6 Rootstock Compatibility Charts That Prevent Graft Failure

There’s nothing more frustrating than watching a perfectly executed graft fail. You did everything right—the clean cuts, the tight wrap, the sealed wound—but weeks later, the scion is withered and dead. The most common culprit isn’t your technique; it’s a silent, invisible mismatch between your scion and your rootstock.

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Why Rootstock Compatibility Is Crucial for Success

Choosing the right rootstock is about more than just keeping a graft alive for a season. It’s the foundation for the entire life of your tree. A compatible union ensures the vascular systems—the xylem and phloem—line up perfectly, allowing water and nutrients to flow unimpeded.

An incompatible graft might look successful at first. It might even push out a few leaves. But over time, the poor connection strangles the tree, leading to stunted growth, weak limbs, and a premature death a few years down the road. This is called delayed incompatibility, and it’s a massive waste of time and resources.

Think of rootstock as the engine and scion as the chassis of a car. A good match results in a tree that is not only productive but also resilient. The right rootstock can provide dwarfing for a small space, disease resistance for a challenging climate, or drought tolerance for poor soil—benefits you’ll never get if the basic connection fails.

How to Read and Interpret Compatibility Charts

Compatibility charts look intimidating, but they are simple tools once you understand the language. They are typically set up as a grid, with scion varieties listed on one axis and rootstock options on the other. The cell where they intersect contains a symbol or a letter indicating their level of compatibility.

Common codes you’ll see include:

• C = Compatible. This is a reliable, long-term union.
• I = Incompatible. The graft will likely fail immediately or within the first year.
• D or DI = Delayed Incompatibility. The graft may grow for several years before failing unexpectedly. This is the one to watch out for.
• S = Satisfactory. The union works, but may not be as vigorous or productive as a fully compatible one.
• IS = Interstem needed. Direct grafting is incompatible, but a small piece of a compatible variety can be grafted in between to bridge the gap.

Remember, these charts are guides, not guarantees. Local soil conditions, climate, and even viral load in the scion wood can influence success. Always use a chart as your starting point, not your final word.

Apple Rootstock Chart for Malus Varieties

Apples are arguably the most predictable fruit to graft, thanks to decades of research on the Malling (M) and Malling-Merton (MM) series of rootstocks. Compatibility is less about a simple "yes" or "no" and more about matching the rootstock’s traits to your goals. Almost all apple varieties (Malus domestica) are compatible with each other.

The real decision comes down to size and site conditions. A ‘Honeycrisp’ scion will graft onto any of these, but the result will be dramatically different.

• M.9 or M.26: Creates a dwarf tree (8-12 feet). Requires permanent staking and consistent watering but fruits very early.
• M.7 or G.935: Produces a semi-dwarf tree (12-16 feet). A good compromise of size and sturdiness, often freestanding.
• MM.111 or B.118: Grows a semi-standard tree (18-22 feet). Excellent for poorer soils or areas with drought, as it has a vigorous root system.

The key takeaway is that with apples, your "chart" is less about graft survival and more about a strategic choice. Choosing a rootstock for an apple is choosing the ultimate size and resilience of your future tree. Don’t just pick one at random; match it to your space and soil.

Pear and Quince Rootstock Compatibility Guide

Pears present a more complex puzzle. While European pears (Pyrus communis) can be grafted onto standard pear seedling rootstock like ‘Bartlett’ or ‘Winter Nelis’, the real magic for a small farm comes from using quince (Cydonia oblonga). Quince rootstock creates a smaller, more manageable tree that fruits years earlier.

The problem is that not all pears play nicely with quince. This is where a chart becomes essential. A classic example is the ‘Bartlett’ pear, which suffers from delayed incompatibility on most quince rootstocks. The graft union slowly fails, and the tree snaps off at the base after a few years of good growth.

To solve this, growers use an interstem. A compatible variety like ‘Old Home’ or ‘Hardy’ is first grafted onto the quince rootstock. The following year, the ‘Bartlett’ is grafted onto the ‘Old Home’ interstem. This creates a stable, long-lasting, dwarfed tree. Always check a pear/quince chart before grafting; assuming compatibility can lead to a tree that self-destructs.

Stone Fruit Chart: Peaches, Plums, and Apricots

Welcome to the wild west of grafting. Stone fruits (genus Prunus) have a dizzying array of cross-compatibility, and a chart is absolutely non-negotiable. While some general rules apply, the exceptions will sink your project.

