If you’re like me and live in an area that gets cold winters (the midwest for me), then you might be interested in setting up a greenhouse. Having a greenhouse greatly increases the amount of plants you can grow and for how long you can do so. Done right, you can have a thriving garden all winter long.
In this article, we’ll look at everything a beginner needs to know about starting a greenhouse. We’ll start with the benefits and how a greenhouse works, and then we’ll jump into setting up your own greenhouse and all the things that go into that.
Benefits of Greenhouses
Before we get into the specifics of setting up a greenhouse let’s talk for a minute about why you might want to set up a greenhouse in the first place. Greenhouses provide us gardeners with a lot of benefits, and depending on your goals may or may not be a good fit for your garden.
First off, a greenhouse provides a sound structure and protection for your plants. This helps shield them from inclement weather that might otherwise damage your plants. This is especially true for seedlings or young plants that can be damaged by high winds or heavy rain.
It also provides some level of protection from pests. While it’s not perfect, it does greatly reduce the chances of bugs causing problems with your plants. The greenhouse makes it more difficult for them to get to your plants than if they were more exposed. It doesn’t however completely remove the risk, so you should still be diligent about checking your plants for signs of infestation.
What it will generally provide near perfect protection from is larger animals like birds, squirrels, or deer. These critters often are problematic for gardeners and can ruin a good harvest. A properly secured greenhouse should prevent any of these types of animals from harming your plants. If you find your plants frequently visited by larger critters, a greenhouse might be the perfect solution to protect your plants.
Extends The Growing Season
Even with minimal effort, a greenhouse allows you to drastically increase your growing season. With a greenhouse, you can start earlier and plant later than you could normally. This is a big benefit for most growers, and can allow you to harvest more and harvest earlier.
With a little effort you can even push this further. A greenhouse gives you a nice base to work from, and there are multiple things you can do to improve its usefulness and further extend your growing season. We’ll look at some of them a bit later in this article.
Allows Winter Gardening
Depending on your climate, a greenhouse can often allow winter gardening. The more mild your winters are the easier it will be to do so.
Even those with harsh winters can often garden for some or all of the winter. It often requires some effort to maintain enough heat, but it’s not that difficult once you get it down. Using some of the techniques detailed below, you can grow a garden in your greenhouse all winter long.
Easier Environment Control
Another big perk that greenhouses give over outdoor planting is a much finer control over the environment. While not as easy as completely indoors, a greenhouse lets you better control things like temperature, humidity, and of course water.
There are many tricks for tweaking these values as well. A savvy gardener can adjust the temperature in their greenhouse for example, and keep it from getting too hot in the summer. We’ll look at how they might do later on in this article.
Faster Plant Growth
In many cases, you’ll find that your plants will grow faster and larger in a greenhouse than elsewhere. This is because a greenhouse is specifically suited to plant growth. This also makes it a great option for starting seeds and seedlings and giving them a good environment to start their growth.
Can Grow Exotic and Non-native plants
Lastly, due to increased control over the environment, greenhouses allow a versatility in plant choice. In many cases, you’ll be able to grow exotic or non-native species that require a far different climate than the one you live in. Many gardeners are able to grow tropical plants in their greenhouses, even in places that are not conducive to such plants like the midwest.
How Do Greenhouses Work?
It’s also important for us to take a moment to look at how greenhouses work. This will help us later in determining an ideal location for our greenhouse.
In general, greenhouses work by trapping in the sun’s light which provides both warmth for your plants and energy for them to photosynthesize. Greenhouses are constructed in a way to maximize how much sunlight your plants are able to receive.
Most greenhouses are built either out of glass or plastic for this reason. These materials allow lots of sunlight through and make up the bulk of the construction to maximize its effect. Most greenhouses use minimal framing to maximize light intake.
While this abundance of sunlight can be a good thing, it can also cause issues. Greenhouses are typically far warmer than the outdoors since they’re taking in and containing as much as they can. This is great in the winter or during cool nights, but can be a negative during the peak of summer. Keep that in mind as you plan your greenhouse.
Building a Starter Greenhouse
The great news about starting a greenhouse is that there are dozens of ways to get started. While many people think of greenhouses as large, immovable structures, that doesn’t have to be the case. There are many different greenhouses on the market that are much smaller and manageable, and you always have the option to build your own.
