I'm a home-brewer living in zone 9 and I would like to grow my own hops. I've found a few varieties which list 9 as their maximum planting zone, but most of my favorites recommend no higher than 8.
I know that I need to start my seeds in a refrigerator, and I'm planning to put in a raised bed in a tree-shaded area to cut down on direct scorch from our sun.
What techniques can I use to grow plants in warmer than recommended climates?
Plant them behind the north face of a fence, shed or your home. Although the USDA zones are generally accurate, there are micro-zones all over the place that can be as much as one or even two whole zones warmer or colder.
You may not get as deep a cold as actually being a full zone north, but the average winter temp of the north face of your house and it's shadow will be measurably colder than the south face. Low spots in the shade will collect cooler air as well, so if you have a natural trench or valley on the north side of your house, you will get it even cooler.
In Iowa, I lived in zone 5, however I lived on the south face of the river valley (meaning the river was north of me and the sun was mostly uphill from me). My Microclimate was zone 4, and arguably zone 3 depending on where I measured temps on my land in the winter. Although the official temps in the area were as low as -28 for about 6 weeks, there were days I measured -40 degrees.
Escoce's advice is great. I'll just add that hops produce best if they have a chill period of 30-90 days. If you find that they aren't producing well even after planing on the north side of your fence, you could try banking ice around the base of the plant daily for a month. This is a trick that can successfully trick a lilac into blooming in zone 10 and while I can't guarantee it, it may just work for hops as well.
