Greenhouse Planning

As you do your greenhouse planning here are some questions you should consider:

What type of greenhouse structure do you want?

Attached Garden Sun Room greenhouseA GREENHOUSE is for plants that need a different environment than what is outside. The plants you grow affect the design and equipment you need.


A GARDEN ROOM/ SUN ROOM combines a gardening greenhouse and incidental living space (spa enclosure, sitting area, etc).Tudor style greenhouse with gable end attachement


A SOLARIUM is designed for primary living space, usually an addition to your house.


Where should you put your greenhouse?

Small Solite Greenhouse next to a deckWhen doing greenhouse planning, questions to ask are: How would a greenhouse best fit with the landscape? Is it convenient? Exposure to sun, wind and weather?  Generally a southeasterly exposure is best, with east, south and west exposures following in order. Should the greenhouse should be free-standing or attached to your house? For attached greenhouses, issues such as the height of the attachment wall, snow avalanching off the roof onto the greenhouse, icicles, etc. need to be considered. Attached greenhouses frequently have building code issues as well.

What size greenhouse do you need?

16' wide greenhouse with double doorssAs you plan, select a greenhouse as large as your site and budget allow since gardeners usually wish they had more space. Consider the footprint as well as height for your comfort and to provide room for tall and hanging plants. (Often a greenhouse less than 200 sq.ft. does not require a permit – especially if it is free standing.)

Which greenhouse framing materials should be used?

Milled Redwood for greenhousesGreenhouse framing material options include wood, aluminum & plastic. Plastic is for short-term, temporary greenhouses. Aluminum is durable if properly finished but is not environmentally friendly. Wood is renewable and sustainable, with a natural beauty that fits well with residential architecture. Clear Heart Redwood is naturally rot resistant.  Wood is more heat efficient than aluminum (1400 times better). Plus, a wood greenhouse frame allows easy addition of accessories such as shelves, hooks, and hanging bars.

Which greenhouse glazing materials should be used?

Glass walls, twin wall roof

Glass walls, twin wall roof

Greenhouse glazing can be glass or plastics. Glass is strong, economical, attractive, and long lasting. If there is a high risk of breakage or safety glazing is required, tempered glass or twin-wall polycarbonate can be used for the greenhouse glazing. Twin wall is energy efficient but is not clear. We prefer clear walls and twin wall roof.

How to control the greenhouse environment?

In this video, Rick Warner talks about creating the right greenhouse environment

A greenhouse has a different environment than what you have Greenhouse jalousie windowoutside. Each gardener’s needs vary with the plants they grow. 5 basic environmental factors should be considered in your greenhouse planning: ventilation, heat, circulation, shade and humidity.

Bayliss Greenhouse Solar Vent OpenerGreenhouse Ventilation: A natural, effective way to ventilate a greenhouse is with vents. Roof vents plus base wall vents and/or Jalousie (louvered) windows, helps cool air flow into the greenhouse down low as hot air exits through the roof vents. Gentle ventilation helps preserve the humidity that plants love. Fan venting systems move air effectively but are noisy and dehumidify the greenhouse during dry weather. Roof vents can be automated (see solar powered vent openers) for easy operation.

Accessories for greenhouseHeating Your Greenhouse:  Gas (natural or LP) or electric (120V or 240V) heaters can be used. Heater size depends on size of the greenhouse, the desired inside temperature and the outside conditions involved.

Air Circulation in the Greenhouse: Air movement is essential for a healthy greenhouse environment, reducing heating costs and condensation. We recommend gentle air movement running 24/7. Especially important in the winter when humidity is high and conditions are ripe for mold and mildew.

Greenhouse with shade clothShading the greenhouse: We recommend custom-fit shade cloth panels. Attached to the outside of the greenhouse, shade cloth is effective, neat, economical and reusable. Shade cloth can be attached to the inside of the greenhouse but outside panels are more effective at keeping the heat out.

Humidity in the greenhouse: Wetting down a porous floor (such as bricks on sand or gravel) is an effective method for creating humidity in a greenhouse. An automatic humidifier or a misting/fogging system may also be used. During hot summer conditions a combination of shade, ventilation and humidity is key for keeping your plants healthy in the greenhouse.

Engineering considerations for your greenhouse?

Well designed greenhouseHow will you use your greenhouse? As a temporary, springtime shelter designed for starting a few flats of seeds, or a year-round, permanent structure? A year-round greenhouse must be designed to handle a harsh environment both inside and out. The greenhouse frame should be durable. Joints and other points of attachment should be solid, weather-tight, and blocking as little light as possible. A greenhouse full of plants will have condensation. A smooth inside roof surface and sufficient roof pitch will help prevent water dripping you and your plants. Adequate height should be part of the greenhouse design, not only for hanging plants but your comfort as well.

Foundation Considerations?

Trillium greenhouse foundationA firmly anchored, level and straight foundation keeps the greenhouse structure where it belongs. Generally a 6” perimeter foundation, approximately 4” above grade, with a depth below frost level will suffice. Greenhouses not anchored to the ground might be lost in a strong wind.

How do you deal with Building Codes?

Greenhouse building codes are confusing
Local codes and code interpretations vary greatly between areas, and even within offices, so it is the responsibility of the buyer to ensure compliance. Usually a freestanding greenhouse smaller than 120 sq ft (and in many communities up to 200 sq.ft.) does not need a permit. For larger units, and attached structures, should you choose to obtain a permit, get it before your greenhouse is manufactured in case there are extra requirements, such as bracing or safety glazing, to be met. We will help as best we can.