Fruit and Nut
We offer a very wide range of nut species and cultivars suitable for Irish conditions.
Nuts and hedging
There is a lot of confusion about nuts and hedging. This reflects the very different prospects for nut production for different types of nut tree, and the poor understanding among some gardeners and many horticultural retailers of the significant difference between obtaining the occasional nut and a getting a decent crop.
Cobnuts in hedges
While Spanish chestnut and walnut trees can be grown as specimen trees in hedging situations, with potentially good yields in the long term, cobnut trees grown in hedges nut very poorly compared to ones grown in more open situations. Typically, yields from cobnuts grown in hedge situations will be around one tenth of the crop from a well-trained tree in an open situation. The reasons for this are fairly clear: the female flowers develop mainly on side spurs in open, sunny, situations. In dense hedges, opportunities for the development and subsequent pollination of female are much more limited. Where cobnuts do develop in hedge situations, they are often high on the tree and out of reach.
If nut yields are the main objective, cobnuts should be grown in open situations at spacing of 3.5-5 meters between individual trees. The trees should be trained similarly to apple trees, with side spurs encouraged whilst simultaneously avoiding overcrowding of branches by judicious pruning. The trees should be trained as a standard with a main trunk, not as a bush with multiple stems rising up from below ground level. In order to increase pollination prospects, at least two different cultivars (varieties) of cobnut should be planted.
In hedge situations, where shelter or privacy are the main concerns, the common hazelnut represents a more economical choice.
Chestnut and walnut trees in hedges
Growing Spanish chestnuts and walnuts in hedge situations works best where the trees can be established prior to the hedge. Where a hedge is already in situ, it is recommended that a two meter length of hedge is cleared back in order to make space for each tree to be planted. As the nut tree becomes larger, the hedge can be gradually allowed to grow back. It is advisable to prune away any side branches that emerge on the lowest 2.5-3 meters of the nut trees. This will make it easier to develop a good spreading shape above the hedge.
In order to increase pollination prospects, at least two different cultivars should be planted. Spacing should be 8-12 meters between trees. Unless a considerable length of hedge is available, it is probably advisable to concentrate on one type of nut tree. As walnut leaves can suppress the growth of some other tree species, chestnuts might be the better choice.
Growing Nuts from Seed
Although the common hazel (Corylus avellana), the common walnut (Juglans regia), and Spanish or sweet chestnut (Castanea sativa) can all be successfully grown from seed, the eventual nut yields will be very poor compared to cultivars propagated by cutting, stooling or grafting specifically for nut production.
Cobnuts (cultivated forms of the common hazelnut) grown from nut will not necessarily come true to seed, and may take many years to reach nut bearing age, compared to three or four years for named cultivars propagated vegetatively.
Both chestnuts and walnuts grown from seed collected locally (should any be available) have a reasonably good chance of eventually producing some nuts providing pollination requirements can be met. However, trees grown from seed may take as long as two decades to reach nut-bearing age, compared to six years or less for named (nut producing) cultivars propagated by grafting or cutting. Also, the occasional production of nuts from trees grown from seed should not be confused with the more substantial and regular crops achievable with named cultivars. When the seed has not been collected locally but brought in for another climatic region, the outcome is even more uncertain.
Unfortunately, the confusion is perpetuated by some mainstream horticultural retailers and nurseries selling young seed-grown chestnuts or walnuts as 'nut' trees. While seed-grown plants will certainly grow into fine attractive trees valuable for timber or - in the case of the chestnut - coppicing and fuel production, regular production of nuts is unlikely.
For anyone wishing to grow chestnut or walnut trees for purposes other than nut production, young seed-grown trees can be purchased very cheaply.
In addition to the long term potential for timber production, experimental plantings of low-cost seed-grown chestnuts and walnuts can also be used to determine soil suitability in situations where named cultivars may be considered at a future date. This may be useful on marginal sites, especially those with potential drainage problems (see below). Seed-grown trees can also be used as rootstock for grafting purposes.
Growing Nuts on Difficult Sites
While there is no substitute for deep well drained soil on a warm sunny site, nuts are still worth a try in many other locations.The information listed below will help clarify what type of nut will grow in different situations.
Annual precipitation in excess of 1500mm will largely rule out chestnuts and walnuts. In such circumstances, cobnuts are the only viable nut. Walnuts may be considered viable in areas with rainfall of under 1000mm, and marginal at 1000-1200mm. Chestnuts are potentially viable in areas of under 1200mm precipitation, and marginal at 1200-1500mm. Outside of these parameters, success is uncertain. However, higher rainfall may be tolerated in the warmer climate of the southwest.
