WHAT ARE THE DIFFERENT TYPES OF GREENHOUSE STRUCTURE?
It is extremely important to choose or to build a greenhouse for your property to take the maximum advantage of the available sunlight.
This depends on the right choice of the greenhouse structure. I am going to give you a detailed overview of the greenhouse types available along with their advantages and disadvantages.
There are following types of greenhouses:
Lean-to
Even-span
Uneven-span
Quonset/Hoop-house
Gothic arch
Conventional/Post-and-Rafter
A-frame
Cold Frame and Hotbed
… and many more!
Before choosing a shape bear in mind that you can set up an attached or a freestanding greenhouse. What is it and what is the difference?
ATTACHED GREENHOUSE
Attached greenhouse as the name suggests is attached to the building. One of the striking pros of having this type is in using not as much building materials as is required for a freestanding structure.
Also, the heating and ventilation tools can be used to maintain your home. However, it comes with a major drawback in terms of controlling the temperature within the greenhouse.
Also, the building can shade the attached greenhouse and limit the light required by plants.
An attached greenhouse can be in two shapes: lean-to and even-span.
LEAN-TO OR EVEN-SPAN ATTACHED GREENHOUSE?
Lean-to attached greenhouse is usually set up on the south-facing side of the building and the ridge of the roof connects to the building. This type of greenhouse is easy and cheap to heat especially if you live in a cold climate.
On the other hand, an even-span greenhouse provides more space for a plant growth. Why? Because the end wall is fully attached to the house and the rafters are of the equal length.
Another con of the even-span attached greenhouse is in the actual cost of the building and heating the construction in comparison to the lean-to type.
Therefore, you might just invest the same money into a freestanding greenhouse. However, don’t forget that water and electricity are easily reachable when the greenhouse is in the building.
To sum up, both lean-to and even-span attached greenhouse structures encounter the same problem – shadowing. The shadowing of the house they are attached to leads to the reduction of sunlight.
WINDOW MOUNTED GREENHOUSE
I came across this construction recently. This structure attaches to the window frame on a south-facing side of the house wall.
It is a good option for a gardener with a limited space or for someone who lives in a flat and wants to grow some herbs throughout the year.
Moreover, the structure is very little and compact, easy to heat and inexpensive to maintain.
FREESTANDING GREENHOUSE
Similar to the attached types, freestanding greenhouse can be in even-span and lean-to shapes. I am going to compare these two first and then move onto describing further freestanding models.
WHAT IS THE BEST SHAPE FOR A GREENHOUSE?
EVEN-SPAN FREESTANDING GREENHOUSE
The structure is characterized by the equally sized rafters, roof truss and self-supporting construction.
You can easily recognize it by a traditional gable (a triangle between the sides of the sloped roof). It is the most common type of greenhouse because it utilizes the maximum amount of sunlight.
Also, lots of space allows growing wide range of plants whilst maintaining the best conditions. However, even-span type usually requires floor-to-ceiling glass panels and aluminum frame for an extra support.
UNEVEN-SPAN FREESTANDING GREENHOUSE
It is a complete opposite of the even-span type as the rafters are unequal and the structure is not self-supported. This is ideal to be built on a hillside placement.
The advantage of the lean-to freestanding greenhouse is in the maximization of the sunlight but the disadvantage is in the difficulty to work in it due to the limited space and orientation of the greenhouse.
Okay, now let’s move to the next types.
QUONSET/HOOP-HOUSE GREENHOUSE
This structure is characterized by a curved roof and military hut-style design. The hoops are usually made of aluminum or PVC pipes and glazed with a polyethylene film or panels for a better insulation.
The sidewalls are set up quite low which limits the storage space and headroom. This is probably the cheapest and easiest type to build that’s why I like it.
The characteristic hoop appearance is very useful to roll off the accumulation of snow and water from the top.
GOTHIC ARCH GREENHOUSE STRUCTURE
This is the most aesthetically pleasant structure of the greenhouse I have ever seen (my personal choice). The design is characterized by the walls bent over to form a pointed roof inspired by the windows of the Gothic cathedrals all over the world.
It is quite a wide greenhouse and is convenient for anyone who wants to grow plants in the rows, on the shelves and hang the pots within the same structure.
It is very similar to the Quonset type and carries the same functionality described above. Also, it is heat conservative because of the minimal heat exposure.
A-FRAME GREENHOUSE STRUCTURE
In my opinion, it is the simplest and easiest structure to set up and it looks really cute as well! The design lets you to save up on the construction materials and is perfect for a little backyard garden.
All you need to do is to combine roof and sidewalls together to form a signature triangular structure. The major drawback which you might encounter is a poor air circulation in the corners.
CONVENTIONAL/POST-AND-RAFTER GREENHOUSE
I think that post-and-rafter greenhouses are quite popular as many gardeners go specifically for this type. Why? Well, the construction is relatively simple and is probably the strongest one out of all types.
This is due to the rafter which provides extra support to the roof especially during the winter. However, it makes the whole construction heavier requiring a strong frame which is more expensive.
COLD FRAME, HOTBED AND MINI GREENHOUSES
These are the basic greenhouses. Don’t confuse them with a term a mini-greenhouses. Mini-greenhouses are glazed homemade or professional boxes.
These can be either tall or short and can be oriented vertically or horizontally. That is a good example of a mini-greenhouse. It is ideally designed for seed starting.
What is a cold frame? It’s basically a ventilated box which is placed flat on the ground and has a glazed, sloping lid. It is perfect for raised beds in the spring to warm up the soil.
