When do you need to bring your plants indoors for the winter?

Short answer: it depends on the plant, but generally when the nighttime temps start dipping below 10ºC/50ºF or so is a good benchmark.

Longer answer: Check out our care guides for each plant that you have outside -- one of the entries on the beginning table is how hardy they are!

Most houseplants are tropical plants, which means that they need to come inside over winter or they'll sustain cold damage, and eventually die due to cold. For most common houseplants, the generally-accepted "safe" cutoff is about 10ºC/50ºF -- for the YQG/Windsor area, nighttime temps start hitting around there mid-September or so.

A few caveats to that, though.

First: Some houseplants will start showing signs of cold damage below about 15ºC/60ºF instead -- expect thinner leaves to likely mean a higher cold threshold (though this isn't always the case).

Some houseplants -- including, surprisingly, many succulents -- can withstand much colder temperatures! Some can even withstand brief periods of freezing temps. They generally don't fare well at these temps, but they'll survive.

As well -- all houseplants can survive brief periods at or just below these temps. If you leave your plants outside overnight when it dips to 8ºC, your plants will very likely be fine! Some plant owners are much riskier than others, and will only take their plants inside when the nighttime temps are consistently below these thresholds. Others (like me!) will take them in as soon as the nighttime temps reach that threshold once -- just to be safe. 

So, the long answer: it depends entirely on how risky you want to be! Are the last few days of bright outdoor light worth the risk of cold damage, or would you rather them get as much light as possible for as long as possible? There's no wrong answer here -- except for leaving them out in so much cold that they die!