Choice of a suitable site for apple production is one of the basic principles of fruit growing that appears in all standard textbooks and articles on apple production. Nothing has changed since this good advice was first put forward centuries ago and, if it is ignored, yields will be variable, especially from varieties that do not have a high setting capability.
Apple trees, provided with an appropriate choice of rootstock, will tolerate a range of site aspects and soil conditions whilst still growing and flowering sufficiently.
- However, in many less favourable situations the trees will fail to be pollinated or the pollen will fail to germinate, grow down the style into the ovary and fertilise the female egg cell in the flower (the ovule).
- Sites which are frosty, or simply cold and windy, at the time of blossoming are particularly unfavourable for pollination and fruit set.
In considering site influences on pollination and fruit set it is essential to pay attention to:
- Site altitude and aspect
- Provision of adequate shelter in the orchard
- Avoidance of frost damage
Site altitude, aspect and slope
The following points should be taken into account when choosing a site for an apple orchard:
- Choose a site which is preferably between sea level and 125 metres above sea level.
- Study the cropping history of previous orchards planted on the proposed site, or of neighbouring orchards.
- If available, study meteorological records taken on the site in previous years.
- Avoid sites prone to spring frosts or sites exposed to cold east or north winds.
- Sites with a slight slope to allow the escape of cold air flows are to be preferred.
- Ensure that there are no barriers (buildings or windbreaks), which impede the movement of cold air off the site and create ‘frost pockets’.
- Apples can crop on north and east facing slopes but fruit size is likely to be maximised on warmer south facing slopes.
- Sites close to large bodies of water tend to be slightly warmer and less sensitive to frost damage.
- Choose a site which is sheltered from strong winds.
Provision of adequate shelter in the orchard
- Plant windbreaks at regular intervals (every 100m) around sites, so as to provide adequate shelter for pollination, but not impede the escape of cold air flows during nights of radiation frosts.
- Choose species such as alders or hornbeam, which are less competitive for water and nutrients than willows or poplars
- Plant at spacings of 1.0m-1.75m apart in single or, if very good shelter needed, in double rows.
- Trim windbreaks regularly and cut to approximately 7m in height.
- Plant windbreaks several years in advance of planting the orchard trees to ensure adequate shelter when the young apple trees begin to flower.
- Where living windbreaks are not available, use artificial windbreaks.