Site Selection: Topography the First Line of Defense

Soil chemistry is half the story. The other half is shape of land and air/water movement.

Here's the short list I use when evaluating a vineyard block:

1) Aspect & Slope

Aspect: Depends on location, but in general yes, we want slope. How much slope, that is up to some factors. Some locations only present one option like in the above picture in the Mosel River Appellation in Germany. Some places need a southerly slope to ripen specific cultivars. For my region, Missouri, USA, East to East-Northeast to even North keeps mornings bright and afternoons moderated which is ideal for acid retention and thin-skinned varieties. The sun hits the slope and the exposed vines at sunrise, starting the warming process, if we are in that 28–32-degree F frost danger range this can be a crop saver if it is a late Spring frost or Early Fall front.

Slope: 5–12% seems to be a sweet spot that promotes drainage and cold-air shedding. Steeper slope could introduce erosion risks depending on soil type.

2) Elevation & Cold-Air Drainage

Elevation: The best place to put your beautiful winery overlooking the vineyard is not at the top of the hill. I am immediately judging wineries and vineyards if I pull up or walk out on a beautiful terrace and one of the best parts of their Grand Cru potential space is occupied for drinking wine instead of growing wine. Put that beautiful terrace at the bottom of the slope where frost pools and water could saturate. With elevation comes temperature variance. There are many facts that can be pointed toward. Like for every 1,000 ft of elevation temperature drops 3.5 degrees or for every 1,000 ft of elevation UV radiation increases 6–10%. We could cite lower fungal and disease pressure, larger diurnal shifts and the potential for lower frost risk. If we give cold air a clean escape path to a lower basin, we can avoid frost risk in all but the worst-case scenarios.

Cold Air Drainage: Where frost is common, keep the lowest 25–30 ft unplanted or in grass to act as a cold-air channel. Build your terrace here (allow a path for cold air to drain away) instead of the top of the hill (burrow your facility into the hill for an even more free trajectory for cold air like at Rhys or Bella Vineyards in Sonoma County, CA). If you have your row orientation perpendicular to the slope, make sure to build in breaks in the trellising and pay close attention to terracing so that it does not trap cold air on its flow down the slope.

3) Row Orientation

There are obviously many directions one could choose to plant. For example, Bella Vineyards' oldest Lilly Hill Estate block with centennial Zin vines seems to have been planted by a drunk man struggling to walk uphill. East/Northeast aspect, beautiful wine, beautiful vineyard with the winery and reception all built at the bottom of and into the hillside. Which, the drunken vine placement before World War 2 aside, screams serious focus on terroir and getting the best out of their site.

• North to South: balances sun on both sides of the vines. However, the vineyard is affected by the aspect and degree of slope. For example, if the slope is 15 degrees and the aspect is eastern facing there will be less sun to be had in the evening in the fruiting zone and immediate frost reduction benefits in the breaking of morning and thereafter.
• NE–SW can moderate heat spikes from steady afternoon sun. Can be good for wind from the West and works well for soft sloping NE aspect vineyards to help preserve acidity. This is most likely not the right orientation for most Midwest vineyards as our prevailing wind is typically from the SW in the growing season.

In windy sites, align rows to reduce wind tunneling on canopies, do not run them parallel or perpendicular but at some form of angle from 20–60% of prevailing wind. So, if most of your wind is coming from the Southwest in the Spring and Summer then shifting from the Northwest in Fall through winter a N-S orientation is great.

4) Water & Erosion Architecture

Water management must be factored in when establishing a vineyard, especially in climates with high-volume rainfall events, clay influence, or perched water risks (places like Missouri, Illinois, and many places East and South). You can't control storms, but you can work to control how water enters, moves through, and exits the vineyard. Good design along with taking advantage of slope and aspect can mitigate the convective storms we have in America and even help with stratiform rain much of the rest of the world experiences.

• Vineyards could install subsurface drains or French drains where standing water is likely. When we go back and consider CEC and soil make-up from our previous posts it is possible that water can move through the soil without relying on slope like in situations of sand and loess. But, if we have a low slope and clay, considering mitigation techniques like drainage could go a long way to creating a successful vineyard. The whole goal is to keep or get excess water out of the root zone without accelerating erosion. Which would be a big concern with sandy and loess soils and convective rain events.
• Other mitigation techniques include the use of gravel/grassed alleys/cover crops. Using contour plantings following perpendicular to the slope to distribute runoff evenly and from blowing through rows in specific spots. Some people place check berms or swales throughout the block to slow storm pulses. I am a bit more wary about berms as I want to avoid anything that could slow the flow of cold air down the slope and out of the vineyard with our continental climate.

Designing for climate resilience (without gadgets)

You can engineer a surprising amount of resilience with layout before purchasing technology to mitigate natural competition. This way technology can be implemented if proper planning like the above is found to not meet the needs of the vineyard. Here are a few other tactics matched up with common challenges:

• Late frost: Favor higher benches, keep cold-air drains open; delay pruning on riskier zones to shift budbreak.
• Heat spikes: Choose eastern aspects, maintain vertical shoot position with light shade; avoid excess K.
• Drought: Build organic matter, deep roots (great CEC, Ca:Mg), possibly mulch or gravel under-row, and drip with moisture sensors. (Careful with mulch and gravel in colder climates.)
• Deluge: High infiltration via structure; permanent covers; quick-drain outlets. Plant vineyards on soil that keeps nutrients available while also offering rapid drainage, think loess over fractured limestone.
• Hail/wind: Select trellis hardware rated for gusts, maintain windward hedges and make sure to get your row orientation correct. Some vineyards maintain hail nets for parts of the season if hail is particularly prevalent. We want there to be air movement, especially in humid environments to allow quick drying, but we do not want nonstop gusty winds or we will have to take other preventative measures like in the Rhône River Valley, France.