Explained: Grapevine Rootstocks

Following on from our Clones guide, the next in our Explained series looks at rootstocks. In the UK, where soils can range from pure white chalk to heavy, waterlogged clay, what happens underground is just as important as what happens above ground. We'll answer what rootstocks are, why we need them and how to choose one.

Why Do We Need Rootstocks?

You can thank a tiny, devastating aphid called Phylloxera for why we use rootstocks.

In the late 19th century, this pest nearly wiped out the European wine industry. European vines (Vitis vinifera) have no natural defense against it, but American vine species do. By grafting a European top (the scion) onto an American root system (the rootstock), we get the best of both worlds: high-quality grapes and a vine that won’t die from root pests.

An adult Grape Phylloxera

Beyond survival, rootstocks act as an engine for the vine. They control how much water and nutrients the vine takes up, which determines how vigorous or leafy the vine becomes and how early the grapes ripen.

Choosing a Rootstock in Britain

Choosing a rootstock in Britain is usually a battle against high lime content (which causes chlorosis/yellowing leaves) and cold, wet feet. We've listed a few of the most popular that we provide below:

SO4 / Sélection Oppenheim 4

This is the most common rootstock we provide and is almost certainly the most planted one in the UK. SO4 has a moderate to high vigor and is very resilient to a wide range of soils found in Britain. It induces early ripening which better suits our shorter growing season and summers here.

41B / Millardet et de Grasset

41B is perfect for chalky soils which is why it's often planted in the downs of Hampshire or Sussex. It has an incredible tolerance for high limestone (calcium carbonate). In high pH soils where other vines would turn yellow and fail to photosynthesize, 41B avoids this making it a great choice for Champagne-style chalk sites.

Binova

A variation of SO4, Binova is frequently used in cool-climate viticulture. Whilst it is similar to SO4, it is cited as having slightly better resistance to a colder British June, ensuring that flowers turn into grapes.

Fercal

Fercal is best for difficult for high-lime soils. It was specifically bred to be even more lime-tolerant than 41B and is highly vigorous. In poorer soils where a vine might struggle to grow a large enough canopy to ripen the fruit, Fercal helps provide more energy.

Gravesac

As the name suggests, derived from Gravel, this rootstock was designed for acidic, stony soils. In areas of Britain with more sandy or gravelly soils, Gravesac is more suitable, it handles low pH much better than SO4 or 41B.

Newer Rootstocks

Whilst these are the most popular rootstocks, we are keeping a close eye on the development of more modern rootstocks that could be even more suitable for the UK and especially here in the north of England.

• The M-Series (e.g., M1, M3): Developed by the University of Milan in Italy, these are being trialed for their superior drought tolerance and efficiency in nutrient uptake which is becoming increasingly important as British summers become hotter and drier.

• SW (Star Vine) Series: Some newer rootstocks are being tested specifically for their ability to resist a wider range of soil-borne viruses, which can be a silent killer of vine productivity over 20+ years.

If you need advice choosing a rootstock, or for any not mentioned here, please contact The Vinehouse UK directly at info@thevinehouse.co.uk.