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.”Encyclopedia Britannia
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:
- Prop open 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!