I'm gonna be adding a few more plants this year and the only places i have available to do so are in an area with some heavy clay in the ground. I was wondering what the best way is to prepare the ground? I've been told nothing grows well in clay so i assume hops won't either.
Hops will grow under pretty much any soil conditions, but they prefer DEEP well drained soils to grow optimally. Deep, meaning soils that were formed under certain geologic conditions that allow drainage to depth of at least a few feet. This allows the perennial root system to expand downward without the chance of becoming waterlogged. This is crucial being that if the majority of the roots are growing in standing water, their oxygen supply is severely restricted and bad things happen. Stick a dry-cleaning bag over your head with duct tape around your neck and see what happens after a few minutes.
I've been battling the same problem for . . . well, as long as I've been growing them which began back in the late 80's. I've excavated the clay to a depth of about 3 feet and backfilled with a blend of native soil and compost. Then I mounded with the same soil mix to create another foot or foot-and-a-half raised bed situation. In years when we have moderate rainfall, things are great. But, in years when we have excessive rainfall, I feel bad about myself being that water will take the path of least resistance. This leads to what is known as the 'teacup effect'. Sure, the water will drain away from the surface of the mound, but where does it go? It fills up the area that I filled with the 'nice' soil and now the roots are essentially submerged.
You know, we can scratch our heads, figure out how to set up drip irrigation, build elaborate trellis systems, calculate nutrient uptake charts, add supplemental lighting, let loose the lady bugs etc., etc., etc.. But at the end of the day, if you don't have ideal soil conditions, no matter what you've done to try to grow a great crop of hops, it's all for naught. My suggestion would be to do your best and don't expect 2-3 pounds per plant. If you get that kind of harvest and are happy with it, Right On! If you don't get what you were expecting and fret about 'this' and 'that' - take a few deep breaths and pour yourself a beer. If that doesn't work, pack up and move to either the Willamette or Yakima Valleys and set up shop. Even if your hops don't grow after you've moved, there's plenty of good ale out in those parts! Just an observation - and remember to 'B-Hoppy'!!