Summary
Choose shelter according to the plants you want to grow, the space available and how often you can ventilate it.
If you want to harden off seedlings or protect low-growing plants, a cold frame may be enough. If you need standing space, tall crops or a covered work area, a greenhouse offers more room.
Decide what shelter
must achieve
If you want to harden off seedlings or protect low-growing plants, a cold frame may be enough. If you need standing space, tall crops or a covered work area, a greenhouse offers more room. Neither unheated structure guarantees frost-free conditions. Tender plants may still need additional protection or a different winter location.
Understand a cold frame
A low transparent lid shelters plants while allowing light in. It uses little space, but you must reach down to tend the plants and lift or prop the lid safely. Choose a design whose lid can be secured against wind. Keep seedlings from pressing against the glazing and check temperature often on sunny days, even when the outside air is cool.
Understand a greenhouse
A greenhouse provides vertical growing space and room for benches, but it needs a sound base, anchoring and working clearance. Plan the door swing and a route for moving bags and watering equipment. Compare glazing, ventilation and replacement-part availability. Assembly and site preparation can cost as much attention as the frame itself.
Position it for your
real conditions
Avoid placing shelter under heavy shade or where roof runoff floods its base. Consider wind exposure and the changing shade of nearby trees. Local conditions matter more than a universal compass direction. On a balcony or terrace, check building rules and structural suitability before erecting any enclosure.
Ventilation is
part of ownership
Both structures can overheat. Open and close ventilation in response to conditions, not merely the calendar. Automatic openers can help but need checking and do not replace all care. Water according to plant and pot needs, remove decaying leaves and avoid packing plants so tightly that you cannot inspect them.
Choose the smaller
workable option
A cold frame is a sensible starting point if your main need is a modest nursery area. A greenhouse earns its place when you will use the height and access throughout the season. Budget for staging, watering and maintenance, and choose a structure you can safely manage alone or with available help.
