Apple tree rootstocks: what types are there, which to choose, how to grow and combine them?

The rootstock is a key component in apple tree cultivation, largely determining the tree's health, growth, yield, and adaptation to environmental conditions. Choosing the right rootstock helps gardeners achieve a compact or vigorous tree that is resistant to disease and climate fluctuations.

The history of the emergence of rootstocks

In the past, apple trees were typically grafted onto seedlings, resulting in tall trees with late fruiting and a gradual increase in yield, often with fruit of poor quality. However, moderately tall specimens have been observed, producing higher-quality fruit.

This observation spurred gardeners to search for apple trees suitable for use as rootstocks. Key requirements included high compatibility with cultivated varieties, growth restriction, and the ability to vegetatively propagate.

Key Features:

Large-scale work on rootstock research began in the 19th century, during which various low-growing species and forms were tested and the most promising specimens were selected.
At the beginning of the 20th century, a significant collection of clonal rootstocks was assembled at East Malling Station in England, where they were studied and classified. As a result, the rootstocks were divided into 16 groups, differing in height and other characteristics.
This classification has received international recognition, and today these rootstocks are known as M1-M16. This list has subsequently been expanded.
Later, the rootstocks MM 101-MM 115 were bred, where the double “M” indicates the collaboration between the East Malling Station and the Institute in Merton.
I. V. Michurin also worked on clonal rootstocks, but despite their winter hardiness and dwarfism, they did not become widespread.
In the USSR, the selection of dwarf rootstocks began in the 1940s. In the North Caucasus and Dagestan, clonal rootstocks for southern regions were bred, while in Michurinsk, V. I. Budagovsky developed winter-hardy rootstocks for temperate climates. The result was resistant rootstocks widely used both in Russia and abroad.

What is rootstock and why is it needed?

The rootstock is the lower part of the seedling, including the root system and the part of the trunk onto which the varietal plant (scion) is grafted.

Why is it needed:

provides the plant with nutrition and water supply through the roots;
affects the growth force, size of the tree, and fruiting period;
increases resistance to diseases, pests, frost, drought;
helps to adapt the cultivated plant to unfavorable soil or climate conditions.

The scion, on the contrary, is responsible for the varietal qualities – the taste of the fruit, its shape, and its yield.

What is the difference between a rootstock and a scion?

Rootstock – The lower part of the plant containing the root system. It provides nutrition, resistance to external conditions, and determines growth strength.
Scion - The upper part of the plant that is grafted onto the rootstock. It determines varietal characteristics, including fruit appearance, flavor, size, and yield.

In other words, the rootstock is the base, and the scion is the cultivar. Together, they form a single plant with the desired characteristics.

What types of rootstocks are there and what is the difference between them?

For a deeper understanding of this topic, it's useful to introduce the classification of rootstocks. Each type has its own set of advantages and limitations, which determines its applicability to agricultural enterprises of varying sizes and specializations.

Dwarf

Dwarf trees have a number of characteristics that cause gardeners to disagree about the advisability of growing them. Their advantages include the ability to plant in areas with high groundwater levels, as their root system is shallow.

Apple trees on dwarf rootstocks begin bearing fruit as early as 2-3 years after planting and demonstrate vigorous growth. However, the shallow root system also explains the weaknesses of dwarf trees: they are less resistant to frost, drought, and sudden temperature changes.

The height of trees on dwarf rootstocks rarely exceeds 2.5-3 m, so such plants are well suited for small areas and simplify maintenance.

Advantages of dwarfing rootstocks:

rapid entry into fruiting (2-3 years);

compact size, ease of maintenance and harvesting;

suitable for areas with high groundwater levels;

can be grown in limited space;

well suited for intensive gardens.

Flaws:

poor resistance to frost and drought;

the shallow root system requires regular watering;

may break under the weight of fruit or snow - support is required;

less durable compared to vigorous trees;

demanding in terms of soil quality and care.

Semi-dwarf

Semi-dwarf rootstocks occupy a position between dwarf and vigorous trees. They are characterized by a moderate height, good adaptability, and less demanding care. They establish themselves more quickly in new locations, easily combine with different apple varieties, and are suitable for most climate zones.

Semi-dwarf varieties are moderately frost-resistant, produce high yields, and begin bearing fruit around the third to fourth year. Their root system is more developed than that of dwarf varieties, so they tolerate short-term drought better. However, they do not tolerate excess moisture—stagnant water can lead to root rot.

Semi-dwarf trees are considered the golden mean: they don't take up as much space as vigorous varieties, but they produce consistent yields and are easier to grow than dwarfs.

moderate height and compactness;

good survival rate and compatibility with most varieties;

early fruiting;

high yield;

tolerate drought better than dwarfs;

fewer requirements for soil and care.

average frost resistance – may suffer in harsh winters;

sensitivity to waterlogging and stagnant water;

some rootstocks have poor survival rates;

the life cycle is shorter than that of vigorous trees.

