Congratulations on your decision to buy a greenhouse! You’re about to embark on a journey that can make gardening more enjoyable for the entire year. But as it with any new projects, it’s essential to begin with research. It’s the best way to avoid hassles down the road that could affect the health of your plants.
That's why we wrote the Ultimate Greenhouse Buyer’s Guide.
Table of Contents
- 1 Benefits of Having a Greenhouse
- 2 The Downside of a Greenhouse
- 3 Top Considerations
- 4 Types of Greenhouses
- 5 Design and Materials
- 5.1 Types of Frames
- 5.2 Frame Material
- 5.3 Common options include:
- 5.4 Important Aspect When Choosing a Greenhouse
- 5.5 Glazing
- 5.6 Common materials include:
- 6 Insulation
- 7 Ventilation
- 8 Heating
- 9 Tips for Having a Greenhouse
Benefits of Having a Greenhouse
Perhaps the greatest advantage of a greenhouse is that it lets you extend the growing season. You can start plants early and get them cold-hardened by placing them outside. That will free up space in your home where you’d have them set up inside for the same purpose. You also can keep plants going longer into the fall.
But the benefits don’t end there. There is no such thing as a 100 percent guarantee that deer or other pests won’t find your crop of fresh vegetables and flowers. A hungry deer is a desperate one. Even those daffodils might start to look good after a while. With a greenhouse, you can eliminate that problem and keep them safe. It’s essential to look at the whole picture.
The Downside of a Greenhouse
There are also some other important considerations to take into account. A greenhouse is an investment whether it’s a DIY project of a pre-fab kit. And it certainly is not a maintenance-free venture. You can think of a greenhouse like a large potted plant. It’ll get drier and hotter quicker in an enclosed area. That will mean extra work on your part to ensure an optimal environment.
While you may think a smaller one would mean less work, the opposite is true. The temperature within a smaller space will fluctuate more readily. During a hot summer day, that can mean the difference between cooking your plants on a sultry afternoon or keeping them happy. A larger greenhouse is the better option. You have to think about the impact that greater real estate will have in your yard.
There are a few other things you need to consider before setting up your greenhouse. A few are deal breakers, so it makes sense to look at them up front. They include:
- Local laws and regulations
You’ll save yourself a lot of time and frustration if you do your homework first.
Local Laws and Regulations
Some cities and counties may have laws in place that you’ll need to research. You may find that you need to secure a building permit, depending on the size and type. Make sure and learn the details. It may vary if the structure is enclosed on all four sides or not. There may be regulations that dictate how close you can have it to your house.
Don’t forget to check with your homeowners’ association too. Many have specific guidelines about what you can build or do with your lot even if you own the property. It’s best to play it safe before you start off with your new greenhouse. Know exactly what is permitted and what is not when it comes to size, attachment to an existing structure, and placement.
Keep in mind the size of the greenhouse when considering where you’re going to put it. For a freestanding structure, you’re looking at recommended something about 8 feet wide by 12 feet long to strike that balance for temperature control. You can get by with something smaller in the 6-foot range for a lean-to greenhouse, assuming no regulations prevent it.
Also, consider the exposure when thinking about a location. That will influence your choice of plants and how you’ll use your greenhouse. Ideally, a southern or southeast one is best to take full advantage of the sunlight. A northern exposure, on the other hand, offers the least amount of light. Only plants that thrive in shady conditions may do well in these spots.
Placing your greenhouse near trees or shrubs is a smart move. While the sunlight is welcome, the plants may have a hard time with the hot afternoon sun. Also, let it do double-duty by placing an attached one on the side of your house when it can block drafts in your home.
The old adage of you get what you pay for applies to greenhouses too. They’ll vary in the materials, ease of assembly, and durability. The stability of the structure is an important consideration, especially with a freestanding one. It’ll have to handle the strong winds of those summer storms.
You should consider the entire picture when it comes to cutting corners to save money. Some materials may provide some immediate savings. However, their value diminishes if you have to replace them because they don’t last as long.