What is a hotbed then? In simple words it’s a heated cold frame. The heating methods vary from using light bulbs, hot water and steam to manure and electric cables.
So, choosing which one you need depends on the vegetables you want to grow.
WHAT CAN YOU GROW IN A HOTBED?
Cold frame is ideal for cold-loving plants, for example cabbage, broccoli and cauliflower. If you are planning to grow heat-loving plants like peppers, tomatoes and eggplants a hotbed is a perfect option.
Once you made up your mind about the greenhouse structure you can start thinking about frame and glazingmaterials.
So, these are the main types of greenhouses please let me know in the comments which ones do you like or which greenhouse structure you have in your backyard.
WHAT ARE THE GREENHOUSE LIGHTING REQUIREMENTS?
Greenhouse requires light to promote crop growth and yield. Also, it plays an important role in photosynthesis. In summer it is crucial to provide enough shade for the plants. On the other side, in winter greenhouse lighting requirements change because low light along with low temperatures can cause plant growth to slow down.
HOW MUCH LIGHT DOES A GREENHOUSE NEED?
A greenhouse needs at least 6 hours of direct sunlight per day. To get the most of the sunlight site your greenhouse east to west, that way the largest side will get the most sun exposure. Make sure to keep the windows clean in winter. Remove the dust regularly as it is proved to increase the light intensity by 10%.
DO YOU NEED A GROW LIGHT IN A GREENHOUSE?
Majority of gardeners rely only on natural light and don’t need a grow light in a greenhouse. However, if you plan to grow plants in winter, then you might need a grow light in a greenhouse. A grow light is an electric light which is specific to a light spectrum appropriate for photosynthesis.
Whether you need a grow light in a greenhouse depends not only on the time of the year but on the type of crops and how much sunlight is available.
You have to be very careful when choosing grow light for a greenhouse. The most common problems growers are running into include the lack of light, the light is of a wrong kind, the distribution of the light is not even or there might be too much of it.
WHAT KIND OF LIGHT DO YOU NEED TO GROW PLANTS?
An artificial light to grow plants should provide a balance of cool and warm light that replicates the natural sunlight. That kind of light is perfect for flowering plants.
Depending on the type of the plant, stage of cultivation and photoperiod required, you will need a light with a specific spectrum range. A light spectrum is the collection of different wavelengths of energy produced by a light source.
In the visible spectrum of light, the color of light depends on the frequency. Different color of light helps plants to achieve different goals. When buying bulbs you can see the numbers 2700K and 3000K. It refers to the coolness and warmth of the light spectrum.
Plants need shorter, warmer wavelengths of light which are in the blue spectrum when growing and maturing. Alternatively, plants need longer, cooler wavelengths of light in the red and orange spectrum for blooming and production.
WHAT KIND OF LIGHTS ARE USED IN GREENHOUSES?
There are four types of lights that can be used in greenhouses:
- Incandescent light
- High intensity fluorescent light
- High intensity discharge (HID) light
- Light emitting diode (LED) light
INCANDESCENT LIGHT BULBS FOR GREENHOUSE
Incandescent light bulbs are electric lights which heats up to a temperature high enough to make it glow with visible light. Because of the heat they produce you must not place them close to foliage. It is a good option to increase the day length.
Unfortunately, they don’t provide sufficient light for most greenhouse applications. It is a very easy lighting option to install and it is a good source of red wavelengths.
HIGH INTENSITY FLUORESCENT FOR GREENHOUSE
In comparison to incandescent bulbs, fluorescent light is more efficient in converting electricity into light without waste of heat. The color spectrum of standard cool white fluorescent bulbs is high in blue and low in red. Although, they do provide a full white light spectrum.
A standard fluorescent bulb knows as T12 is sufficient for houseplants, starting seeds but is weak in light intensity. A narrower T5 provides three times more light than T12 and is in both warm and cold spectrum.
Fluorescent light is a good option for a greenhouse with low natural light. It is also suitable for the propagating areas or growth rooms. Large spaces can benefit from fluorescent bulbs efficiency.
LED LIGHT FOR GREENHOUSE
LED lights are more expensive to purchase than fluorescent light but use half the electricity and last up to five times longer. Also, their light intensity is far greater and they come in full spectrum light. LED lights are small in size and are really easy to install.
WILL LED LIGHTS HELP PLANTS GROW?
LED lights help plant growth because they maximize blue and red lights to provide a balance for plants. They don’t provide green and yellow light and only optimize the light spectrum appropriate for photosynthesis. LED lights are helpful in all stages of plant growth.
WHAT LIGHT SOURCE IS RECOMMENDED FOR A GREENHOUSE?
HID is a recommended light source for a greenhouse as it is very economical. Many growers opt for HID as the best lights to provide supplemental greenhouse light. These lights are very efficient at converting electricity to light and are good at increasing light intensity.
There are two types of HID:
- High-pressure sodium (HPS) bulbs – these are rich in red spectrum and are used to promote growth and flowering.
- Metal Halide (MH) bulbs – these provide more blue light and are ideal to support vegetative growth. Use them in the early phase of plant’s life. In comparison to HPS, their spectrum is more balanced.
However, there are two disadvantages with this light source. First, you need to install them on the large heavy ballasts which come separately from the light fixtures. These ballasts are quite bulky and take a lot of space, so it is not as practical as in comparison to small-sized LED lights.
Second, HID lights produce a significant amount of heat. Therefore, you need to place them 30-36 inches (76-91 cm) away from the plants which effects the lighting efficiency. Also, in comparison to other options, HID lights are more expensive to operate.