Medium-sized

These rootstocks are similar in size to semi-dwarf varieties, but are more resilient to external conditions and adapt better to climate change. They are easy to grow, have well-developed roots, and provide consistent fruiting, although not as early as dwarf and semi-dwarf varieties—the harvest takes longer to arrive.

These rootstocks produce medium-sized trees that are resistant to drought and many diseases. Many varieties tolerate frost well, especially if the rootstock is chosen correctly for the growing region. They are often used in orchards where a balance between yield, hardiness, and tree size is important.

Advantages of medium-sized rootstocks:

good resistance to climate change;

developed root system, providing stable nutrition;

high yield in most varieties;

suitable for gardens in the Central and Northern regions;

versatility – successfully grown both in private plots and in industrial gardens.

Flaws:

later entry into fruiting (after 4-5 years);

Some rootstocks may be frost sensitive;

take up more space than dwarfs and semi-dwarfs;

require regular pruning and growth control.

Types of clonal rootstocks for apple trees

Vegetatively propagated rootstocks, known as clonal rootstocks, are produced not from seeds, but from parts of a mature plant—cuttings. Depending on the vigor of the trees grafted onto them, clonal rootstocks are classified into several categories:

dwarf;
semi-dwarf;
medium-sized;
vigorous;
very vigorous.

A clonal rootstock is characterized by complete, 100% inheritance of the parent plant's traits. The name "clonal" stems from the fact that each type of such rootstock is a specially selected, genetically uniform clone.

Intercalary or intercalary rootstock

Intercalary rootstock is a method of growing apple trees whereby an intermediate piece—a scion taken from a dwarf rootstock—is inserted between the seedling (a vigorous base) and the scion. This insertion reduces the overall growth of the tree, making it more compact and early fruiting.

This method produces a plant that combines several characteristics: strong roots from the seed rootstock, compactness and early fruiting from the intercalated rootstock, and varietal qualities from the scion. However, this method has significant limitations.

The main problem is the weakening of the trunk at the insertion point. This makes the tree vulnerable to wind gusts and other mechanical stress. Furthermore, growing an intercalary rootstock requires more time, effort, and care.

Where can I get rootstock for grafting?

There are several ways to obtain rootstock. Follow these recommendations:

Use an existing tree in the garden. Let's say you have an apple tree whose fruit you're not happy with, but a neighbor is willing to share a cutting of an excellent variety. This is an excellent option for regrafting.
Use wild trees as rootstock. They are generally very strong and resilient to adverse conditions, having survived in the wild without any assistance. For example, you can graft cuttings from a cultivar of apple trees onto wild apple trees growing in a meadow.
You can purchase ready-made rootstocks from a specialized nursery. This is probably a more reliable option than using a tree with unknown characteristics that grew from a random seed in a forest or field.

For those who want to control the entire growing process, there's only one solution: growing the rootstock themselves. This is entirely feasible, but it requires patience.

How to grow rootstock yourself?

The easiest way is to purchase a ready-made seedling, plant it, and enjoy the fruits. However, there are quite affordable methods for growing apple tree rootstock yourself. This is not only cost-effective but also allows you to obtain a plant with the desired characteristics.

From seeds

Wild apple seeds are ideal for creating rootstocks, as they possess increased disease resistance and remarkable resilience to all weather conditions, thanks to their natural growth in the wild. Furthermore, they require little special care.

The technology of growing apple trees from seeds includes several stages:

extraction of seeds from an apple followed by drying;
mandatory stratification in cold conditions (refrigerator or basement);
planting in pre-prepared and fertilized soil;
watering and mulching the area after emergence;
picking and pinching shoots after several leaves have formed.

Once the seedlings have strengthened, select the strongest ones and plant them at a certain distance from each other, providing them with proper care.

Clonal rootstock from cuttings

Propagating apple trees from cuttings is a multi-step process that involves harvesting the material in the fall, storing it until spring, and rooting it. Follow these guidelines:

Select a suitable fruiting tree with excellent characteristics for cuttings. The best time to do this is late November or early December.
Cut shoots from the center of the crown, preferably on the south side, choosing mature branches with no signs of frost damage. The ideal thickness is about 1 cm, and the length should be at least 40 cm. It's important to make the cuts correctly: the top cut should be straight, and the bottom cut should be at an angle just below a bud.
You can preserve cut shoots until spring by leaving them under the snow. If the winter is light on snow, store the cuttings in the refrigerator or cellar.
To root, prepare a mixture of equal parts sand and fertile soil. Plant the cuttings in this mixture and cover with a clear bottle to create a greenhouse effect. If you have a greenhouse, you can place the cuttings there directly.
After rooting, transplant the rootstocks into open ground, where they will spend a couple of years until they reach an age suitable for grafting.

Seedling care includes regular watering during the first few weeks, mulching, loosening the soil, and fertilizing. Some gardeners root the cuttings immediately after cutting them into the ground; in this case, the greenhouse requires additional cover.