Think about the day-to-day use of your greenhouse in the decision-making process. Consider its placement so that you have ready access to water and power, if required. Also, you’ll need to plan for drainage around it even if that just means digging a trench around it. Water that pools around it can create the perfect setting for bacteria and mold.
Types of Greenhouses
The first consideration with the types of greenhouses is whether it is attached to an existing building or freestanding. The advantage with the former is that it adds to the overall stability of the structure. You can optimize its placement to lend some benefits to your house too. With the latter, there are additional features you’ll need to think about in addition to its ability to withstand the elements.
Then, there is the overall form. You’ll find many options for greenhouse shapes to fit whatever space you have to fill. Keep that in mind when reviewing your options.
Your greenhouse can also serve as a focal point in your yard.
The main types of greenhouses include:
- Attached lean-to
- Attached even-span
Each one has their own pros and cons. Some work better in certain situations better than others. Make sure you measure that space you are allotting for your greenhouse including the clearance above the spot.
Attached Lean-To Greenhouse
This type has several pros and cons. On the positive side, it’s a good choice if you have a limited amount of space in your yard. You can tuck it into a place that may not get a lot of use. If you have it next to your house, there is easy access to water and electricity. On the downside, there are those limitations with ventilation and temperature control. They can affect your success with your plants’ survival.
Attached Even-Span Greenhouse
The attached even-span greenhouse is the one you likely think of first. This type attaches at one end to an existing building. It’s larger than a lean-to, so you’ll have plenty of room for growing a host of plants. The greater amount of space will mean a higher cost to heat it during the cooler months of the year.
Naturally, it’ll cost more because it’s bigger. You’ll have to opt for more durable materials because of the added wind resistance too. Think of the long-term because moving it later may involve a bigger job than you may expect.
These types give you the most flexibility for placing it. You can get any shape or size that you want. They are typically even-span structures with the same height throughout it. However, those advantages come at a price. Unless you live in a warmer area, you’ll have to heat the greenhouse at night and during the cooler months. That will increase your initial investment.
A cold frame is the ideal solution if you have a limited amount of space. The shape of it resembles the cellar doorway that you may see on older homes. It is a triangle-shaped wedge that is taller in the back than the front. Usually, it has just a dirt floor with a hinged top. It sits up against your house or another building for protection.
They are smaller in size though they function much like a regular greenhouse. Ventilation comes from the open panels that you can prop open to allow air flow for temperature control. It provides a great way to give seedlings a head start before you transfer them to the bigger garden. You can also use them to grown cold crops like lettuce or carrots.
A hotbed is similar to a cold frame except that the box is heated by steam or electricity. As you may guess, it’s a more elaborate setup. It is suitable for smaller sites because of the added expense of heating. The temperature inside of it doesn’t need to be much warmer than 70 degrees Fahrenheit despite what the name implies.
Design and Materials
When considering the design of your greenhouse, take into account how you plan to use it. That can help steer your course when navigating through the different features and options. Think about the number of plants you’d like to have to determine the size you should get. Each pot is going to need a circle of space around it for adequate air movement. Don’t forget about your ability to get to all them for watering and maintenance.
Types of Frames
The frame you choose can add to the strength of your greenhouse. Of course, space and placement are the main things to consider for this feature. The most popular choices are:
- Rigid frame
- Panel frame
- Gothic frame
You can get just about any size you want in these styles. The assembly will vary with the Quonset being the easiest to put up to the panel frame requiring more advanced carpentry skills.
You’ll find several options for the frame of your greenhouse that vary in strength, weight, and long-term durability.
Common options include:
- Galvanized steel
- Solexx composite
You’ll find that you need to several factors into your choice of a frame material.
Aluminum offers both an affordable cost and a lightweight design. Also, they won’t rust. However, they may not be the best choice if you live in a northern climate that receives heavy amounts of snowfall.
Galvanized steel is stronger, but it’s also heavier. Compared to other materials, it is less expensive. The other thing to remember is that it will rust over time once its protective coating has worn off. That may happen sooner rather than later, especially if you live in an area of high humidity.
