Your weather is very different than where hazelnuts/filberts are grown in the US. Here Oregon is the main place and its cool year-round there. I don't know how heat tolerant they are but in my zone 7 climate they do fine in full sun. On the other hand you may be better with the plants in a bit of shade in your very hot climate.

The plants are often grown as bushes here, they are not grafted so you can let shoots come up from the ground. I have my plants about 1.5m apart to form a hedge row. I have not noticed any special requirements on fertilizers/watering compared to other trees. They also don't need any spraying for me. The main problem is squirrels, they will take all the nuts. I have had a caterpillar attack the leaves, but after awhile some wasps find out and start eating the caterpillars so I don't have to spray. Filbert blight is a major disease here; I don't know if it has made it to where you are or not but if so it can be a huge problem. I am growing blight immune varieties.

Scott

Willamette Valley where most of the Oregon hazel nuts are grown is hardiness zone 8 or 9. 15 to 25 of 90+ degree days per year, 2 or 3 of those 100+ degrees, on average.

I'm back with an update almost a year later on my hazelnut experiment in South Africa. Only two survivors made it through winter dormancy and both were the Selvatico variety.

I found a cherry tree specialist who happened to sell one type of hazel they simply know as "green hazelnut". It hasn't produced nuts in all ten years they've been selling it, which isn't surprising as they have one type. I bought some as potential cross pollinators for my surviving two Selvaticos. They were bare roots, shipped in winter. 80% survival in our dry summer. Below is one of them with the beginnings of a male catkin, in the middle of our summer. Weird!

I recently found a couple of farmers who are pioneering truffle culture here. Hazels are amongst their host trees. They are seed grown, unnamed varieties almost like wild filberts & hazels. I've ordered some for fun, additional cross pollination partners & a potential double crop in 4-5 years.

I am looking up info on the pollination requirement of wild or seed grown hazels. Not much info is available online. I'd be interested in your experiences if you have observed some growing freely in hedgerows (UK) or forests in Oregon.