What is a Greenhouse?
In Mulberry Greenhouses, we don't believe that any question is a silly question, but it’s important that we lay down some definitions before we start. There is a surprising amount of confusion and even misinformation out there regarding what is and what isn’t a greenhouse.
The definition of a greenhouse according to wikipedia is:
a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.
And, yeah, that’s pretty much the only criteria.
People might argue with you if you say it, but the truth is that “greenhouse” is a catch-all term. It describes any structure that’s transparent and meant to aid in growing plants. There are several sub-types of greenhouse that have clear definitions distinct from one another, but the huge variety of products and designs available means that they blur together pretty often.
Types of Greenhouses
There are several structures that often get lumped together and called greenhouses. To be fair, they’re mostly the same with only one or two differences.
If you want to be very, very technical in a way that is completely unnecessary, a greenhouse would be a structure with:
- transparent walls and roof
- no heating
- a ventilation system
If you wanted to be even more pedantic, you could expound upon the heating by saying no powered heating systems. There are lots of ways to keep a greenhouse warm, from shutting the vents, to using insulation, to keeping barrels of water as “thermal batteries” to release heat overnight. If you put a space heater in there, however, it would turn into a hothouse.
Greenhouses are typically relatively large. If it’s smaller than 8 ft by 8 ft it’s almost certainly a coldframe. The larger the structure is, the better able it is to capture and store heat. Possibly too good at storing heat, to the point where it may be to hot for the plants inside or too humid. That’s why greenhouses always have ventilation, whether it’s windows or vents that open to allow airflow or a fan that circulates air while keeping the structure sealed.
Same as a greenhouse but with a heater
A hothouse is just a greenhouse with a powered heating system, really. They can still come in practically any shape or size.
Unlike greenhouses, a hothouse maintains growing temperature year round. Usually this is accomplished through an electric or gas heater similar to the ones that heat homes. Some (really awesome) greenhouses use geothermal energy from the Earth or recycle heat energy from manufacturing facilities located nearby.
Practically all commercial growing operations (and many home growers!) use hothouses in some form or another. It’s the only way to continue production throughout the changing seasons. Even if you live in a desert where heating is unnecessary you’re likely to find hothouses rather than greenhouses simply because they allow you to keep plants in exactly the optimal growing conditions.
If you want to keep calling your hothouse a greenhouse, it’s OK. We won’t tell.
Gardening screenhouses are rarely intended for the plants – usually it’s for the comfort or ease of the gardener. They are exactly what they sound like: a (usually opaque) canopy with walls made of mesh or screen. Screenhouses severely limit the amount of light that reaches the plants beneath. It’s only suitable for shade-loving plants.
The purpose of a screenhouse is to keep pests out, anything from mosquitoes to rabbits to deer that might threaten your plants. More often than not, the actual use of a screenhouse is a temporary structure to allow people to enjoy the outdoors (either camping or in a backyard) without the annoyances that nature often brings.
The coldframe is the single biggest contributor to greenhouse confusion. The reason is simple – they’re cheap. Almost every “greenhouse” sold for less than a couple hundred dollars is not really a greenhouse, it’s a cold frame.
The difference is twofold. Coldframes are never heated, hence the name. They tend to only be 5-15 degrees F warmer than the outside. Their purpose is not to grow plants in – it’s meant to extend the beginning or end of the growing season by a few weeks. You can start your seeds in a coldframe early in spring without being worried about an unusually cold night, or you can eke an extra couple weeks of production out of a summer crop when fall starts threatening frost.
Coldframes are also not ventilated, which is what distinguishes them from a greenhouse. In general, they are too small to have ventilation while remaining warm (because the volume of air is too small to retain warmer temperatures if it mixes with outside air, unlike in a larger greenhouse).
A croptop is a temporary, mobile structure that is pretty different than other types of greenhouse. I’d hesitate to even call it a greenhouse because, as the name suggests, they usually don’t have walls.
Essentially, a croptop is a clear umbrella you place over plants with the intention of protecting them from rain or possibly dimming very harsh sun. Many croptops come with a detachable curtain or skirt that can be used to add walls as necessary.
