Greenhouses can still be useful if you pull the right parts. The glass is usually the easiest—just replace broken panes, seal the edges, and clear the vents. The frame, those old steel or aluminum beams, is where the real work starts. Corrosion on the joints and misaligned angles will need careful straightening and welding. Pumping and irrigation systems are the trickiest; the pre‑war electronics are stubborn and often wired backward, so you’ll have to reverse engineer the circuitry, check the pressure regulators, and clean up any clogged valves. If you can get those parts running, the whole structure can breathe again. Just keep the work to yourself, don't let anyone else meddle, and test the system with a full load before calling it finished.