Prince Edward County Terroir

  • By Jamie Drummond
  • 23 Sep 2020
  • 5 MIN
  • Level 101
Made possible by
Prince Edward County Vineyards - Credit : Courtesy of WMAO-VQA-PEC

Topographically Prince Edward County is like a giant limestone pool table gently rising from south-west to north-east, punctuated by small east-west ridges and the occasional outcrop of rugged escarpment.

Underlying everything here is the Trenton plateau, a body of calcium-based or calcareous limestone. This differs greatly from the magnesium-based Dolomite limestone found in Niagara, in that the PEC limestone is much older and friable (read: breaks down and fractures more easily).

Calcareous limestone comes from the Ordovician period and is some 485.4 – 443.4 million years old, considerably older than the Devonian limestone found throughout Burgundy and Champagne which is around 419.2 – 358.9 million years old. It is the oldest limestone in North America, and one of the oldest limestone formations in the world.

The aforementioned friability is key here, as with this combination of rocky clay soils and a limestone substrate that is extremely prone to cracking and fracturing, one finds the perfect balance between water drainage and retention. 

The fractured limestone also provides the stone material that is pushed to the surface during the upwards swelling of soil during freezing conditions otherwise known as frost heave, perpetuating the soil’s inherently rocky nature.

As well as these rocks, west PEC’s reddish brown heavy clay soils have an exceptional moisture retaining capacity. With clay having such a small particle size, and hence a larger surface area between said particles, it is capable of holding 10 thousand times the moisture of sand.

One issue with such heavy clay soils is compaction, as if this clay becomes seriously compacted it can become rock-like and impervious to water; this is referred to as hardpan. This is mitigated by a process known as subsoiling, where the potential hardpan is broken up by the use of a mechanical subsoiler or deep ripper, a long-toothed plough.

The mother of all soil types here is the limestone, but there are some points in the County where it will be overlaid with some old lakeshore creek bed that will provide some sandier and loamier spots.

As one moves south-east of Hiller the soils become sandier, as this is where one will find all the old lake beds, with some soils being pure sand, such as those of Sandbanks Provincial Park and Morrison Point Road. Some of these particular soils look like finely crushed seashells, but somewhere underneath you can be sure that there is beautiful Calcareous limestone formed by millions and millions of years of sedimentation from Lake Ontario.

The free active calcium content in the PEC’s limestone is something that is reflected in the soil pH. These pH levels are quite a bit higher than elsewhere, being from 7 to 8.6. While we are talking small amounts in the overall scheme of things, this does change the way in which the roots uptake nutrients.

For example, magnesium is a nutrient that is more difficult to pick up in high pH soils, so magnesium sulfate (read: Epsom Salts) foliar sprays are commonplace throughout the year, not as a fertiliser but as an augmentation to provide magnesium to the leaves as this is essential for chlorophyll, and hence photosynthesis.

The unique climatic conditions of the County are often overlooked. The region’s proximity to Lake Ontario has a great influence over ripening cycles, overall heat units, and other factors that are important in the maturation of grapes.

The lake influence is at its greatest within 3km of the shore, but when one gets more inland to Closson Road the daytime temperatures get hotter, but the nightimes cooler. This means the inland growing seasons are often more compact as vineyards are more prone to frost. Usually bud break will happen a little earlier there, as will first frost. Pinot and Chardonnay work well all over the County, but there are some varieties that benefit from that little bump of heat units found inland, like Cabernet Franc, a grape that has only recently found a home here.

As well as suppressing disease pressure by moderating temperatures and drying out the vineyards (a real benefit with delicate thin-skinned varieties such as Pinot Noir), onshore winds from Lake Ontario bring cooler nights which also help to preserve acidity and lower the pH of the final wines. 

This heightened spine of acidity and lower pH give the wines of PEC a real mouthwateringly crisp acidity and saline character that is unique to the region. This naturally fresh acidity brings structure, helping with the longevity and age worthiness of the wines.

Prince Edward County Vineyards - Credit : Courtesy of WMAO-VQA-PEC