Altitude has the effect of shortening the growing season. The maximum altitude for chestnuts and walnuts is likely to be under 150m in most of the country, but somewhat higher in the southeast. Cobnuts are likely to be viable to around 250m, and up to 350m in sheltered sunny sites.
Late frosts may be a problem with both walnuts and chestnuts. With walnuts, leafing out occurs from mid April to mid May, and flowering from late April onwards. Chestnuts flower after the last frosts but leaf out from early April to mid May. In both cases, early leafing cultivars should be avoided in areas prone to late spring frosts. Early flowering cultivars of walnut should also be avoided.
In frost-prone areas, careful choice of site may reduce the risk of frost damage. On still nights, cold air flows downhill to settle in hollows and valley bottoms. Sloping ground is much less prone to late frosts.
Exposure to wind
Exposure to wind, especially salt laden winds coming from the Atlantic, is not condusive to nut production. However, shelter can be created by planting hedges and shelterbelts. Alder is strongly recommended as it grows quickly and also improves the soil through the action of nitrogen-fixing bacteria on its roots. Alder can be coppiced if it gets too big, and will form quite a dense barrier to wind.
Chestnuts and walnuts strongly dislike waterlogged ground and will probably fail completely within a few years. Even where the trees survive, wet soils will increase the risk of fungal or bacterial infections and other tree health problems. Both chestnuts and walnuts require at least a meter of good drainage in order to do well. If the water table cannot be lowered through drainage, cobnuts are probably the only hope. If the ground is badly waterlogged, then even cobnuts will not succeed.
Acid and Alkaline soils
Cobnuts and chestnuts are best with a pH of 5.5-6.5 while walnuts prefer slightly more alkalinity (pH 6.0-7.0). Soils with extreme acidity may be sweetened with lime or regular doses of wood ash, alternated with well rotted compost.
Cobnuts and walnuts can tolerant alkaline soils up to a pH of 7.5. Such soils are relatively unusual in Ireland, though may sometimes be found on limestone. Chestnuts do not do well in alkaline soils. However soils with a pH of higher than 6.5 may be acidified locally with heavy dosage of turf mould, unrotted bark or pine needles.
None of the nuts like shallow soil. Cobnuts are the most tolerant but will tend to grow very slowly, especially if there is competition with grass or other vegetation.
For cobnuts, a simple solution is to dig a wide hole to a depth of 0.6-0.8 meters, breaking up the subsoil with a crowbar or pickaxe. The hole should then be filled with fresh soil.The new soil should have a moderate humus content but not be too rich as this will delay cropping. The cobnut should then be planted into this. Animal manure should not be used.
Both chestnuts and walnuts have strong tap roots and benefit from deep soils. In order to grow them on shallow soil, it will be necessary to excavate a hole at least 1 meter deep and wide. In the worst cases, where shallow soil lies on top of hard gravelly sub-soil, the hole should be excavated to 1.5-2 meters. The hole should be back-filled with friable, humus-rich soil containing some stones (for drainage). Animal manure should be avoided. A mechanical digger will make light work of the operation.
Provided there is adequate drainage, both chestnut and walnut trees will be able to develop good root systems in this type of situation. If the hole shows signs of seepage and filling up with water during excavation, the water table is probably too high, or drainage inadequate.
On very difficult ground, an additional strategy would be to make a large raised bed over the filled-in hole. This can be up to 0.8 meters in height and three meters across, and can be retained with a stone wall. This will provide extra depth for the tap roots and get the trees off to a really good start.
Sandy soils are often low in nutrients and are poorly tolerated by chestnuts and walnuts. However, providing the soil is reasonably deep, the situation can be improved by digging out large holes for each tree - similar to suggested above - and filling with humus-rich soil. Regular mulching with partially rotted tree bark or forestry wastes will also be beneficial.
Another factor to consider when planting nut trees is global warming. As a consequence of anthropogenic greenhouse gas emissions, planet earth is expected to rise by anything up to 4 degrees Celsius in the next 100 years. A rise in temperature of 2 degrees Celsius - a near certainty within the lifespan of most nut trees planted today - will increase the viability of many species and cultivars of nut trees. Each 1 degree rise in temperature is equivalent to being 250km further south. For an idea of what sort of climate Ireland will have in 80 years time, visit Western France or Galicia.