Nuts are rich in protein and have a high calorific value. In terms of food, they can give a very good return on energy invested. For this reason nut crops could play an important role in future food security in Ireland.
The wild hazelnut has a very long history of use as food in Ireland. Remains of shells have been found in ancient cooking sites dating back as far as Neolithic times. The hazel tree was also used for firewood, and its straight rods were valued for construction purposes.
Cobnuts and the closely related filberts are cultivated forms of hazelnut that can be traced back to the Middle Ages. The trees are easy to grow and once established can live for a century or more. Both cobnuts and filberts begin cropping at a young age, and generally produce larger and sweeter nuts, and much heavier crops, than the wild hazel.
When to plant
Planting of bare-rooted trees should take place between November and the end of April, but not at times when the ground is either frozen or very wet. Container-grown trees can be planted all year round, but should be watered regularly if planted during late spring or summer.
Where to plant
Cobnuts prefer slightly acid ground (pH 5.5-6.5) but also do well in neutral or even slightly alkaline ground (pH 7-7.5). Adequate moisture is essential, especially during late spring and early summer. Soils should not be too fertile: very rich ground encourages vegetative growth and may delay or hinder nut production. On the other hand, sandy or gravely soils with low organic content have poor nutrient and water-holding capability, which can lead to the trees suffering drought during periods of dry weather as well as being deprived of essential nutrients.
The ideal site will be well drained, have low exposure to prevailing winds and be in a sunny location not subject to late frosts. A slight slope may also be advantageous. A common mistake made by people planting cobnuts is to throw them into a piece of infertile waste ground, where the trees are obliged to compete with all manner of briars, thorn suckers and the like. In such situations, nut yields are always going to be poor. Although cobnuts will grow in a hedge situation, nut yields are up to ten or twenty times higher when grown as stand-alone trees.
How to plant
Spacing between trees should generally be 3-5 meters, with the narrower spacing for more exposed sites. Except where large trees are being planted on relatively exposed sites, staking is not necessary. If planting on a slope, do not attempt to mimic the angle of the adjacent ground but leave a level area around the tree. This helps capture rainwater during spring time. Young cobnut trees are not particularly tolerant of weeds and the area around the trunk should be kept weed-free for at least five years. A mulch of thoroughly wetted newspaper makes a handy weed-suppressant, and will rot into the ground in time.
Cropping generally begins after two or three years, with a rapid rise in yield each year for the first 10-12 years. In an orchard situation, average yields of 1-3 tonnes per hectare are achievable.
Cobnuts are not self-fertile and will only produce nuts when there is pollen available from another variety or from the native hazel. One of the main reasons for cobnut trees not producing nuts is the lack of nearby pollinators. Generally it is advisable to plant at least three or four different cultivars in the same area.
Sources of fruit trees
Fruit and Nut (www.fruitandnut.ie) supply a comprehensive range of container-grown and bare-rooted cobnuts and also will undertake site assessments and/or provide free advice over the phone or by email. Phone 087 6714075 or email firstname.lastname@example.org.
Next week Walnuts in the west of Ireland