Answer: Pandorea jasminoides is a tropical plant and needs ample light, warm temperatures, and rich soil to bloom well. It may be that your indoor light is not quite bright enough and your outdoor summer season is not quite long enough so the plant never gains enough strength to bloom.
It is normally a summer bloomer, so you might try a hard pruning back in the winter time, followed by giving it as much light as you can. Fertilize spring through fall with a water soluble fertilizer for flowering plants (such as 5-10-5 plus minors or similar proportions) per the label directions.
For summer, set it outdoors in full sun and be sure to keep it well watered and well fed. If you have not repotted it, you might try repotting into a slightly larger pot with fresh potting mix.
In the spring, gradually acclimate it to being outside by placing it in increasing amounts of morning sun to avoid shocking it when you move it outside full time. You might try setting it out on mild days and bringing it inside at night in order to get it outside in the real sunlight as early as possible without exposing it to cold temperatures. This might help to extend your growing season and thus also the blooming period.
The other option would be to keep it in a heated greenhouse or conservatory every winter so that its growth slows less during the shortened days of winter. I hope this helps.
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