Here’s a few examples of some pre-built greenhouse options:
Small Frame Greenhouse: This is a smaller sized greenhouse that can fit on a deck or in a sunny location in your yard. It’s ideal for smaller grows, and doesn’t take up much space.
Mini Tiered Greenhouse: This is another small treehouse that smartly utilizes vertical space. It’s a great option for getting started and for those with minimal space.
Walk-in Greenhouse: Here’s an example of a more classic style greenhouse that has enough room to walk in. This is great for those looking for more space and want to grow more plants. Bear in mind that this greenhouse is going to be more permanent and harder to move than smaller options.
You also always have the option to build one yourself. There are lots of great green house plans available for those that want that route, and you always have the option to improvise as well. Many people have used reclaimed glass or even sheets of plastic to create a makeshift greenhouse. These can not only be perfectly functional, but also stylish and affordable.
One thing to keep in mind is that the smaller greenhouses are going to have a harder time maintaining heat in the winter. Many of the heat improving techniques we’ll see rely on a larger space to work correctly. That shouldn’t dissuade you from building a small greenhouse if that suits you, but think about how you’ll heat it in the winter if you want a year round garden.
Hopefully by now you’ve started to get ideas for the perfect greenhouse. Before you get too far into planning though it’s important to keep in mind a few key points. In this section we’ll look at all the considerations so you can make the most informed decision on your greenhouse journey.
Position and Size
The first thing to determine is where your greenhouse is going and how big it’s going to be. In most cases, your location is going to dictate the size of your greenhouse. You want to make sure that you put your greenhouse in an area that gets lots of sunlight to maximize its benefit.
The great news is, as shown above, there are sizes of greenhouse for almost any location that you can think of. Even a small space on a deck, for example, is enough to start a small greenhouse.
While a bright, sunny location is best, you should always be wary of how much light your greenhouse is going to get. This is especially true in areas that experience very hot summers. Think about how hot your summers get, your greenhouse is likely to be a few degrees warmer than that.
Depending on your plants that might actually be too hot. There are some ways to reduce heat as we’ll explore below, but any easy one is to simply position your greenhouse to get some shade. Getting a bit of afternoon shade can drastically cool your greenhouse, and might be smart if you’re growing plants that can handle the temperature. Bear in mind that shade will carry over into the winter too, and that might mean you have the opposite problem as the temperatures drop.
Lastly, it’s also important to consider any extreme weather you might experience when planning your greenhouse’s location. There’s horror stories of powerful storms toppling greenhouses and destroying them.
While a good foundation and securing the greenhouse goes a long way here, you can also position to minimize a storm’s impact. Placing it in an area that gets partial cover, like next to your house or garage, can limit a storm’s impact. Keep this in mind if you live in an area prone to extreme weather. As we’ll explore later, these lean-to style greenhouses can also have some added benefits outside of protection from the elements.
Foundation and Stability
If you’re going with a larger greenhouse you’ll want to consider how you’re going to give it enough stability to stand up to storms. An improperly secured greenhouse is just asking to be blown over in your next storm or gust of wind.
Luckily, most kits and plans will come with holes or attachments to help secure your greenhouse. In many cases these will be screws that you drill into some type of foundation.
Speaking of foundation, it’s a good idea to build a simple one for your greenhouse. This provides added stability, but also provides a seal that can keep out pests and rodents like mice. Most gardeners will build theirs out of wood or concrete, either of which can provide a solid foundation for your greenhouse. Like any good foundation, you’ll want to either start on a flat surface, or do some work to level the area yourself.
While not strictly necessary, consider how you’ll layout the interior of your greenhouse. Many people will install shelves in their greenhouse while others will grow out of containers and planters.
You’re really not limited here, so don’t feel like one way is better than another. It really depends on what types of plants you’re growing.
This also gives you a lot of creative freedom to really make the greenhouse yours. Even a small greenhouse gives you opportunities to leave your mark on it. For some ideas, check out these inspiring greenhouses.
Heat is a big component of greenhouse growing, and can be both a blessing and a curse. While some heat is desirable, too much can damage your plants. Part of successful greenhouse management is controlling that heat. We’ll break down this into two sections, decreasing the heat and increasing it. Both are necessary, and have their own tricks to do right.
In either case, the goal of a greenhouse is to try and get a relatively even temperature throughout the day. You want to avoid large swings, changes should generally be gradual like it is in nature. If you’re growing in a greenhouse then you should definitely get a good thermometer, it’s an essential tool for a successful greenhouse.
Oftentimes in the summer you’ll want to reduce the heat in your greenhouse. In many cases, it’s best to be proactive here and act before the temperature reaches too high. This both prevents exposing your plants to too much heat, but it’s also usually easier if you act before it becomes too warm.
Here are some easy ways to reduce the heat in your greenhouse.
Start With Location In Mind
As mentioned above, location plays a big role in how hot your greenhouse is going to get. The more sun it gets per day the more it will warm up, so starting in a shadier location can reduce the temperatures your greenhouse reaches.
That said, the point of a greenhouse is to get a lot of sun so you don’t want to go too shady. If you’re concerned about the heat, choose a location that gets a little afternoon shade. This is a good mix of bright days with a chance to cool.
For more temperate climates you should reduce the amount of time your greenhouse is in the shade. Depending on your maximum summer temperature, you likely won’t need any shade at all. The rest of these tips deal with active heat mitigation, so even if you do place it in full sun you have options.
Open Roof Vents
Most if not all large greenhouses are going to come with roof vents for the exact purpose of venting excess heat. Hot air rises, so roof vents are perfectly placed to move heat out of your greenhouse.
Some larger greenhouses also come with side vents or openable windows. These all serve the same purpose of giving heat an easy route to escape.
Open The Door
Similar to vents, you can simply prop open the door of your greenhouse to get rid of some excess heat. This can be paired with open vents and using a fan to help reduce heat in a hurry.
Use a Fan
Good ventilation is important, and we’ll talk about it more below. That said, it’s also a good way to reduce the heat. A fan can help cycle air faster, so it’s good to pair it with an open door or vent.
Water The Ground
Another popular tip is to water the ground of your greenhouse. This is called damping down. This works because as the water evaporates from the ground it raises the humidity level in your greenhouse and reduces the temperature.
This is smart to do often as the added humidity is good for your plants. Good levels of humidity can help protect your plants if it does get too warm in your greenhouse; humidity does wonders to help prevent heat stress. It also helps prevent certain kinds of bugs, so it’s a win in multiple ways.
Shade cloths are special made fabrics that are built to block out a certain portion of the sun’s UV rays. This amount can vary, common types block 30% or 50%. These are great options for reducing the heat in your greenhouse but will also block beneficial light as well so use these sparingly.
Don’t Go Overboard
While reducing the heat it’s important to not go overboard. As we’ll see below, greenhouses often have trouble keeping heat once the sun goes down. This means you want to ensure that your greenhouse maintains enough warmth to last through the night. Reducing the heat too much can damage your plants when the temperature drops after the sun goes down.
On the flip side, sometimes you want to increase the heat in your greenhouse. This is usually the case during the winter when the temperature drops significantly. While greenhouses are great at absorbing heat, they are often poorly insulated and lose heat quickly.
This can be very problematic in the cooler months when getting heat is difficult in the first place. Luckily, there are several options to increase the heat in your greenhouse.
Start With Position, Again
Like with decreasing heat, your position can also play a role in increasing it. The sunnier a spot you choose the more warmth your greenhouse will naturally get.
Location can also play a role in insulating your greenhouse or providing it with radiant heat. A common greenhouse design that utilizes this is the lean-to. In this setup, the greenhouse is usually placed with one wall being that of the other structure such as a house or garage.
This wall provides some insulating properties, but can also radiate heat depending on what’s on the other side. This can end up providing an active heat source for your greenhouse without any extra effort on your part. If you know you want to garden in winter, and you get harsh winters, consider a lean-to design to maximize this effect.
Add Thermal Mass
Another tip is to add items with a higher thermal mass to your greenhouse. Thermal mass is the ability for a material to absorb and radiate heat. The typical building materials of a greenhouse, plastic and glass, have a poor thermal mass and therefore don’t give off much heat while also losing what little heat they have very quickly.
What you want to do is to add items that have a high thermal mass. One of the easiest items to use is water. Using large containers of water provides lots of high thermal mass material to your greenhouse, and does so relatively inexpensively.
