Nötodling in Sweden – From 2: Hasslar

In the second part of the series on the nuts we'll look at hazelnuts, which seems to be the most famous nuts in Sweden. They occur naturally all the way up to Umeå, where there are surviving populations from a previous warm period that lasted for about Sweden. 11 500 years ago when hazel formed forest with linden and oak. Viable populations of hazel is also found around Torsåker in Gastrikland and Southern Dalarna.

These wild hazel bushes (Corylus avellana) provide relatively small nuts and have the tendency to a harvest every two years, then they need to gather force during two summers to produce fruit. Even in processed, great fruity varieties, it has been difficult to breed out this property. Most names varieties of hazel starting to bear fruit after three to four years, and the fruits sitting on last years wood [1]. Most names varieties grown today are of the species C.. Hazelnut eller C. top (which differs very little from C. hazelnut) and many popular varieties, so that for example 'Jättenöt from Halle' are hybrids between these two. The hazel can grow well in shade and thrives on sloping habitats, happy to answer fairly easy, sandy soils mixed with copious amounts of moving water in the soil [1]. It is also in such places as we can find the natural population in Central Sweden. In order to provide fruit needs hazel bush much sun and regular pruning is recommended.

All hazel bushes are wind pollinated, and she has- and male flowers on the same bush. Still, they are usually self-sterile, when she- and male flowers ripen at different times. Pollen is spread early in the year, in February and March, but the very conception occurs only in June. All of the pollen does not survive the long wait between pollen dispersal and fertilization so about 20 % the nuts remain opollinerade [1], even the most refined varieties. As a rule, we need one or more pollination varieties to get a good hazelnut harvest, because he- and female flowers rarely bloom at the same time on the same plant. Wild Hazel is usually recommended as pollinators, likewise cultivar 'Cosford' and the variety 'Lodgepole' (ormhassel), that blooms relatively late and thus can reduce the risk of late extreme cold makes the conception fail, which means that empty nuts produced [2].

The Turkish hazel trees (C. colurna) is a species in the genus Corylus, as opposed to the bush-like C. avellana and C. maxima are enstammad. The tree can be 25 m high and produce large quantities of nuts that are stuck together in clumps of about a dozen nuts. The tree is at least hardy to production zone 4 in Sweden. There are also hybrids between C. colurna and C. hazelnut, C. colurnoides which has proven to be very promising in Danish experimental cultivation, with respect to both crop variety and hardiness [3]. In the spring we get three different hybridhasslar from Westergaard's nursery to Putt Myra forest garden to evaluate how they work in our growing climate.

In Putt Myra forest garden we grow right now Twelve different varieties of great fruity hazel, but it is still too early to assess which ones are the best. So far it seems that the habitat is of greater importance than the variety of how much growth there will be. We harvested a handful of nuts cultivar 'Cosford’ and some nuts of an ornament hazel called 'Aureum’ 2013 and 2012, but got no harvest at all this year. In the literature, recommended varieties 'Lambert Filbert', ’Cosford’, 'Long Early Zeller', ’Waterloo’, 'Nottingham Prolific' and 'Jättenöt from Halle' for our climate [2]. A rule of thumb is that the nuts are doing better, the later they begin their development. Hazelnuts said to provide harvests 0,8 t / ha [2] to 2 t / ha [1], where each tree yields 2 to 4 kg nuts on average. The hazelnuts are among the fat-rich nuts and more on their nutrient content and how it stands out in comparison to other nuts come in a later section of this series.

Next post will be about walnuts, which has much more potential in our climate than many believe.

References

[1] Crawford, M., Nut Crops – Appendices, 2012.
[2] Nylinder, B., Nötodling southern Sweden – with focus on hazel, 2013.
[3] Westergaard, L., 2013 [personal communication].