Plums are the most versatile players in the stone fruit family. ‘Myrobalan’ plum rootstock, for instance, is often used as a rootstock for other plums, apricots, and even some peaches. However, peach on plum rootstock can be a gamble, often resulting in a weak union or short-lived tree. Apricots are notoriously fussy and generally do best on apricot seedling rootstock.

Here’s a simplified look at the complexity:

• Peach/Nectarine Scion: Best on peach rootstock (‘Lovell’, ‘Bailey’). Sometimes works on ‘Myrobalan 29C’ (plum) or ‘St. Julien A’ (plum) in specific situations.
• Apricot Scion: Best on apricot rootstock. Can work on peach rootstock for better drainage or plum for heavier soils, but compatibility is highly variety-dependent.
• Plum Scion: Generally compatible with other plum rootstocks. European plums do well on ‘Myrobalan’, while Japanese plums have other specific needs.

The lesson here is specificity. It’s not enough to know it’s a "plum rootstock"; you need to know if it’s ‘Myrobalan’, ‘Marianna’, or ‘St. Julien’ and check that specific interaction.

Cherry Rootstock: Sweet vs. Sour Compatibility

Cherries have a hard and fast rule that trips up many beginners: sweet cherries (Prunus avium) and sour cherries (Prunus cerasus) are generally not compatible graft partners. Attempting to graft a ‘Bing’ (sweet) onto a sour cherry rootstock will almost always end in failure. The two species are just too different genetically.

Your choice of rootstock, therefore, depends entirely on what kind of cherry you want to grow. For standard, full-sized trees, ‘Mazzard’ (for sweet) and ‘Mahaleb’ (for sour, and some sweets in well-drained soil) have been the go-to for generations. They produce large, hardy, long-lived trees.

For smaller, more manageable trees, the German ‘Gisela’ series has changed the game. These rootstocks offer size control and encourage early fruiting.

• Gisela 5 or 6: Excellent for sweet cherries, creating a dwarf or semi-dwarf tree that is highly productive.
• Gisela 3: A more dwarfing option, requiring permanent support.

When selecting a cherry rootstock, the first question is always "sweet or sour?" Get that wrong, and no amount of careful technique will save the graft.

Citrus Rootstock Options for Diverse Climates

With citrus, compatibility is less about the graft union failing and more about what traits the rootstock gives the tree. Most common citrus varieties (oranges, lemons, limes, grapefruit) will successfully graft onto a wide range of rootstocks. The choice is a strategic one based on your environment.

The rootstock is your defense against local challenges. In Florida, with its sandy soil and nematodes, ‘Swingle’ citrumelo is a popular choice. In California, with heavy clay soils and concerns about Phytophthora root rot, ‘Trifoliate Orange’ or its hybrids are often used.

Here are some common scenarios:

• For Cold Hardiness: ‘Trifoliate Orange’ (Poncirus trifoliata) is the champion. It imparts the most cold tolerance to the scion, making it possible to grow citrus on the edge of their hardiness zones.
• For Poor/Alkaline Soil: ‘Sour Orange’ is famously tolerant of a wide range of soil types, though it has susceptibility to certain diseases.
• For Dwarfing: ‘Flying Dragon’ is a contorted, dwarfing version of Trifoliate Orange, perfect for growing citrus in containers or small spaces.

Your citrus rootstock chart is a map of environmental solutions. You aren’t just choosing a rootstock; you are choosing your tree’s ability to fight off local diseases and thrive in your specific soil.

Nut Tree Grafting: Walnut and Pecan Charts

Grafting nut trees is a different ballgame. The wood is harder, the timing is trickier, and the compatibility is far less forgiving than with fruit trees. For walnuts and pecans, you generally stay within the same species for the best results.

For walnuts, the most common practice is grafting English or Persian walnuts (Juglans regia) onto Black Walnut (Juglans nigra) rootstock. Black Walnut provides a vigorous, disease-resistant root system that is well-adapted to many North American climates. Grafting J. regia onto other J. regia seedlings is also done, but the Black Walnut rootstock offers superior resilience.

Pecans (Carya illinoinensis) are almost exclusively grafted onto pecan seedlings. While there is some cross-compatibility within the hickory genus (Carya), it’s an expert-level pursuit. For the hobby farmer, sticking to pecan-on-pecan is the reliable path. The key with nut trees is that the rootstock is chosen for its rugged, native adaptability, providing a strong foundation for the more specialized, productive scion.

A compatibility chart is more than a simple guide; it’s a strategic plan for the life of your tree. By understanding and using these charts, you move beyond hoping a graft takes and start designing trees that are built to thrive in your specific environment. This knowledge is the true foundation of a successful and productive home orchard.