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What do the different walnut species looks like?
There are two main species
of walnut grown in the UK; the common walnut Juglans regia, also known
as the Persian or English walnut, and the black walnut J. nigra. There
also hybrid walnuts of black x common walnut, often known as J. intermedia,
and others from other species not described here. All walnuts will grow to a
large size, contrary to popular belief, up to 25 metres ( 82 ft) or more, and
have very wide crowns (canopys).
Identifying the different species is not difficult while they are in leaf or
if nuts are present. All walnuts species have compound leaves, having many leaflets
to a leaf.
Common walnut 5-7
leaflets, terminal leaflet large, leaflet margins smooth edged, leaves are aromatic
when crushed. Nuts vary greatly in size and shape but typically have shallow
fissures and the shells are light coloured. The bark is smooth when young and
grey in colour, only becoming fissured after about 15 years.
Black walnut 9-17 leaflets, terminal leaflet small or absent, leaflet
margins finely serrated, leaves are not aromatic when crushed. [picture]
In addition the midrib underside the leaf is covered with fine hair. Leaflets
tend to angle down from the midrib. Nuts vary greatly in size and shape but
typically have deep fissures and the shells are dark coloured. The bark is ridged
from a young age.
Hybrid walnut 7-12 leaflets, terminal leaflet quite large, leaflet margins
coarsely serrated, leaves are not aromatic when crushed. The midrib underside
the leaf is hairless. Leaflets do not angle down from the midrib. Nuts vary
greatly in size and shape but typically have deep fissures and the shells are
dark coloured. The husks are green, lightly textured and very aromatic. The
bark is ridged from a young age.
What are the different species used for?
Common walnut is planted both for its fruit and timber, typically as
separate enterprises. Nuts can be pickled, eaten fresh ('green' or 'wet') or
dried. The fruit, nut husks, bark and other parts of the trees can also be used
in many products, including cleaning products, dyes, inks and medicinal purposes.
Black walnut is mainly grown for timber in the UK but in the USA the
dried nuts are eaten (fresh black walnuts are inedible being very bitter). Black
walnut is generally considered to be more suitable for growing in forest conditions
than common walnut.
Hybrid walnut is grown purely for timber.
Can walnuts be grown for both their timber and fruit?
Growing walnuts as a multi-purpose tree can be rewarding but the landowner must realize that this is a compromise between two different growing systems. Reduction either of timber volume or fruit production must be expected. Not all fruit varieties are suitable as multi-purpose trees. There are no established markets for black or hybrid walnut nuts in the UK at present.
How long have walnuts been around?
Common walnut was introduced to Britain by the Romans, as it was to all of Europe where it is now naturalised. Its natural range extends only as far west as Turkey with its heartland in Central Asia.
Black walnut is native to North America being introduced to the UK in the early 17th century.
Hybrid walnuts probably existed naturally in situations where both parent species occurred.
Several hybrid trees over 100 years old have been found in Europe, although
they are often overlooked being similar in appearance to other walnuts and also
ash. Today they are produced by tree breeders under controlled conditions in
Europe and elsewhere.
When should I plant walnut trees ?
Like most deciduous trees, plant walnut when it is dormant and the leaves have fallen. Preferably before Christmas or from mid February until late March. Late planting, even if the buds are not flushing, is not ideal as the plants are more prone to drying out.
What is the best site for walnut?
All walnuts
species grow best on fertile soils that have a reasonable depth and are well
drained. The ideal pH is near neutral (5.5-7.5). Avoid frost pockets in valley
bottoms and any area prone to waterlogging. They will not grow well in compacted
soils, or those with a gravel layer or iron pan close to the surface. Exposed
sites and those with steep slopes should be avoided. Gentle slopes near the
valley bottom are optimal because cold air is drained away from the trees and
water availability is high.
Hybrids are more tolerant of drier conditions and poorer soils than either common
or black walnut. On marginal sites hybrid walnuts show very strong growth over
the other walnuts but on optimal sites the differences are minimal.
Good site preparation is essential and ideally should involve the break up of any compacted soils, removal of weeds, and if necessary improvement of drainage.
Should I irrigate or fertilise?
