Why do you want a greenhouse – what uses will it have affects the design.
Winter growing of plants in pots will warrant a South wall and roof slope exposure to take advantage of the sun.
Summer germination trays will need to have plenty of ventilation to avoid bolting.
Where will it be located – free standing requires more materials than attached to a wall.
An entrance large enough for a wheel barrow to get in makes sense but a pass through entrance on opposite sides eliminates the need to back the wheel barrow out awkwardly.
Watering supply will need to be close by without obstructing pathways.
A heat source for winter extremes may need to be added with an extension cord.
How much will it cost – esthetics or purpose? Recycled materials or quality synthetics?
How long do you want it to last?
Do you want to be able to deconstruct it and move it later on?
How big do you want it to be?
How sturdy will it need to be? Heavy rains or high winds if not in a protected location may be a problem.
Shelving is essential
- Sturdy enough to hold a germination tray full of soil and water in the base.
- Wide enough to hold at least 2 pots deep
- Another option is to have solid supports and a growing basin for scattered seedlings that have smaller root systems.
- Capable of quick drainage to avoid rot and algae/mold.
- Sizing will influence total dimensions of greenhouse.
- Pots and trays need to be stored between usages.
- Misting sprinklers built into ceiling allows for low maintenance growing on an automated watering schedule.
- Optionally a garden hose misting nozzle can be used every 2 days if humidity stays high.
- Mini hoses quick-fastened to rafter hooks can be set on a faucet timer for low maintenance growing.
- irrigation kits that use “Spot Spitters” can be used that can be staked into taller pots. The advantage is mobility and different spray patterns for plants that prefer drier conditions can be grouped together to receive less moisture.
- Drip irrigation hoses can be moved around for germination trays but become very awkward.
Roof material choice influences design
- Plastic sheeting is the ideal ceiling and wall material for the amount of light to enter in our region but is subject to damaging rips in an unprotected area.
- Plastic sheeting is easy to repair with a glue stick gun.
- Glass is very heavy and requires sturdy framing.
- Fiberglass roof panels are expensive and may need to be scrubbed clean of algae during rainy season.