Saturday, May 5, 2012

Close Planting of Grapevines - Q&A

Hi DJ's,

What is your take on close planting? Under what conditions would you consider it, especially in relation to Cabernet and Merlot?

Thanks,

Ryan J


Thanks Ryan,

Great question. We will try to answer this as best we can. Planting density sparks a great deal of debate, especially with some South Australian nursery sources, or the international high flying Michel Rolland claiming that it improves wine quality.

Where does this thinking come from?

Background.


There is no single reason for high planting density - simply planting closely does not ensure greater concentration of fruit flavours, nor does it ensure the greater root-competition induced improvement of flavours. Conversely, we are not aware of any research that shows planting widely degrades the quality of the resulting wine. It all depends on the site and the vineyard management.

High density planting comes from having narrow rows and close vine spacing.

Vineyard in Bourgogne's Côte d'Or départment.
In Europe there is both high density and low density planting.

The Bourgogne currently plants on a basis of 10,000 vines a hectare (1m x 1m) for Premier Cru and Grand Cru - though there are as many variations on this theme as there are vineyard owners, with some planting "out" to 1.3m x 1m. and some "in" to 1m x 90cm. These vineyards are of course planted to the variety Pinot Noir.

In the Bordeaux regional AOC's, the traditional home of Cabernet Sauvignon and Merlot planting densities range from 4,000 to 10,000 vines per hectare.

The trellis’ in some of Bordeaux are much like that in McLaren Vale – wider spacing’s, and high cordon height – particularly around Sauveterre.
High density in Bordeaux with 1.2m row width.

Sources reporting on pre-phylloxera Bordeaux vineyards had extremely dense plantings - up to 28,000 vines a hectare - but we don't know whether these densities produced better wines. The best source is considered to be the early 20th Century wine scholar George Saintsbury and he could not differentiate between pre and post phylloxera wines.

Balancing this are vineyards in Spain where they  entirely consist of goblet pruned, free-standing vines - all quite old and sufficiently widely spaced that tractors can pass all four ways through the vineyard, for cultivation purposes.

Spanish low density vineyards in Rioja, like those pictured, are considered to be some of the most valuable in the world.
Tempranillo in Rioja Alavesa.

McLaren Vale vineyard c.1970.
Tio further this many of the original McLaren Vale vineyards were similarly planted as low density vineyards. Some of these are still in production and make excellent quality wine.

 

Climate plays a part.


Conditions in south eastern Australia and high rainfall parts of western Europe are very different. Also in the New World vineyards we have the flexibility, in most years, to irrigate - and this alone is a massive change to the root environment and to productivity compared to the 'Old World' where irrigation is limited.


European experience is not to be sneered at - but this is not directly applicable to Australian sites. It suits the cool-climate and shallow soils of say Bourgogne - but this does not necessarily apply to the deep, rich silt loams of say Langhorne Creek - or the volcanic soils around Stellenbosch in South Africa

Close planting at 0.8 m vine spacing with unilateral training.

Narrow row width = high density.

Spacing of the vineyard rows is more straightforward.

If each row of vines represents the machines in your "factory" then the greater number of factories you can have, the greater the production from the vineyard. Therefore the greater the number of rows, the greater the potential yield.

The vine is acting on intercepted sunlight so it is important to minimise shading of adjacent rows. Smart and Robinson (Sunlight into Wine), came up with the coefficient of canopy height plus 10% as the row width (1.1H).  Just note that you can't go too close together as it makes tractor operations difficult. In practice rows narrower than 2.6 meters begin to limit tractor operations.

A McLaren Vale vineyard with 2.4m vine row width. Note the vineyard has difficulty with routine operations like fertiliser application and weed control because the rows are too narrow for contractor machinery.

Should you plant Cabernet and Merlot in high density?


To directly answer the question, Cabernet Sauvignon and Merlot can be successfully grown at low to high densities, they are in many cases including in Bordeaux.

Climate, and vine vigour are the factors to consider.

If you have a low vigour, dry site then close planting may not be the right way to go. We would look to planting these closely if the climate and soils resembled European conditions - which they can do in the Adelaide Hills, an in some other areas.

Whichever way you go what we would aim to achieve, in all cases, is a "balanced vine". We have a strongly-formed opinion that overly stressed vines make stressed wines - and a balanced an healthy vine will make good wines - almost regardless of other factors.

Narrowing vine rows can be a good option of increasing vine density, but tractors are going to limit how narrow you can go.

3 comments:

Ashley said...

Close planting reduces the amount of time the soil surface is exposed to the sun, hence less water loss during irrigation.

Chris said...

My answer:

Vine spacing is one of those things that you should really try to get right when you're planning the vineyard. It's one of the reasons why detailed soil surveys are done before vineyards (incorporating variety, trellis, rootstock etc.) are designed. Get the spacing too tight, and the vines will outgrow the volume of space available to them. Get it too sparse, and the vines may not be able to take advantage of the volume allocated to them, leading to unused cropping potential.

James Tilbrook said...

We have 20 rows of close planted Pinot Noir in the Adelaide Hills. The planting density is 1.25 x 0.8, giving a theoretical 10,000 vines per hectare. Next to this on the same aspect is 20 rows planted at 2.5 x 0.8 = 5000 vines per hectare. Both were planted in 1999. RAW is about 50mm with a sandy clay loam over red clay. Our experience is that we need specialist equipment to manage the close planted, whereas the normal spacing any old vineyard tractor will do. In fact in the close planted we use a ride on lawnmower towing a 200L spray tank and a Solo two stroke air blast sprayer. The main problem with this is potential exposure to pesticides even though I wear a spray hood, gas mask and protective clothing. I'd rather be in a spray cab! Comparing the two blocks one can immediately see that the vine trunks in the close planted are thinner than in the normal block. One can therefore deduce that close planting does control the overall vigour. The soil moisture at depth is drier in the close planted although the grass does tend to be greener due to the shading effect that Ashley mentioned. I'd suggest that there is a resulting higher humidity in the canopy with less wind penetration, so in areas where it is more vigorous one needs to keep a close eye out for Powdery and Downy. We have a winery and use all the fruit from both blocks. We have two other blocks but these two blocks are our best. Comparing the fruit quality one can say they are similar but the close planted can have more depth and intensity. Why? I think the main reason is not really the planting density but because when we talk about an optimum yield of 5 tonnes per hectare (2 tonnes per acre) this is actually meaningless. What we should be talking about is a balanced vine and kg per vine. Both blocks produce balanced vines but in the close planted 5 tonnes per hectare means 0.5 kg per vine, whereas in the normal spacing it means 1 kg per vine. So the close planted vines need alot more bunch thinning! The result though is more concentrated fruit. Is it worth it? Considering you have twice the set up cost, twice the pruning cost, and alot more hassle machinery wise, probably not!! But from a marketing perspective how many other wineries can say "close planted" on their labels and really mean it? Bannockburn Serre at $100 a bottle is one example, there's not many others......so if you're prepared to put up with a helluva lot more cost and hassle then it might just be worth it!