Understanding Rootstocks: What the Numbers Actually Mean

Almost every wine grape planted commercially is a grafted vine: a Vitis vinifera scion on the roots of an American species or hybrid, because those roots survive phylloxera and vinifera roots do not. The rootstock is chosen once, lives for thirty years or more, and quietly sets how the vine handles your soil's lime, your rainfall, and your fertility.

This page does not tell you what to plant, and you should be wary of anything that does. Rootstock choice depends on soil chemistry nobody has measured from a website, a water table you cannot see, the scion's own vigour, your rainfall, your training system, and what your nursery can actually supply. What follows is what these rootstocks are documented to do, with the disagreements named. The decision is yours and your agronomist's.

Active lime is not total lime

The single most common and most expensive confusion.

Active lime (calcaire actif) is the fraction of soil carbonate fine enough to go into solution and interfere with the vine's iron uptake. It is what causes lime-induced chlorosis — the yellowing between leaf veins that stunts a vine and, on a badly matched rootstock, eventually kills it.

Total carbonate is all the chalk in the sample, however coarse.

They are different measurements and they diverge wildly: a soil can be 40% total carbonate and only 8% active lime. Every figure in the table below is active lime. Ask your laboratory for that specifically. Comparing a total-carbonate result against these numbers will point you at the wrong rootstock while looking perfectly rigorous.

The comparison

These numbers are indicative, not thresholds. Published limits for the same rootstock differ by several points between French, Italian and Australian sources, because they come from different trial soils, different scions, and different definitions of failure. Treat them as a shortlist tool and a conversation starter, not a pass mark.

Vigour is relative. A high-vigour rootstock on thin dry ground may build a smaller vine than a low-vigour one on deep fertile loam. These ratings compare rootstocks with each other, nothing more.

The families, and why parentage predicts behaviour

Most of the table follows from three American species and how they combine.

• V. riparia — riverbank grape. Low vigour, advances ripening, wants moisture, poor lime tolerance. Its descendants inherit all four traits.
• V. rupestris — rock grape. Deeper rooting, more drought tolerance, still low lime tolerance.
• V. berlandieri — the limestone species from Texas. This is where lime tolerance comes from. Difficult to root from cuttings on its own, so it is almost always crossed.

Which gives the rule of thumb that explains most of the table: if a rootstock has no berlandieri in it, it will not handle chalk. riparia × rupestris crosses — 3309C, 101-14, Schwarzmann — top out around 10–12% active lime no matter what else recommends them. The high-lime rootstocks are berlandieri crosses, and the extreme ones (41B, Fercal) had to reach for a vinifera parent or a complex pedigree to get there.

Each rootstock

Riparia Gloire de Montpellier (also written Riparia Gloire, Gloire de Montpellier)

Vitis riparia (pure species selection) · vigour low · active lime 5–8% · drought poor · wet soil moderate

Advances ripening and shortens the cycle, which is why it persists in cool regions despite disliking dry soils. Shallow rooting, so it wants a soil that holds water without waterlogging.

101-14 Millardet et de Grasset (also written 101-14, 101-14 Mgt)

V. riparia × V. rupestris · vigour low–moderate · active lime 8–11% · drought low · wet soil good

Copes with damp, heavier ground better than most low-vigour stocks and brings harvest forward slightly. Its low lime tolerance is the constraint that decides most sites.

3309 Couderc (also written 3309C, 3309)

V. riparia (tomentose) × V. rupestris (Martin) · vigour moderate · active lime 10–12% · drought moderate · wet soil moderate

Long-established and widely planted on deep, well-drained, LOW-LIME soils. Its riparia × rupestris parentage is the reason for the low lime ceiling — this is not a chalk rootstock, and planting it on chalk is a classic and expensive mistake.

Schwarzmann

V. riparia × V. rupestris · vigour moderate · active lime 8–12% · drought low · wet soil good

Behaves broadly like the other riparia × rupestris stocks, with useful nematode resistance reported in several regions.

SO4 (Selection Oppenheim 4) (also written SO4, Selection Oppenheim No. 4)

V. berlandieri × V. riparia · vigour moderate–high · active lime 17–18% · drought moderate · wet soil good

One of the most widely planted rootstocks in northern Europe. Tolerates moderately calcareous ground and heavier soils. Widely reported to aggravate MAGNESIUM deficiency in the scion, which is worth planning petiole analysis around rather than discovering at veraison.