Irrigation
should only be considered as a last resort in forest plantations as this will
encourage surface rooting, making further watering necessary (you are making
a rod for your own back!). Plant earlier in the planting season to avoid the
problem.
When trees of 3 to 4 years of age are used to established fruit plantations,
irrigation is beneficial and often required in the first years to ensure successful
survival and subsequent growth. Younger trees can be treated as forestry trees
provided they are planted at the right time.
Walnut is a high nutrient-demanding species particularly for nitrogen (N)
and phosphate (K). Timing of application is important, ideally early
summer. Late application (after August) can cause problems with hardening off
the years growth. Fruit trees require higher levels of nutrients than forest
trees. Leaf discolouration often indicates a nutrient deficiency - consult an
expert for advice.
Mulching newly planted trees reduces the need for irrigation and fertilizers
and is recommended.
Do I need to protect a newly planted tree?
Yes! Protection of a young tree is important to avoid damage from browsing or from
herbicide drift. For a forest plantation the landowner can choose between erecting
a fence or using treeshelters. There are many designs of shelters on the market
and their type/size can affect the trees growth. Contact
us for more advice.
The protection of trees in a fruit orchard is typically similar to those in
forestry plantations.
How long will a walnut tree take to produce saleable timber?
Timber crop rotations are variable between 40 and 100 years dependent on many factors including the walnut species planted and their vigour, their silvicultural management and the desired end product. There are two main timber products: fast-grown wood of pale colour produced using hybrids and intensive silviculture, or the well-known dark figured wood produced by traditional silvicultural techniques over longer periods of time using any of the walnut types. The markets for these are well-defined.
Can walnuts be grown with other trees?
Walnuts grown for timber nearly always benefit from being planted with other species. Contrary to traditional practice, recent research has identified many systems beneficial to growing high quality walnut timber. Choice of companion species is of paramount importance and advice should be sought.
Walnuts trees can live for several 100 years.
Can nuts be commercially grown in the UK?
Walnuts are grown on a commercial scale in the UK but there are few examples. However, there is considerable potential and market demand, both for timber and fruit production.
When will the trees start bearing fruit?
Timber trees will often not start fruiting typically for 8 years or more depending on the silvicultural practices used. In contrast, grafted fruit varieties typically start producing fruit from three of age onwards. Choice of the right species and type is therefore very important.
What's the difference between pickled, wet, green and dry walnuts?
The pickled nut is harvested in late June/early July, before the shell on the nut forms and is typically preserved in vinegar or port.
A wet nut, often known as green, is a fresh mature nut that is consumed soon after harvest(September/October) and has not been dried. It is often described as having a milky flavour.
A dried nut has been allowed to dry out to improve its storability.
All fruit varieties can be used in these different ways but some are more suited for a purpose than others.
I have a walnut tree in my garden but it rarely bears fruit - why?
There can be several reasons.
Where can I get more information?
You can get more information by contacting us. We offer a professional consultancy service for your walnut growing plans, which can include conducting site visits and advice with planting grants. There is also an excellent walnut resource on the world wide web.
I have a walnut on my land that I'd like to cut down and sell. How should I find a buyer?
There are many buyers and, as walnut timber is in such short supply, the timber is highly sort after. Choose your buyer carefully and remember, never fell a walnut as the most valuable timber is in the root-crown area, where the stem joins the roots. Usually walnut trees are therefore dug up rather than felled with chainsaws. A visit to Woodlots may be useful as it covers the whole country.
Is there a network of walnut growers I can join for support and advice?
There are
two networks. The British and Irish Hardwoods Improvement
Programme (BIHIP) includes a Walnut Group that focuses on
timber research and production.
The Walnut Club can provide support and advice, especially
on fruit production.
How can I place an order for trees?
Contact us using which ever method you prefer. We prefer to work closely with you our customers to ensure you get the very best possible advice and service. We will personally confirm your order and let you know when to expect delivery.
Forest trees from WTC are mostly delivered bare-rooted but we can offer a limited range of module-raised seedlings. Grafted fruit trees are delivered bare-rooted. They are delivered to your destination of choice within the UK but please be aware that the trees will need to be cared for on their arrival. Please contact us if you have any further questions.