Place the water in the large containers and leave it in a sunny spot in your greenhouse. During the day, the sunlight will heat the water up. Then, during the night they will radiate back out that heat and help increase the overall temperature of your greenhouse. The more water you use the larger of an effect it will be.
A few other less commonly used alternatives include:
- Dense concrete block
Use a Heater
If all else fails, you always have the option to use a heater. This is often just a short term fix, and can be combined with added thermal mass to keep the heat around for longer.
Be careful not to place the heater too close to your plants as the extra heat can damage them. Also, follow any safety precautions and check the heater often. The last thing you want is to start a fire in your greenhouse.
Another important thing to keep in mind is the air circulation in your greenhouse. Proper airflow is important for your plants and has the following benefits
- Promotes healthy plant growth
- Helps regulate temperature
- Helps prevent certain pests
Improper airflow is a big reason lots of gardeners have trouble when first starting their greenhouse.
That in mind, getting proper air flow is not difficult at all. A gentle breeze through your greenhouse is usually enough, it doesn’t need to feel like the middle of a hurricane.
Opening up the roof vents and propping open the door is usually enough to facilitate this. Together, these will create a nice cross breeze and help cycle new air into your greenhouse. For a little more, add a small fan that will further increase air flow.
Flooring & Drainage
If you have a large enough greenhouse then you will likely also have to figure out some type of flooring. Most plans and building kits only provide the framing, and leave the floor up to you.
A greenhouse floor is going to have two main purposes, providing drainage for excess water and preventing weed growth. There are a lot of options here, but we’ll offer our recommendation which is popular among many greenhouse growers.
To start, lay down a layer of weed tarp in the area your greenhouse will be built. This provides a thick layer of protection that will prevent weeds from springing up in your greenhouse. Don’t neglect this step as it’s far easier to prevent the weeds than it is to deal with them once they start popping up.
For the actual flooring, many people will use rocks or small pebbles as their primary flooring material. This gives you a solid floor that also allows excess dirt and water to drain. Greenhouses can often get messy, so having a floor that’s okay to spill on is essential. This also gives you the ability to water the floor and take advantage of “damping down” as mentioned above.
Popular Greenhouse Uses
At this point, we’ve covered a lot of the basics of setting up and running a greenhouse. In this section, I wanted to look at some more specific use cases of why people build a greenhouse in the first place.
Each of the below sections gives specific tips for how to utilize your greenhouse for a particular use. Keep in mind that many people will use their greenhouse for multiple purposes, so don’t feel like you only have to pick one of the below.
Starting Seeds in a Greenhouse
Many people use their greenhouse as the perfect home to start their seeds. Greenhouses are naturally quite amicable to seed growth due to its high temperature and high humidity. This makes it the perfect environment for starting seeds and seedlings.
Most gardeners will start with seed trays, and start a fair number of seeds at one time. This gives you a better chance of having a successful plant as it’s rare for all seeds to sprout.
Outside of that, the major concern you’ll have is temperature; you don’t want it to drop too low. This is often the case for gardeners starting their seeds a bit early when the temperatures are still low at night. Take care to prevent the temperature dropping too low as many seeds won’t germinate unless their soil is warm. Then, follow normal seeding planting tips.
Starting Early in The Season Or Going Late
Many gardeners also use their greenhouse to start earlier in the spring and go later in the fall than nature would normally allow. This often allows them to harvest more in a single growing season.
This is generally the plan for those that live in areas that experience harsh winters and don’t want to deal with keeping their greenhouse warm all winter long. It’s usually easy enough to do so in spring/fall, and this increased growing season is enough to make the greenhouse worth it, even without much use in the winter.
Many gardeners will also look to move some of their plants out of the greenhouse once summer is in full swing. Depending on your timing, this can reduce issues with high-heat or even get rid of them entirely. The heat in the greenhouse won’t matter if there’s no plants inside of it.
Keep in mind that you may have similar issues transitioning from a greenhouse to outdoors as you would moving any indoor plant outdoors.
Growing Through Winter
Probably the classic image most people have of the greenhouse is a nice warm home for your plants surrounded by the snowy winter landscape. While winter growing is entirely possible, it can be difficult if you live in an area that experiences cold, harsh winters.
