Mulberry trees

Mulberry trees: choosing a cultivar that will ripen in your climate

Fruiting mulberries of the genus Morus produce compound fruits commonly called mulberries. They should not be confused with blackberries and other bramble fruits belonging to the genus Rubus.

Mulberries are true fruit trees, often vigorous, long-lived and capable of producing heavy crops when the cultivar, position and training method are suitable.

In cool European climates, winter hardiness is not normally the principal limitation for cultivars derived from Morus alba, Morus rubra or their hybrids.

More important considerations include the actual ripening season, the amount of summer warmth required, the vulnerability of young growth to late frost and the ability of the current season’s shoots to mature before winter.

A cultivar may survive extremely cold winters while still producing disappointing fruit because it ripens too late or requires more summer heat than the site can provide.

Fruit colour does not identify the species. Despite its common name, a white mulberry can produce white, pink, red, purple or almost black fruit.

Morus alba, Morus rubra and hybrid mulberries

Fruit colour does not indicate the mulberry species

The common names white mulberry and red mulberry refer to species rather than dependable fruit colours.

A cultivar of Morus alba may produce almost black fruit, while another cultivar of the same species produces cream or pale pink mulberries.

Fruit of Morus rubra commonly changes from red to dark red, purple or nearly black when fully ripe.

Colour also provides limited information about flavour.

Pale mulberries are often exceptionally sweet and honeyed, but may possess little acidity.

Dark fruit frequently develops a richer, more vinous or berry-like character, although excellent and mediocre cultivars exist in every colour group.

Choose according to the documented cultivar rather than assuming that the darkest fruit must possess the best flavour.

Useful characteristics when comparing mulberry cultivars

Choose a sunny and warm position

Plant mulberry trees in full sun, preferably in an open position facing south or west while receiving some protection from cold and drying winds.

Sunlight is required not only for general tree growth but also for sugar accumulation, aroma development and proper maturation of young wood before winter.

Good exposure also allows leaves to dry more rapidly after rain.

Mulberries generally begin active growth later than many early-flowering fruit trees, which reduces part of the spring-frost risk.

A sufficiently late frost can nevertheless damage young leaves, tender shoots and developing inflorescences.

This vulnerability of active growth should not be confused with the winter hardiness of fully dormant wood.

A frost pocket at the bottom of a slope can therefore remain unsuitable even for a cultivar described as highly winter hardy.

Do not plant a large mulberry above a terrace or vehicle

Ripe mulberries detach and fall readily, particularly during wind, rain or bird activity.

Dark fruit can stain paving, garden furniture, clothing and vehicles intensely.

Fallen berries also attract birds, wasps and other animals.

A large fruiting mulberry should therefore not be positioned directly above a terrace, driveway, parking space or frequently used path.

A grassed area or orchard floor allows fallen fruit to be collected more easily and provides room for a clean sheet or harvesting net to be spread beneath the crown.

Pale-fruited cultivars generally stain less conspicuously but still produce soft fruit that can create a slippery surface.

Soil, drainage and water supply

Mulberries tolerate clay, loam, sandy and moderately calcareous soils where the roots remain sufficiently aerated.

The best crops are obtained in deep, fertile and biologically active soil containing a useful water reserve without remaining saturated during winter.

Morus alba generally tolerates imperfect soils and summer drought more successfully once established.

Morus rubra normally expresses its full potential in deeper, richer and more moisture-retentive ground.

These broad tendencies do not replace cultivar-specific information.

Moist soil should not be confused with waterlogged soil.

A deep and structured clay retaining useful summer moisture can be highly suitable, while a compact hollow in which water remains around the roots causes weak establishment and progressive decline.

Work heavy soil only after it has drained sufficiently and no longer adheres as a wet and compact mass.

Drought tolerance does not guarantee high-quality fruit

An established mulberry can survive dry conditions that would weaken many other fruit trees.

Survival under drought does not mean that the tree will continue producing large, tender and juicy fruit.

Water shortage during berry development reduces fruit size, shortens the harvest period and can cause premature fruit drop.

A young tree requires particular attention because its roots still occupy a limited volume of soil.

Deep watering during dry periods is more useful than frequent superficial applications that moisten only the soil surface.

