Greenhouse Size: Start With Plants, Not the Structure

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Leslie Halleck, horticulturist and author of Home Greenhouse Revival, argues that the most common and expensive greenhouse mistake is choosing a size and style before deciding what you want to grow. Her approach: first identify your target plants, their temperature requirements, and your seasonal goals — then work backward to pick the right structure. A beautiful glass greenhouse may simply not maintain the environmental conditions needed for the crops you have in mind, and she says she has had to tell many people their finished greenhouse will not accomplish their goals.

Practical planning points she raised: account for all the non-plant space (benches, potting tables, soil storage, heating barrels, irrigation equipment) that quickly eats into usable growing area; consider whether you need to zone the greenhouse for plants with different temperature needs; and recognize that cooling a greenhouse in summer is significantly harder than heating it in winter — evaporative coolers and air conditioners can typically only reduce internal temperature by 15 to 20 degrees from ambient, which leaves hot-climate growers with a greenhouse that may be unusable May through August.