Design – A freestanding greenhouse can be any shape or style.
Flexibility – Can be oriented east to west to maximize the amount of light it receives.
Location – Can be located anywhere as long as it is sheltered from winter winds, where the soil is well drained, and where it is easily accessible. It can also be placed near the garden, making it easier to move plants in and out of the structure.
Expandable – If you need more space it can be expanded as needed
Size – Whereas the size of an attached greenhouse is limited by the building to which it is attached, freestanding greenhouses can be as large as you like.
Distance – Power and water will need to be brought to the greenhouse. This may require digging a ditch to lay a water pipe below the frost line or using an extension cord for electrical power. The extra distance from the home as compared to an attached greenhouse also means that it will be used less and will require more energy to go to and from the greenhouse to the house multiple times per day.
Heat loss – Freestanding greenhouses experience higher heat loss than attached greenhouses because all four sides are exposed to the elements. To most effectively cut down on heat loss you can insulate the north side of the greenhouse. Bubble wrap or layers of polyethylene sheeting can be used for insulation, though this significantly cuts down on the light levels in the greenhouse, leading to your plants suffering sunburn when you bring them outside in the spring.
Inconvenience – If you live in a climate where it snows in winter, your greenhouse is more likely to get buried after a heavy snowfall and since it’s farther away from your home you’re less likely to walk out there to clean it.
Security – More susceptible to theft due to its easy accessibility. For this reason, you should keep the structure securely locked.
Extra space – Provides additional living space, adding several hundred square feet to your home.
Daytime heat source – Source of additional heat during winter daylight hours. During long winter nights, however, you’ll need to use blinds or shades to slow heat loss through the glazing.
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 by 10 to 15 percent.
Humidifier – Source of humidity for your home during dry winter months. If you suffer from aches and pains when humidity levels drop, you may find that an attached greenhouse alleviates such symptoms.
Easy access – Plants can be easily tended to at any time without having to walk outside—particularly useful in the winter as you don’t have to shovel snow to get into the greenhouse.
Added value – In most cases an attached greenhouse will increase the value of your home.
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.
Heat in the summer – All greenhouses get hot during the summer months and attached structures will vent that extra heat into the home. A well-designed attached greenhouse includes ways to vent excess heat, shade the structure and close it off from the home.
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 vapor barrier over the wooden walls of your home where the greenhouse is attached to prevent humidity from getting to the wood.
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.
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.
Cleanliness – In an attached greenhouse, you will want to promptly clean up dropped soil lest you track dirt into your home.