Standard-sized vs dwarf rootstock
What is the difference between ‘standard-sized’ rootstock, and ‘dwarf,’ or ‘semi-dwarf’ rootstock? In this article we will outline the main differences between a tree grafted on standard rootstock, compared to a tree grafted on dwarf rootstock. We will also explain why we choose to use exclusively standard rootstock for our apple trees.
By the way, in case you are new to growing fruit trees and are wondering what on earth is ‘rootstock’ and what does it mean for a tree to be grafted – you might want to have a look at our article on the purpose of grafting! For the remainder of this article we will assume the reader has some basic familiarity with grafting and rootstocks.
The appeal of dwarf rootstock
The attraction of dwarfing rootstock is simple: the trees take up less space (though a normal apple tree can also be kept smaller with good pruning), and commercial orchards can therefore plant more of them in the same space.
Their small size also makes harvesting easier, and they produce fruit earlier than standard-sized apple trees.
However, they have some significant disadvantages for growers in colder regions, which we will explain fully a bit further down. First, a little introduction to ‘dwarfing rootstocks’ and what they are.
‘Dwarf’ is not necessarily for any tree!
Here is the first confusion we would like to clear up: dwarf rootstock is mainly applicable for apple trees, and not usually for pear or plum trees.
Plum trees are naturally small, and some cultivars have a growth habit that keeps them even smaller than others.
Dwarfing rootstocks for pear exist, but are not as common as for apple trees; some have issues with compatibility and most have not yet been confirmed winter hardy in climates of northern Canada.
However, dwarf and semi-dwarf apple trees (i.e. apple cultivars grafted onto dwarfing rootstock) are very commonly found in many, if not most orchards in North America. Therefore, when we refer here to ‘dwarf vs standard’ rootstock, we are talking about apple trees.
What are ‘standard sized’ and ‘dwarf’ rootstock?
A ‘standard sized’ apple tree simply refers to a cultivar that has been grafted onto a normal apple tree, usually grown from an apple seed.
It will grow into a full-sized apple tree, about 7 metres (23 feet) in height at maturity.
What about dwarf rootstock, where does that come from?
Occasionally when many trees grow from seed, one occurs with traits that make it grow differently to the majority. Dwarf apple rootstock originates from one particular apple tree that is far weaker, slower to grow and less vigorous than most.
In nature this would be a disaster and the tree would not be likely to survive for many decades. When these trees begin to produce early, it is therefore a survival mechanism for them; they need to reproduce themselves as quickly as possible before they die.
But for commercial apple production this is considered a fantastic quality! When a tree like this is found, dwarf apple rootstock is then produced from it. This is done by using ‘layering’ techniques to essentially reproduce thousands of clones of this one dwarf tree. These are then sold to nurseries to be grafted.
Dwarf vs standard sized rootstock: vigour, resilience and productivity
Dwarf trees, being inherently weak growers, require more maintenance compared to trees grown on standard rootstock. They have shallow root systems, and need to be supported with a stake throughout their lives.
They also usually cannot survive without constant irrigation, and they have difficulty competing with grass growing near the base of the tree.
Although they are supposed to be early producers, in cold climates they may winterkill before producing any fruit, or produce very poorly.
In contrast, standard-sized apple trees have root systems that can withstand some competition with other plants after establishment (they will still need to be weeded in their first two years), and do not require constant irrigation (though they still need to be watered during extreme droughts.)
They are strong, vigorous, and therefore have greater ability to fight off disease and repair themselves in the case of any injuries. Finally, the yields that they produce will be many times greater than that of dwarf trees.
Dwarf vs standard sized rootstock: cold-resistance
One of the main difficulties with using dwarf rootstock in colder climates is that, in our experience, it lacks sufficient cold resistance in zone 4 or colder. This means that no matter which cultivar is grafted on it, the entire tree will not be properly cold-hardy.
If even a very hardy cultivar like September Ruby, for example, is grafted to a dwarfing rootstock produced in the Netherlands, the effect will be like sending somebody to hike in -30°C, wearing a big heavy winter parka, but with only shorts and sandals on their legs (i.e., a recipe for disaster).
A hardy cultivar also needs rootstock that is cold-resistant and strong. We select seedling apple trees that are proven to be exceptionally cold resistant for all our most cold-hardy cultivars (the main varieties we use are Antonovka, Dolgo and Baccatta.) More details on hardiness can be found in this article.
Dwarf vs standard sized rootstock: longevity
Probably the most blatant difference between standard sized apple trees and dwarf apple trees is their longevity, particularly in northern climates.
Dwarf trees will live for a maximum of about 20 years – but in our experience they don’t even survive that long. They will often need to be replaced much earlier due to problems with disease, poor health or poor production.
By contrast, full-sized apple trees on standard rootstock will live for about 100 years on average, sometimes even more. (The apple tree that is thought to have been the oldest in North America died in 2020 at the age of 194!)
Think about the implications of this: if the generation of your parents had planted apple trees on their land, you would probably not need to be thinking about planting an apple tree now, but instead would be planning what to do with your huge harvest of apples!
But that is only true of full-sized apple trees. While dwarf apples serve only the one who plants them for a relatively short time and with much maintenance, full-sized apple trees go on to serve two or three generations more!
This text is not to be misread as completely denouncing dwarf rootstocks. They certainly have many advantages, and from the point of view of commercial orchards in zone 5, whose main concern must be profitability, they are unquestionably the way to go.
On the other hand, at Hardy Fruit Tree Nursery our aim is to provide the opportunity for home gardeners in northern climates to grow their own fruit.
Our preference for standard-sized rootstocks is therefore primarily based on our concern for 1) hardiness and viability in northern climates, and 2) longevity, sustainability and the possibility to benefit future generations.
As a secondary point, their greater resilience and vigour makes them easier for the average home gardener to grow.