Wood is an excellent choice if you’re looking for something more decorative. Look for greenhouses made with cedar or redwood for protection against the elements. It does have a limited lifespan even if you go with one of these types of wood. You can prolong longevity by applying a sealant to the structure every few years. It’ll give some new life with a splash of color.
Finally, there is Solexx composite which combines the strength of steel and composite tubing with the cost-savings of PVC. This material provides outstanding durability and insulating ability. It costs more but may offer a reasonable option for year-round use.
Plastics share some of the advantages of low cost and easy installation with aluminum frames. If you want a portable greenhouse, a plastic frame makes sense. It’s a fine option for smaller projects like cold frames. It does, however, have one glaring disadvantage. This material will deteriorate over time with UV light exposure. Suffice to say that it has limited applications.
Important Aspect When Choosing a Greenhouse
That brings up an important aspect of choosing a greenhouse. You should consider the year-round weather conditions when making your selection. Also, think about whether you’ll use it all year or just during the growing season. Of the types considered, Solexx composite has the longest lifespan and plastics, the shortest.
Glazing refers to the material that covers the frame of your greenhouse. When selecting a type, look at its thermal insulation or R-value. You’re likely familiar with this term if you’ve ever added insulation to your home. It describes how well a material will keep the heat inside of the structure. The higher it is, the better for you and your plants.
Common materials include:
- Multi-wall polycarbonate
- Polyethylene film
You may find some products that mention a U-value too. This figure measures how well a material transmits heat, making it the inverse of the R-value. In this case, the lower it it, the better. You also should look for the light transmission percentage of the glazing. It tells you how much light will pass through it and make it to your plants. Again, you’re looking for a product with a higher number.
Like the frame material, the glazing has a lifespan too. Some materials are better able to withstand the effects of the elements than others. Glass will last the longest and polyethylene film, the shortest, barring unforeseen occurrences. However, that’s only the tip of the iceberg.
Glass is likely the first thing that comes to mind when you think of what a greenhouse should look like. There are good reasons for that. It lets all the sun inside. It doesn’t expand like other materials. On the other hand, it is heavy. And unless you get tempered glass, there is always the risk of broken panes.
Aesthetically, glass looks great too. Unfortunately, it doesn’t do the best of jobs when it comes to insulating. That can be a major downside when you to other features of a greenhouse such as heating. You can get glass with insulating properties only at a price. That feature can double or even triple your cost.
Fiberglass offers the light transmission of glass without the added weight. It is stronger and impact resistant. You’ll need to get a good grade of materials, or it’ll end up becoming discolored over time. That will, in turn, affect the light penetration. You should get only clear or translucent fiberglass for optimal results.
Fiberglass trumps glass when it comes to heat retention. However, glass has the edge for longevity. You may find you’ll need to replace fiberglass after about 10 years. The end will come sooner with greenhouses in areas with full sun for a greater part of the day.
Multi-wall polycarbonate strikes a nice balance between light transmission and durability. It has a high R-value which makes it stand out for its energy efficiency. Unlike glass, it is impact resistant. However, it can scratch easily. While it lasts long, polycarbonate can yellow with age. It has a similar longevity as fiberglass.
You’ll find it as single, double, and triple-walled sheets. The higher the number of layers, the better is the insulating ability. Of course, that will add to the cost. If you live in a northern climate, you may find it’s a worthwhile investment when you take into account your heating expenses.
Polyethylene film is the least expensive of the glazing options, making it a good choice if you have a limited budget. It’s easy to find which is a nice thing. Unfortunately, it doesn’t have the longevity of the other choices listed above. You may find that you’ll have to replace it in just a few years. It also doesn’t have the superior insulating ability of other materials.
However, it’s a good choice for smaller projects like a cold frame. Even if you have to replace it every three years or so, it won’t break the bank to swap out new material. It’s a smart option if you’re just getting started and want to see if you’ll enjoy having a greenhouse.
If you live in the northern part of the country, you’ll need to add insulation to your greenhouse to use it the entire year. It’s also a cost saving measure if you have a freestanding unit that you have to heat. It doesn’t need to be anything fancy. Some well-placed hay bales can do the job quite well.
