How can I shape bougainvilleas on a trellis?

Question

I have a trellis (Cairo Egypt) that I would like my bougainvilleas to completely cover. The trellis is 2 meters in width and 4 meters in height. I planted 4 bougainvilleas each apart by 0.5 meters. However I’m not sure now how it would cover the entire trellis. I want it to be very dense, so I have two options I guess:

• plant more bougainvilleas with more density, so maybe between each two bougainvilleas I already planted I add one more, but I'm not sure if 0.25m between each plant is a safe distance
• or after the bougainvilleas reach out the 4 meters height, I try to twist it to 180 degrees so it continues spreading in the other direction

The idea here is to have a wall of bougainvilleas, completing covering what’s behind it.

Answer 1

Unless you bought the more dwarf forms of Bougainvillea, the spacing you mention is fine - average height and spread is 4-8 metres by 1-1.5 metres, so by tying them in as they grow (they don't cling or twine on their own round supports) you should easily achieve the cover you require with the number of plants you have already. They do better with a minimum of 6 hours sunlight a day - where you are in Egypt, temperatures year round should be fine for them because it seems your coldest temperatures are around 14degC even in January. General guidance on growing these plants here https://www.joyusgarden.com/secrets-bougainvillea/