It’s a pretty niche product that’s even more temporary than a coldframe. There aren’t many applications other than, say, protecting outdoor succulents from spring showers.
What are the Pros and Cons of a Greenhouse?
As a grower, I’m biased. I admit it! Looking at it from the perspective of my plants, there are only pros.
Objectively, though, there are ups and downs to every method of growing plants. Having a greenhouse is much more involved than throwing some annuals in the dirt; it comes with added responsibility. Here’s the breakdown of the advantages and disadvantages of greenhouses.
🌳 Advantages of a Greenhouse
1. Grow Plants Happier, Healthier, and Easier
Plants always seem to do better in a greenhouse! At least, all of the pictures of greenhouses that I see have gorgeous, lush plants spilling out of their containers and threatening to take over the whole building.
It’s kind of a chicken and egg question. Do greenhouses make plants grow better, or do only people that are good at growing (and thus dedicated) buy greenhouses?
It’s a bit of both, I’m sure, but it’s certainly true that greenhouses make caring for plants easier. With light and temperature mostly consistent year-round, the only thing you are really responsible for is watering correctly. The plants are stable in their optimal conditions perpetually!
2. Have Access to Fruits and Vegetables Out of Season
Anyone who has ever grown their own salad will agree – the “fruits” of your labor are infinitely sweeter than store-bought food.
And once you’ve known the pleasure of eating grape tomatoes off the vine it’s genuinely disappointing to buy them from the grocery store when fall rolls around. Not to mention you finally understand the implications – if you have access to these foods out of season, it means they were grown somewhere far away and shipped to you.
Many people get started with a coldframe so that they can get the green beans started earlier, then the very next year they’ve upgraded to a full greenhouse. It’s a slippery slope!
3. Control Pest Populations Easier
No one tells you about the horrors of aphids and the tyranny of mealybugs before you start gardening. What’s worse is that, if you aren’t the type to inspect each individual plant every day, an infestation can go from a few leaves on a single plant to your entire garden being threatened in the blink of an eye.
One of the most underrated benefits of greenhouses is that they’re insulated from the outside. It’s extremely unlikely that a pest will get in by itself. Almost every pest in a greenhouse is introduced by bringing in plants that are unknowingly infected.
The danger of mystery plants is easily solved by quarantining them by themselves for a couple weeks. Any latent problems should show themselves by then so you can deal with it appropriately.
🌳 Disadvantages of a Greenhouse
1. They’re Expensive
It’s true. Greenhouses aren’t cheap. Sure, there are some affordable options – those big 8’x 8′ coldframes are almost a greenhouse. They’ll probably scratch the itch. It’s not quite the same, though.
The cheapest “real” greenhouses will run you at least $500. For some people, that’s a big investment for an otherwise cheap hobby. And, like many expensive investments, they have upkeep costs. An electric fan ventilation system will run almost continuously – your electric bill will be impacted. If you heat the greenhouse it can really start to be pricey.
2. Required Maintenance
Greenhouses are actual buildings. In order for them to remain functional and effective (not to mention attractive), there’s a fair degree of ongoing maintenance that will be necessary.
Yeah, there’s the obvious stuff like sweeping the floors, disposing of dead plant matter, cleaning out cobwebs and the like. But you also need to inspect the walls to make sure they’re sealed and not letting air escape. You have to keep the roof clear of dust and debris so that light can penetrate. You need to ensure the ventilation and heating systems are running smoothly. Heck, you have to watch the foundations you poured to make sure they don’t crack or sink!
Greenhouses aren’t really like that old shed in the backyard. They’re a living building – in no small part due to the living plants inside them. The building has to be taken care of just like the flowers.
3. They’re Immobile
Depending on where you are in your life, this may or may not be an issue.
If you’ve settled down in the home you plan to live in the rest of your life – no problem! Get a greenhouse. Get ten!