The temperature in your greenhouse should not go below 40 degrees Fahrenheit. If nighttime temperatures dip below 0 degrees, insulation is a must-have. Also, consider the R-value when choosing the material. You may find that a combination of features can maintain the recommended range of 40 to 85 degrees Fahrenheit.
You’ll find that temperature control is one of your biggest challenges, especially with smaller greenhouses. Depending on your setup, a couple of roof vents may suffice since heat will travel upward toward the peak. They are more useful than side vents which won’t allow for as much air movement. There’s also a risk of harming plants if temperatures fall below their extreme temperature hardiness.
Installing circulating fans is an excellent way to maintain proper air flow and temperature the entire year. Not unlike a ceiling fan, it can cool things down in the summer and get warm air moving around during the winter. You should place the fans in such a way that it creates a circular flow of air inside the greenhouse. Plan on running them the entire winter.
Even if you have vents on your greenhouse, you should still install a fan as a backup to ensure proper air flow. A smaller one can get the job done. Bear in mind that the winter sun at the right angle can heat up a greenhouse too.
Your choice of heating depends on your budget and the size of your greenhouse. Even with ample sunlight, it’ll still get cold at night, especially if there isn’t enough insulation to retain the heat. You can opt for a low-cost solution like a space heater or something more elaborate like a forced-air furnace. Safety is the primary factor to consider with whatever source you use.
No matter what type you use, ventilation is a must to protect both you and your plants. The technology for these products has taken them to the next level. You can get models with a built-in thermostat for an eco-friendly option. You also might consider one with a fan to do double-duty for circulation too.
The disadvantage lies in cost. Using an electric unit will add up over time. Other models such as coal or kerosene carry an added safety risk. If you go this route, it’s imperative that the air circulation is adequate and that the unit vents outside.
Forced Air Heaters
Forced air heaters offer similar advantages as a space heater with an electric fan. They provide an excellent way to ensure that there aren’t any cold spots in your greenhouse. Of course, these systems are a costlier investment. Other options include steam or hot-water systems.
Tips for Having a Greenhouse
The things that can make having a greenhouse less than fun are often factors you can avoid with some careful planning. If your budget allows, try to make its maintenance as automated as possible. Use the advent of smart technology to your advantage. Look for accessories such as heating and ventilation that are automated.
A thermostat is a godsend when it comes to keeping the optimal conditions in your greenhouse. Manual-cranking vents may save you some cash, but you may find your savings don’t add up to much with the added expense of new plants. The same thing applies to ventilation. The conditions can change rapidly in a smaller unit, putting your plants at risk. Consider adding features such as solar-powered autovents.
You can also find similar automated devices such as misting systems. They can ensure that the humidity stays at least 50 percent to keep the plants from drying out on warm, sunny days.
Choose Your Flooring with Comfort and Practicality in Mind
Flooring may not be high on your list of considerations, but it’s something you should think about carefully. It should provide a comfortable walking surface that is easy to clean. It should also handle water all right. A poured concrete floor is the obvious choice, but you can opt for something more pleasing to the eyes such as brick or stone.
You should take the same precautions to prevent weeds as you would in your garden. That means laying landscaping material or plastic on the ground before you add your flooring material. Remember, the purpose of your greenhouse is create the best environment to grow plants.
Save Your Back with a Workbench
A workbench is another must-have in a greenhouse. That’s your command center when it comes to transplanting plants or any of the other chores you’ll have to do. Do yourself a favor and buy or make a bench. You can add a shelf to it to store your tools when not in use. The area underneath it can also provide a bit of welcome shade for delicate plants.
Buying a greenhouse can take your gardening to the next level. However, there’s a lot more to it than picking out the prettiest one. There are also practical considerations that you need to research that go beyond deciding where to set it up in your yard. Your budget is the main driving factors. However, you need to weight the pros and cons carefully when reviewing the full picture.
Your costs will extend past your initial investment. Your choice of materials, size, and accessories will make the difference between a successful venture and one that fails. While it may seem like a lot of work, it is a wiser course of action to consider all your option and how they will affect the bottom line.