The biggest issue here is going to be heat. In the winter it can be difficult to get enough heat to keep your plants warm. While many plants go dormant in the winter and can survive at lower temperatures than normal, a hard frost in the winter is going to be too cold for most.
Depending on how low the temperature gets, adding some thermal mass to your greenhouse is the easiest option. This will help, but won’t be enough to offset very cold temperatures. In those cases, you might want to combine this with a heater to help get the temperature up in the first place. This is going to be especially problematic at night when you lose any warmth the sun provides.
Speaking of the sun, you may also have issues with lack of sunlight in the winter. This is going to be especially true if you’re growing exotic or tropical plants that need full sun year round. In these cases, you probably will need to create some type of grow light setup to provide the extra light. Depending on your setup and types of lights, this can also provide a little extra heat. Just be careful not to burn your plants and not to start a fire in your greenhouse.
One tip for winter growers is to grow plants that are naturally more resilient to cold temperatures and frost. Certain leafy greens, like kale, are very cold tolerant and grow well in temperatures that would kill most other plants. Starting with plants that can grow in cooler weather reduces the effort to keep your greenhouse warm.
While that covers the basics, many people continue to expand their greenhouse by adding their own additions. These are often in response to a problem they’re facing, such as getting too warm in the summer, and help them better manage their plants.
This step is completely optional, and up to the individual gardener on what they want to do. We won’t get into too much detail here, each of these could take up its own article, but instead will give you just a brief overview. Some popular additions are:
- Setting up grow lights and timers
- Adding automatic or remote controlled vents
- Adding lights for visibility at night
- Built in fans and heating
- Self watering and irrigation systems
The options are endless, and your imagination is the only limit. If you want to improve your greenhouse, start thinking about the problems you face and look for ways to fix them.
Beginners Greenhouse Guide
With that, we’ve reached the end of our introduction to greenhouses. There’s a lot more that could be said, but this should give you a nice primer to build your knowledge from.
At the end of the day, greenhouses are an excellent tool to help extend your growing season and give your plants a safe place to live. A well placed greenhouse can drastically increase your harvest yields, or provide an ideal location for plants that might otherwise not grow in your area. With some care, you can grow plants year round, even in the dead of winter.
Do you have a greenhouse? We’d love to hear about how you built it, what you grow in it, and any challenges you faced. Reach out to us, and let us know!
Beginners Greenhouse FAQ
How Big Of A Greenhouse Should I Get?
This is largely dictated by your space and what you want to grow. The first thing is always to find an acceptable location that gets lots of sunlight and use that to judge your greenhouse’s maximum size. From there, think about what you want to grow and how much of it, and use that as a guide for your greenhouse’s size. Most gardeners will advise you to go a bit bigger than you think as once you start growing in your greenhouse you’ll wish it was bigger.
Can I Grow Plants in a Greenhouse in the Winter?
Yes you can, but how easy that will be depends on your local climate. The colder it gets in the winter the more difficult it will be. In any case, keeping the greenhouse warm will be your biggest challenge and key to a successful winter growth. To make things easier, look to grow cool weather in plants in the winter to reduce the need to keep it heated.
How Can I Increase the Temperature In My Greenhouse?
Outside of using a heater, adding thermal mass to your greenhouse is usually the go to method. This involves adding large amounts of material, usually water, that holds heat well. As the temperature cools, this material will be warmer than its surroundings and begin to slowly radiate heat. This has the effect of keeping the immediate area much warmer than the temperature would normally allow.
Can a Greenhouse Get Too Hot For Plants?
Yes it certainly can, especially for ones that aren’t tropical. Anything above 90°F is generally too warm for most plants and can actually harm them. Above in this guide, you’ll find some tips for reducing your greenhouse’s temperature.
Do Plants Grow Better in a Greenhouse?
Yes, many gardeners report better growth in greenhouses. This is largely due to a greenhouse providing ideal conditions for plants to thrive in.
Do I need a Fan In My Greenhouse?
While not necessary, it can help with airflow. If you have enough ventilation then a fan might not be needed. If you find that airflow could use a bit of help then a fan is an easy way to do that.
What Can You Grow in a Greenhouse?
Almost any plant is able to grow in a greenhouse, provided you have enough space for it.