Can I grow a garden where I'm located?

In my experiences if I wanted to grow some veggies I grew them regardless of what others said. 1 year I had people telling me it'll be too hot to grow cucumbers because we weren't getting any rain. Well I proved them all wrong, I had tons of cucumbers and they had none. I planted mine in an area that got sunlight about 70% of the time and shaded about 30% of the time just to give them time to cool down slowly before sundown so they didn't get any shock in temp changes and I watered them twice as much as what I normally would have. Mine grew and kept on growing all season and they ranged from 9-16 inches. If my memory serves correct it was 2 or 3 years ago and it was one of our hottest, driest summers ever.
Another year I was told none of my onions would grow because I planted them 3 weeks earlier then what the so called experts that they follow gave as a good start date for veggie planting. Well by the time they started planting thier set of onions I was almost ready to pick and replace going onto my 2nd batch of onions(green onions not cooking onions because cooking onions need alot more time to get bigger). Near the end of the season I had picked and replanted 4 or 5 times, I'm pretty sure it was 5 but don't quote me on that...hahahaha.
That same year I was told my sugar snap peas wouldn't grow for the same reason(planting them too early). Mine grew like crazy, and it was so crazy the plants all grew over 8 feet tall which I think was due to the extra few weeks in the ground giving them a huge head start over everyone following the experts opinions. I had originally built a make shift climbing fence like thing with wood and heavy yarn about 6 feet tall for the pea vines to climb(which looked awesome) and I had to keep adding to it with whatever I could use to support these crazy growing pea vines. I wish I had pictures to show you because it looked so ametuer (which really I am) that it was hilarious, even I fell down laughing at it but in the end it served it's purpose. I had the original make shift climbing fence I made then when it got taller I nailed some metal shelving legs(a god awful yellowish colour) to the posts to get more height and ran more yarn from end to end. It looked like something the worst handyman would have done, but hey I worked with what I had because I'm too cheap to spend money if I have something here that can do the job(no matter how stupid it looks). And for those that laughed, I had 10 times the peas they had.
Besides that both onions and peas along with potatoes and alot of other veggies are planted under the ground giving them a bit of protection from the changes in temperature or frost at night that might occur. It's not like your planting tomatoe plants that early or any other veggie thats alot easier to plant using pre-grown plants as apposed to seeds.
I found through trial and error that with any veggie I've planted that starts under the dirt 1st that I can plant them 2-3 weeks earlier and watering them during the afternoon when it's warm once a day.
For my cucumbers I plant them the same way 70/30 sun/shade every year and it works for me. Now depending on your area and the weather this may or may not work. I've lived in Southern Ontario, Western Ontario and right here in the great north, Nothern Ontario and if I wanted to grow it I found a way. One thing I've never tried are those additives for your soil or bagged soil with nutrients or whatever it is they put in it. I've always just turned the same soil and planted and used good old tap water from my hose for watering or rain:)so I'm not sure how those other things work(just in case someone asks).
It basically comes down to trial and error and whether you want to learn exacty when the times are good in your area to plant, where to plant and how often to water based on your weather. It's a learning experience once you think you have it figured out you add a new veggie(s) and it doesn't grow right because what you learned growing everything else works for them but now you need to figure out what works for that new veggie(s). You can get some basic ideas online(like here) or in books but it really comes down to your exact area because alot of what's the so called "written in stone" ways of planting are just guidelines, some work and some don't. I gave up on reading experts advice, trying what they say and still failing , so I decided to learn the hard way and I have done alot better ( I EVEN GREW CORN!!!!!) and everyone said I couldn't because of my location and such a short season. I proved them all wrong and I only used seeds, my garden and water (no other enhancers or additives I grew it all natural).
Remember what I post here is what's worked for me and still works and for some it may or may not work, but at least you can be assured I'm not some expert growing in greehouses, labs or talking to thousands of people to gather my findings, I'm just a regular at home outside gardener who wants to try and help if I can. I've beat my head against the wall so many times trying to grow different veggies until I final got it right so again I hope some of what I post helps.