But there are many gardeners that aren’t quite at that stage in their life. Even if they have the space for the greenhouse, they can’t bring it with them when they move. Coldframes and the like can be disassembled and transported, but a real greenhouse has concrete foundations poured and a building built on it. That’s not going anywhere.
How to Purchase a Greenhouse
Surprisingly, buying a greenhouse is easier than ever. Just like you used to be able to order a whole house from a Sears catalog, you can order a whole greenhouse from the Internet. It’ll be shipped in pieces and parts, of course, so I hope you don’t mind “Some Assembly Required”!
Before you get ahead of yourself and impulse-buy a greenhouse, it’s important to be aware of the full costs of owning one. Much like purchasing a car, the sticker price is far from the total price of having and using it. There are ongoing costs, additional equipment required, site preparation costs, and more!
That’s not to say that buying a greenhouse necessarily has to be a very expensive or very arduous process. It just pays to know what you’re getting into!
🌳 Greenhouse Costs
Upfront Costs of a Greenhouse
How much does a greenhouse cost? It’s usually more than the sticker price.
Some common expenses for greenhouses include:
- The cost of the greenhouse. It varies widely, but greenhouses can be as cheap as $100 for a very low-tech backyard solution or millions of dollars for a space-age industrial farm greenhouse with all of the bells and whistles. Realistically, a mid-ranged backyard greenhouse will be around $1000-$3000 for a quality building.
- The cost of site preparation. A greenhouse is a permanent structure. You have to prep the site by clearing existing plants, flattening the land, laying foundation, and often pouring concrete. If there will be running water and electricity, those utilities have to be routed to the greenhouse in advance.
- The cost of construction. If you purchased a DIY greenhouse kit, the only cost will be your time (which does have a dollar-value!) and maybe pizza and beer for the buddy that helps out. If you’re having a contractor or company build it for you, construction costs may or may not be built into the total price. While labor can often double the price of construction, greenhouses are fairly simple so it shouldn’t be overly expensive. Expect to pay at least $30/hour if using professionals to build a greenhouse.
- (Sometimes) The cost of permits and licenses. In most cases, you can build a greenhouse on your property without anyone’s permission. Some municipalities, however, have strict regulations on permanent structures and it may require you to fill out forms (with filing fees) or apply for licenses or permits.
Hidden Costs of a Greenhouse
Much like buying a car, there are a lot of costs that are often overlooked in your initial excitement. These costs vary greatly depending on how big and complex your greenhouse is.
- The cost of necessary equipment and accessories. Before you can get to the fun part of spending your money on plants, you’ll first have to purchase the equipment necessary to keep them alive. At the minimum you’ll need a ventilation system. Vents and windows come with most greenhouses, but they’re rarely sufficient without fans to help them along. Most climates will require a heater for the winter (and if it uses natural gas instead of electricity it will be an additional expense to run a line out). Most greenhouses will use supplemental lighting during darker seasons. Grow lights ain’t cheap. The racks or tables for the plants can be built, but lumber isn’t cheap (and it does eventually degrade in the climate of a greenhouse).
- The cost of ongoing maintenance. A greenhouse is a house for plants. Plants, surprisingly, require many of the same things and make many of the same messes. You’ll need to clean the greenhouse often or it will quickly become a dirty, musty, moldy, unpleasant place for you and the plants. Time is a large cost, but so are cleaning supplies (such as ladders and extendable wipers to reach the exterior roof panes).
- The cost of utilities. Greenhouses need water at the very least. If it’s a small structure with few plants, it might be feasible to just carry a watering pail with you. If the greenhouse is near enough to an outside spigot you can run a hose inside. Otherwise, you’ll need to set up water lines. Electricity will almost certainly be necessary – for light, for heaters, for fans and ventilation systems. During extreme temperatures, the electricity cost can be significant.
WHERE TO BUY A GREENHOUSE
Mulberry Greenhouses offers a variety of greenhouses. Mulberry Greenhouse only deal with manufacturers that are reliable and offer high quality. When you buy from Mulberry Greenhouses, you will be offered the best customer service, most reliable products with free shipping, tax free and on top of it all, we offer Price Match Guarantee.
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