I'm at 8500 ft. & this year is my second attempt at raised gardens. Learned a lot last year and had little yield. This year I got good soil/ manure for the beds and built a PVC and plastic sheeting cover with a strip of shade cloth on the top for ventilation. I think I cooked it last year without any ventilation. It gets hot under the plastic! So far I've got good looking zucchini, squash, beat & tomato plants. Will be awhile before I get anything though.
Did a second lettuce box with just shade cloth over the top, no plastic. Planted 3 kinds of lettuce, spinach, radishes & a pumpkin just for the heck of it. Been harvesting lettuce & spinach like crazy, probably planted too much! Getting radishes too. Not to sure about the pumpkin although it's a big healthy looking plant. Really hoping the rest of the stuff provides a good harvest too!