• Walnuts tolerate most soils, but prefer well-drained, fertile, moisture-retentive, alkaline loam (a soil that is not very clayey or sandy)
• Avoid frost pockets and exposed sites – strong winds and spring frosts can damage foliage and flowers. Likewise, nut crops are unreliable north of the Midlands
• Young trees less than 3m (10ft) tall, are easiest to establish and care must be taken to prevent damage to the tap root, so
  Describes a pot-grown plant whose roots are filling the container, densely packed and intertwined. Check the roots of container plants regularly, and re-pot into a larger container before they become pot-bound, to ensure continued healthy growth. The roots of pot-bound plants are unlikely to spread out into new soil or compost without first being physically loosened.

  pot-bound plants should be avoided
• Light shade is tolerated at the early stages of development but full sun is ideal
• Walnuts may be partially self-fertile – the
  Gardeners often use the word variety when referring to a specific plant, but the correct botanical term is 'cultivar'. Whichever word you use, it means a distinctive plant or plants, given a specific cultivar name and usually bred to enhance certain characteristics, such as flower or fruit size, colour, flavour or fragrance, plant size, hardiness, disease resistance, etc. Additionally, it is worth knowing that, botanically, variety has another meaning - it refers to a naturally-occurring distinct plant that only has slight differences in its looks. For example, Malva alcea var. fastigiata differs from typical plants by having an upright habit.

  cultivar 'Broadview' for instance – but cropping is improved if cross-pollinated
• Trees planted in autumn or winter establish best and trees should be spaced 12-18m (40-60ft) apart 
• Apply a balanced fertiliser such as Growmore, at 100g per sq m (3oz per sq yd) in late February, followed by 35g per sq m (1oz per sq yd) of sulphate of ammonia, in late March. Alternatively, you could use dried poultry manure at 200g per sq m (6oz per sq yd)
• Newly-planted trees need to be staked and watered during dry spells in the spring and summer to encourage good establishment. A
  Mulch is a layer of material, at least 5cm (2in) thick, applied to the soil surface in late autumn to late winter (Nov-Feb). It is used to provide frost protection, improve plant growth by adding nutrients or increasing organic matter content, reducing water loss from the soil, for decorative purposes and suppressing weeds. Examples include well-rotted garden compost and manure, chipped bark, gravel, grit and slate chippings.

  mulch of well-rotted
  Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

  compost around the base of the tree will help to retain moisture

Harvesting and storing

The nuts develop in a pitted shell surrounded by a fibrous, leathery casing which splits when the nuts ripen in autumn. Nuts can be eaten at this stage but tend to have a rubbery texture. Usually it is better to dry them which will also mean they keep well. Dry the nuts as follows;

1. Break open a couple of nuts to start with to ensure there is a fully formed kernel inside. If not, do not waste time on the others
2. If the nuts are good, remove all traces of the fibrous casing with a wire brush before storage to prevent mould developing
3. Gloves should be worn when removing the casings as walnuts stain the skin
4. Dry the nuts in a cool oven at no more than 40°C (104°F)
5. Once fully dry, store them in a cool dry place
6. Harvest nuts daily as they are very vulnerable to birds and squirrels

In cooler areas, the nuts may not fully ripen. These can be pickled at the green stage but before the outer casing begins to toughen.

Harvesting walnuts at the later stage when their outer husks have softened and blackened is not recommended as this can taint the flavour of the inner nut.

Walnut trees can be grown with a central leader. Alternatively, prune to encourage the production of side shoots by removing the leader - this also restricts the size of the tree. The side shoots should be pinched at the fifth or sixth leaf to encourage the tree to bush. Regular pruning is unnecessary but, if required, remove dead or crossed branches. Pruning should be undertaken between mid-summer and early autumn as walnuts are prone to 'bleeding' (sap oozing from the pruning cut). Hard pruning is not tolerated.

• Cuttings. Walnuts are difficult to raise from cuttings as rooting is poor
• Grafting. Named cultivars are propagated by whip grafting or T-budding onto one-year old seedlings of Juglans nigra (black walnut) or J. regia (common or English walnut)
• Seed. Fresh seed, from which all the green fibrous husk has been removed, is sown 3cm (1¼in) deep in pots, containing well-drained soil or gritty compost. In the following August, seedlings should be ready to T bud using fresh wood or whip grafts may be made later in the year

'Broadview': disease resistant, relatively slow growing and compact habit, producing a heavy crop of good quality, medium sized nuts after three years. Partially self-fertile but crops better if cross-pollinated.

'Buccaneer': disease resistant, fast growing and upright with good quality, medium sized nuts by a lighter crop than 'Broadview'. Self-fertile and bears after four years

'Lara': disease resistant, newer cultivar with heavy crop of large nuts on a moderately vigorous tree

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Walnuts are largely pest and disease free but may suffer from the following;

• Grey squirrels can devastate the entire crop. Wrapping the trunk with plastic tree guard that squirrels cannot grip and raising the lower branches to 1.8-2.5m (6-8ft) can deter attack
• Walnut leaf gall causes pouch-shaped galls on the leaves but they are insignificant
• Walnut leaf blotch and anthracnose can affect the leaves. There is no chemical control for these diseases but collection and disposal of the diseased leaves can break the life cycle of the infection
• Codling moth may damage nuts

Allelopathy

Walnuts secrete chemicals into the soil which inhibit other plants. This is known as allelopathy. However, the effect is more discernable from Juglans nigra (black walnut) than J. regia (common or English walnut). Tomatoes and apples are said to be especially affected.