It's a common and sensible worry, especially for a plant-filled conservatory or windowsill. The short answer: most houseplants are absolutely fine behind solar or UV window film, because film mainly cuts the heat and UV — not the visible light plants rely on most for photosynthesis.
What plants actually need
Plants photosynthesise mostly with visible light, which solar and UV films transmit in large part. They don't need UV (which film blocks) and they certainly don't need the excess heat that film reduces — in fact, many houseplants are damaged by the scorching heat and intense direct sun that an untreated sunny window produces.
Film can help plants
By taking the edge off fierce direct sun and heat, film can reduce leaf scorch and stop a conservatory cooking your plants on hot days, while still giving them plenty of light. For most collections it's neutral to beneficial.
The exceptions
Very high-light specialists (some cacti, succulents and fruiting plants) that want maximum intensity may notice a heavier, darker film. If you grow those, mention it on the survey and we'll recommend a lighter, high-clarity film for that window.
The bottom line
Most houseplants are fine — even happier — behind solar/UV film, which keeps the visible light they use while removing damaging heat and UV. Tell us about any high-light plants and we'll spec accordingly. Book a survey to discuss.
Thinking about window film? We offer a site survey anywhere in Scotland, with most quotes returned within 24 hours.