Last updated on October 23rd, 2023 at 08:25 pm
Don’t shy away from familiar sizes: a grafted walnut tree fits into the home garden and bears fruit much earlier than a seedling tree. Specialist editor Arne Janssen explains what is important for successfully planting and pruning a walnut and introduces you to varieties for different garden sizes.
Walnuts from your own house tree
A walnut tree is a real garden dream. Behind the rough shell of the fruit hides an aromatic core full of energy, and not only squirrels like that! As a traditional addition at St. Nicholas and Christmas, in pastries, in hearty dishes or freshly cracked in front of the TV in the evening: walnuts are the harvest and consumption highlights for garden owners, and have been ever since they were spread from the Mediterranean region by the Romans.
“They don’t bear”, and “Walnut trees get too huge!”, you may now say. But is the popular walnut tree really only suitable for extensive parks and farms in solitary locations? Not at all! Experts agree on this.
The prerequisite is a walnut graft from the nursery and not a seedling plant given to you by gardening friends. Even if the latter can be had for free: the considerable price of a graft of 50 euros and more pays off, because the first yield from these walnut trees comes after only three instead of fifteen years of waiting.
Grafting also helps to determine the second important point when planting a new walnut tree: the height of growth. Some varieties form small and compact crowns and are thus suitable for medium to large home gardens even without pruning (see table below).
Ordering from a special walnut nursery is therefore worthwhile: regional varieties from the south sprout early and need a long growing season. Walnut trees from the north sprout later, so foliage and flowers are unlikely to fall victim to a late frost at the beginning of May.
Which variety suits my garden?
|Stand space circa, in m2||Description|
|For small gardens:|
|‘Dwarf Karlik 3’||10 m2||new dwarf variety from Ukraine, medium sized fruits, no risk of late frost|
|‘Dwarf walnut||10 m2||early yield, early pruning for bush shape, small fruit, sunny place, for handicrafts|
|‘Buschnut from Finkenwerder’||15 m2||from northern Europe, rich-bearing, robust, very large fruit for the size of the tree|
|‘Europe’||40 m2||compact growth, good yields, early setting, also forms fruits on side buds!|
|For medium-sized gardens:|
|‘Lange van Lod’||50 m2||from Flanders, with 8 cm largest fruit, compact growth, good taste, stable yields|
|‘Lara’||50 m2||large fruits with thin skin, compact, also forms fruits on side buds!|
|‘Weinsberger’||50 m2||large nut, good flavour, small-crowned, susceptible to leaf fungi, only for viticultural climate|
|‘Broadview’||60 m2||new variety from Canada, early and high yield, large nut, healthy foliage|
|‘Geisenheimer’||60 m2||Yield early and regular, proven in all regions, no risk of late frost|
|‘Mars’||60 m2||new variety, noble core, compact, early fruiting, light green and very healthy foliage!|
|For large gardens:|
|‘Red Donut Nut||80 m2||red core skin, sensitive to late frost and leaf fungi, only for viticultural climates|
|‘Börde Giants’||100 m2||from the region around Magdeburg, does not fill the bowl completely, decorative, for handicrafts|
|‘Miracle of Monrepos’||100 m2||new and popular variety, robust against late frost, healthy foliage, strong taste|
|‘Finkenwerder Dyke Nut Royal’||120 m2||from northern Europe, large nut up to 7 cm, fills the shell well, good taste|
|‘Kurmarker’||120 m2||vigorous growth and broad crown, very winter hardy, also for high altitudes, good flavour|
The right location
The site for a walnut tree should be chosen with particular care. To do this, place a long roof batten in the middle of the tree and then observe the shadows cast, also towards the neighbour! On newly built plots, for example, a walnut tree can be used well as a house tree and a striking eye-catcher in the garden.
The fact that hardly anything grows under its crown is due to allelopathy:
On the walnut tree, the leaves send small amounts of cinnamic acid towards the ground with every rain. When they decompose, the autumn leaves release juglone. The inhibitors have the sole purpose of keeping nutrient competitors at bay. Perhaps this is why the leaves are so popular with small animal owners. It has a reputation for promoting animal health in pigeons, chickens and rabbits by driving away mites.
With so much biochemical defence, a nice gravel area with table and chairs is often a better solution than an elaborate perennial planting under a walnut tree, especially as the aromatic foliage keeps flies and mosquitoes away.
Planting and caring for walnut trees
Young graftings in containers are suitable for planting in spring.
Cut through any twisting roots by cutting several times into the root ball. Then dig the planting hole twice as deep and wide as the pot root ball. Plant the plant at ground level, create a watering rim and water abundantly during the first summer. Tie the trunk and leading shoot with coconut rope to the support pole that has been driven in beforehand in the main wind direction. For a good development of your walnut tree, fertilise it with one dose of mature compost per year and then every few years with a little algal lime.
Walnut tree: How to prune it properly
For young gardeners, new varieties such as ‘Mars’ or ‘Europa’ are particularly worthwhile if space is medium. These walnut trees grow to only half the size of old selections and grow compactly even without pruning. The only thing to watch out for in good time are branches that are too low on the trunk and competing shoots towards the top.
Gardeners with experience of fruit should try something that even professionals are reluctant to try, namely pruning walnut trees! It is especially interesting for smaller plots, and it works, you just have to know how.
The basic idea behind it:
Because most walnuts only form fruit on the outer branches and nothing happens inside the large crown, it is better to design a flat roof shape, as with sycamore trees in southern climes, or an open cup shape.
To achieve this, the walnut tree should be pruned from the third year of growth in the last days of July. Then there is no water sprouting and the wounds heal best. If the tree is pruned in winter or spring, the cuts would sap heavily and for a long time, experts say: the tree “bleeds”.
When pruning in summer, all branches growing horizontally outwards are left unattended, but all branches shooting steeply upwards are shortened to three eyes. All hanging branches are then also shortened to 30 centimetres. Externally, walnut trees do not react strongly when pruned at the end of July, but internally the buds become stronger and already produce flowers the following spring.
In the following summer, all steep new shoots are cut back again, but the horizontal branch extensions are allowed to grow. You can also tie down steep branches to close gaps in the crown structure. In this way, compact and richly fruiting walnut trees are created that also fit well into smaller gardens.
What to do with the leaves in autumn?
Run the lawn mower over the large-leaved leaves of the walnut a few times and make a great compost for rhododendrons and azaleas with lawn clippings and bark shredder. Oak leaves can also be added, but no lime.