Q.Hibiscus has lost most of its leaves
We over wintered our hibiscus indoors because we live in zone 3 and it’s very cold here for several months. The plant survived and was flowering well in April. However it’s lost most of its leaves and although still very much alive and flowering nicely, the leaves are few and mostly at the end of the branches close to where it is flowering. Is there anything I can do? We have watered it well and it is now back outside in the warm weather.

Here is a couple links with more information.
Your standard has a nice shape and appears to be leafing out.
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm