Pros

Design

With a freestanding Greenhouse, you are limited only by the imagination when it comes to style or shape.

Flexibility

Can be oriented to the sun to maximize the amount of light received

Location

It can be located just about anywhere but sheltered from winter winds, have well-drained soil, and be easily accessible. Placed near the garden as part of the landscape, will make it easier for the deployment of flowering plants and seedlings in the spring.

Expandable

If more space is required it can be expanded as needed.

Size

Well, an attached greenhouse is limited by the building it is attached to, freestanding greenhouses can be as large as you want.

Cons

Distance

You will need power and water supplies transported to the greenhouse. The digging of a ditch may be necessary to lay water pipe and power, below the frost line, or using an extension cord for electrical power, not a good option in the winter months. The commute to and from the greenhouse, multiple times per day, will require more energy compared to an attached greenhouse.

Inconvenience

If you live in a climate where it snows in winter, your greenhouse is more likely to get buried after a heavy snowfall requiring extra motivation to get out there to clean it.

Heat Loss

High heat loss is experienced by freestanding greenhouses as all sides are exposed to the elements. An effective method to decrease heat loss would be it insulate the north side of the greenhouse. The addition of extra sheeting can be used as insulation, this negatively affects light levels in the greenhouse, causing plants to suffer sunburn when they go outside in the spring.

Security

Theft is a major issue do to easy accessibility of the structure. For this reason, you should keep the structure securely locked.

Pros

Daytime heat source – A source of additional heat during winter daylight hours. During the long winter nights,  it will be necessary to have shades or blinds to slow heat loss through the windows.

Insulation – Provides additional insulation for your home. Acting as a buffer between the walls of the home and the outdoors, an attached greenhouse can increase the insulation value of an exterior wall.

Humidifier – Beneficial side effect is humidity for your home during the dry winter season. Could help alleviate seasonal aches and pains caused by winter humidity drop.

Extra Space – Provides for additional living space, adding a few hundred square feet to your home.

Easy Access – It’s right there. No need to go outside. Plants can be easily tended particularly handy in the winter, no shovelling your way to the greenhouse.

Added Value – For the most part, an attached greenhouse will increase the value of your home.

Cons

Extreme Heat in the summer

All greenhouses get hot during the summer months and attached greenhouses will vent that extra heat into the house. A well-designed attached greenhouse includes ways to vent excess heat, shade the structure and close it off from the home.

Orientation

The most efficient greenhouses face due south or slightly southeast. If you cannot build on a site with southern exposure, you won’t get optimal results. If you attach your greenhouse to a wall that does not face south, which may be good for certain types of plants, it will be more expensive to heat in winter.

Potential for rot

Because plants transpire, greenhouses are humid. This humidity can get into the walls of your home and cause rot. When installing an attached greenhouse, you will need to add a good vapour barrier over the wooden walls of your home where the greenhouse is attached to prevent humidity from getting to the wood.

Insects

Insects can more easily find their way into your home via the greenhouse. If you spray insecticides in the greenhouse to get rid of them, the spray can also get into your home.

Inflexible

An attached greenhouse’s size may be restricted by the size of the space available beside your home.  This can limit your future expansion or even the size of the plants that you can grow.

Cleanliness

In an attached greenhouse, you will want to promptly clean up dropped soil lest you track dirt into your home.