Kober 5BB (also written 5BB, Kober 5 BB)

V. berlandieri × V. riparia · vigour high · active lime 18–20% · drought moderate · wet soil good

Vigorous and tolerant of cool, damp, moderately calcareous soils, which is why it is common in central and eastern Europe. On fertile ground that vigour becomes a canopy-management problem rather than a benefit.

Teleki 5C (also written 5C, 5C Teleki)

V. berlandieri × V. riparia · vigour moderate · active lime 17–20% · drought moderate · wet soil good

Less vigorous than 5BB with a similar soil range — often chosen where 5BB would overgrow. Common in German-speaking regions.

420A Millardet et de Grasset (also written 420A)

V. berlandieri × V. riparia · vigour low · active lime 18–20% · drought low · wet soil moderate

Unusual combination of low vigour with real lime tolerance, which is why it appears on calcareous soils where restraint is wanted. Slow to establish and unforgiving of drought while young.

161-49 Couderc (also written 161-49C, 161-49)

V. berlandieri × V. riparia · vigour moderate · active lime 23–25% · drought moderate · wet soil moderate

Good lime tolerance with moderate vigour. Associated in several regions with sudden vine decline / premature death, which is the reason some growers avoid it despite its otherwise useful profile.

110 Richter (also written 110R)

V. berlandieri (Rességuier n°2) × V. rupestris (Martin) · vigour high · active lime 16–17% · drought high · wet soil low

A standard choice for dry, poor, stony ground in Mediterranean conditions. Deep rooting and genuinely drought-tolerant. Delays maturity, which is an asset in heat and a liability in a cool climate.

140 Ruggeri (also written 140Ru, 140 R)

V. berlandieri (Rességuier n°2) × V. rupestris (du Lot) · vigour very high · active lime 18–20% · drought high · wet soil low

Among the most drought- and lime-tolerant in common use, and correspondingly the most vigorous. On anything but poor dry ground the vigour is very hard to manage.

1103 Paulsen (also written 1103P)

V. berlandieri (Rességuier n°2) × V. rupestris (du Lot) · vigour high · active lime 17–19% · drought high · wet soil moderate

Drought tolerance close to 110R with better tolerance of heavier and somewhat saline soils. Very widely planted in southern Italy.

99 Richter (also written 99R)

V. berlandieri (Las Sorres) × V. rupestris (du Lot) · vigour high · active lime 16–17% · drought good · wet soil low

Similar family to 110R, generally reported as slightly less drought-tolerant and later to mature the crop.

41B Millardet et de Grasset (also written 41B)

V. vinifera (Chasselas) × V. berlandieri · vigour moderate · active lime ~40% · drought good · wet soil low

The classic Champagne chalk rootstock, and the reference point for extreme active lime. The trade-off is in its parentage: a vinifera parent means phylloxera resistance is MODERATE rather than high, which is the whole reason it is not simply used everywhere.

Phylloxera resistance: Moderate — lower than the others here, which is a deliberate trade-off rather than an oversight.

Fercal

Complex: (Berlandieri × Colombard No. 1B) × 31 Richter · vigour moderate–high · active lime ~40% · drought moderate · wet soil moderate

Bred specifically for chlorosis resistance on very calcareous soils, with better phylloxera resistance than 41B. Reported to be sensitive to potassium and magnesium supply, so nutrition wants watching.

Gravesac

161-49 Couderc × 3309 Couderc · vigour moderate · active lime 10–12% · drought moderate · wet soil moderate

Selected in Bordeaux for acidic, gravelly soils where it tolerates low pH and free aluminium better than most. Not a lime rootstock despite one calcareous-tolerant parent.

Ungrafted vines

Own-rooted vinifera is viable only where phylloxera is genuinely absent — some pure sand soils, Chile, parts of Australia, isolated pockets elsewhere. "We have never seen it here" is not the same as absence, and phylloxera arrives once. If you are considering it, that is a question for your local extension service and your regulator, not a website.

What we deliberately have not built

A rootstock recommender. We could join your block's soil data to this table and print an answer, and the answer would look authoritative and occasionally be wrong in a way you would discover in year three. Rootstock selection is regional, contested, and irreversible; making that call for you would be a judgement we are not qualified to make about a site we have not seen.

What we may build is a comparison — filter this table by conditions you name, with the sources shown and the trade-offs visible. That does the legwork without pretending to the expertise.

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Generated from spec/rootstocks.json, so the figures here and anywhere else we use them cannot drift apart. Compiled from the general viticultural literature rather than any nursery's catalogue. Where we could not establish something confidently, it is absent rather than guessed.