air and save the plants in a true freezing event.
- Make a Heat Sink: This option is similar to the water barrel idea, but underground! To create a heat sink, dig out a large area below the greenhouse, line it with insulation, and fill the space with materials with high thermal mass (e.g. bricks). The heat sink captures and stores daytime heat, with the assistance of a fan and piping system to help the movement of warm air. It then radiates back out at night. To learn more about creating a heat sink for your greenhouse, check out this video by Mitch Varn, or the BBC video linked below the photo.
Greenhouse Air Circulation & Ventilation
We’ve reached one of the last but possibly most important components of this guide! Air flow. To keep plants happy, pests at bay, and temperatures steady, a greenhouse needs good air circulation and ventilation.
Vents in the roof or wall of a greenhouse usually do a good job at passively allowing hot air to escape. When you pair that with opening the main door, it creates a nice cross-breeze that will draw fresh air through the greenhouse. You can also use fans to create additional air flow, such as an exhaust fan.
Our Automated Greenhouse Ventilation
When we first set up our hobby greenhouse, I wanted to make the ventilation system as automated as possible. With our busy schedules, the last thing I wanted to worry about was accidentally frying plants because one of us forgot to open or close the vent and door!
As I mentioned before, we utilize an automatic vent arm to control the roof vent for us. Additionally, we installed two solar-powered fans inside. The fans are designed to vent attic spaces, but work perfectly for our greenhouse! One of the fans is hooked up in the corner pointing inward, providing general air circulation around the space inside. The other is installed in the wall of the greenhouse pointing outside. It exhausts air out while creating a pull of new air in through the roof vent.
To install the exhaust fan, we cut a hole in the greenhouse wall with a sharp utility knife. We also installed a little awning on the outside to protect it from rain. When we have rare frost warnings, we cover the fan and opening with bubble wrap to prevent cold air from getting in. Both solar panels are mounted on top of the chicken run that is directly behind the greenhouse.
When the sun comes out, the fans kick on, the automatic arm swings the roof vent open, and the greenhouse is kept perfectly temperate most days! Depending on what is growing inside, we still open the door or even roll out the shade cloth on hotter-than-usual days.
With a clever design, you may not need any bells and whistles for your greenhouse! Yet depending on the situation, there may be times you want extra gadgets – such as grow lights, shelves, clips for hanging things, and so on. For example, the Palram greenhouse series has add-on shelves that attach directly to the walls. They also make specialized clips/hooks that attach to the frame of the greenhouse. We use those for hanging shade cloth, fans, lights, and more! We also have this solar light bulb hanging from the roof to provide light when we’re working inside in the evening.
And that completes your crash course in using a hobby greenhouse 101.
I know, that was a lot of information to digest at once. But as a newbie or future greenhouse gardener, I hope you found this article to be helpful! Please feel free to ask questions in the comments.
If you plan to use your greenhouse for starting seeds, be sure to check out our Seed Starting 101 article. I also plan to write follow-up articles on pest and disease control inside a greenhouse, along with cleaning or sanitizing tips. In all, we have found our greenhouse to be a very worthwhile and enjoyable investment. Enjoy your new toy!
Read along to learn about using a hobby greenhouse – including tips on style, location, size, foundation, climate control, and ventilation!