While it's all well and good to study the experts, often you can learn more from the quixotic fumblings of a pretender. And so, I offer you my latest mishap. We recently purchased a vineyard site. Before we made an offer, I was careful to assess its potential: I checked with the state extension viticulturist, who kindly accompanied me to the site to offer his opinions; I verified the wind direction and the aspect (direction of slope); I made sure there was an affordable water source for irrigation (3.5 acre lake); I tested the soil minerality and PH at the university lab; I made sure that there was good airflow and that the vineyard block sites were not subject to cold air ponding; and I checked the drainage maps, which told me that most of my vineyard bloc locations lie in "moderately well drained Winifield loam." Everything looked good, so We made an offer and were fortunate to get our target price.
Now, of all of these qualities the absolute most important characteristic of a vineyard is soil drainage. One might argue that, in freeze- and frost-prone areas like the Midwest, cold air drainage and frost-damage potential are equally important, but I think those come a close second.
It was winter when we bought, and I hadn't run soil percolation tests because of the frozen ground. So when spring came and the pasture thawed and drained off the early-spring mud-soup period that most Missouri country goes through, I dug a few holes, filled them with water, then measured the receding water over a one-hour period. It came out to roughly two inches per hour, which matches the "moderately well drained" description in the state soil maps. I was reassured.
But then I ran a more ambitious test. I dug four 12-inch holes in the area of my first planned vineyard block (2 acres, see the red X on the above map), filled them with water, waited four hours (they were almost totally drained by then) and then filled them again. I waited 24 hours and returned, expecting them to be empty. But they had only drained 7-9 inches. This was not good. After 24 hours, the second filling should be completely drained.
Drainage is important because quickly drained soil means deeper roots, which make for healthy vines for a number of reasons. It also means that vines won't get wet feet, and that vine stress can be encouraged at certain points during the season, benefiting fruit quality.
So I skipped one important step in evaluating a vineyard site. I have an excuse, as the ground was frozen. I didn't want to wait until spring or summer and chance losing the property or having to pay more because that's when the land market tends to pick up. But still, if I had waited, I may have found a better-suited property. This site has a number of advantages: it's high, ridgetop location and it's wind and sun exposure are excellent; it has scenic views; it has good distance from nearby forests to reduce deer pressure and the other challenges of proximity to woodlots. But still, I wish I'd done the drainage tests up front.
All is not lost. I still have one more drainage test to run: the 3-footer. It entails digging a 36-inch hole with a post digger, scrubbing the sides with a nail-studded 2x4, filling it to the brim with water, waiting 72 hours and then checking it again. The water should be gone. This could indicate an overall well-drained soil that just has some compacted layers between 12 and 36 inches. These layers could be ripped with a deep plow or by a dozer with a shank: an easy and inexpensive fix. Or I may repeat all 3 tests in the summer during normal rain conditions (our spring has been wet) and find that the drainage is good enough. But I may eventually find that I need to take more drastic measures, such as installing French drains or drainage tiles under each row. That would increase the planting costs per acre. I still may be able to produce good fruit, but I'd be starting with a much smaller acreage as hiring a drainage contractor would eat up a good deal of my funding.
We've all been cautioned about making assumptions. I trusted the soil maps. They can be a useful tool in site selection, but doing comprehensive drainage testing is essential so you know what you're getting yourself into. It wouldn't hurt to even hire a backhoe and dig soil pits to study before you pull the trigger on a purchase.
Even though its a suspect concept, it's always fun to talk about the "terroir" of your vineyard. The French claim that their terrior, which is the combination of the soil, the history, the culture and climate of a region and its cumulative effects on the grapes, creates some magical formula that makes one region superior to the other. I'm not sure I agree. But I do agree that every region does have a different terrior, or set of characteristics which serve to make a distinct wine. It bucks some of the romance to think that part of your terroir includes contractor-installed drain tiles that artificially change the natural drainage of your soil. It's like when you hear of a big outfit like Mondavi using bulldozers to push over an entire mountain to change its aspect. That sort of knowledge will always leave a different taste in your mouth.
So when you get the idea one evening while enjoying a good glass of wine on the veranda that, "Hey, maybe I should plant a vineyard," without any idea of what you're getting yourself into, realize that you're going to need an entire re-education to make this work. If you're lucky, you'll find that you enjoy the re-education rather than find it tedious. And as always, taking shortcuts could end up costing you in the long run.