An organic mulch applied to already moist soil reduces evaporation and grass competition.

Keep the mulch slightly away from the trunk and graft union.

Planting a young container-grown mulberry

In regions exposed to late frost, plant actively growing container-grown mulberries during spring after the principal frost risk has passed.

A mature dormant tree may withstand substantial winter cold, while a young nursery plant carrying soft leaves can be damaged by a comparatively light frost.

This distinction is especially important where the plant has begun growing under greenhouse or tunnel conditions.

Prepare a broad area of soil rather than a narrow hole filled with potting compost.

Loosen and cultivate the ground only once it has drained sufficiently and begun warming during spring.

Remove couch grass, bindweed, docks and other perennial weeds carefully before planting.

Position the root collar at soil level and keep the graft union clearly above the finished soil surface where one is visible.

Backfill mainly with the original garden soil, improved across a broad area with a reasonable quantity of mature compost where necessary.

A concentrated mass of rich compost or manure within the planting hole does not provide durable improvement to the surrounding soil.

Water thoroughly after planting to settle soil around the roots.

Maintain a weed-free area and continue watering throughout the first growing season whenever rainfall is insufficient.

Watering should not stop several weeks after planting, as summer drought can interrupt rooting and prevent young shoots from maturing properly before winter.

Seedling, cutting or grafted mulberry?

Does one mulberry tree produce fruit?

The sexual organisation of mulberries is complex and differs according to species, cultivar and sometimes individual tree.

A mulberry may carry only male flowers, only female flowers or both male and female flowers on the same plant.

Pollination is carried mainly by wind.

It is therefore inaccurate to state that every Morus alba is self-fertile or that every Morus rubra necessarily requires a second tree.

The ability to crop when planted alone must be verified for the individual cultivar.

Many named fruiting cultivars have been selected because they produce reliably as isolated trees.

This characteristic cannot be extended to unidentified seedlings or unnamed mulberries.

Planting several cultivars may improve pollen availability where their flowering periods overlap, but it cannot turn a male clone into a fruiting female tree.

For a small garden, a named cultivar known to fruit alone is the simplest and safest choice.

Rootstocks and mature tree size

Many grafted fruiting mulberries are propagated onto seedlings of Morus alba or closely related mulberry rootstocks.

Unlike apple and pear trees, mulberries do not have a widely available and clearly classified European range of dwarfing, semi-vigorous and vigorous rootstocks.

The rootstock may influence soil adaptation, water uptake, anchorage and general tree behaviour.

The natural vigour of the cultivar and the way the tree is trained remain highly important.

A young tree grafted onto an unidentified mulberry seedling should not be described confidently as dwarfing.

For a compact tree, choose a cultivar whose own growth habit is known to be moderate or naturally compact rather than relying on an assumed rootstock effect.

Read our guide to fruit-tree rootstocks

Which wood carries mulberry fruit?

Mulberry inflorescences can appear on new shoots formed during the current growing season and on short laterals arising from older branches.

The precise balance depends on the cultivar and the vigour of the tree.

Regular production requires healthy young growth, but this does not mean that severe annual pruning is necessary.

A tree cut back heavily may produce numerous long and vigorous shoots at the expense of an accessible and balanced crown.

Some cultivars can still flower on the resulting current-season growth, while others lose a substantial part of their potential crop.

Pruning should therefore be adapted to the known behaviour of the cultivar rather than based on one rule applied to every mulberry.

Training a mulberry tree

During the first years, form a relatively low and open framework so that the fruit remains accessible.

Select several strong branches distributed around the trunk and avoid narrow forks likely to split as the crown becomes heavier.

Remove competing leaders and badly positioned shoots while they remain small.

A low crown facilitates harvesting with a sheet or net and reduces the quantity of fruit falling from an inaccessible height.

Do not raise the crown too rapidly, as temporary lower branches help strengthen and shade the young trunk.

Where a large shade tree is desired, a taller clear trunk may be formed progressively, provided that the eventual position of falling fruit has been considered.

How should a mulberry tree be pruned?

Once the principal structure has been formed, pruning should remain moderate.

Remove dead wood, broken branches, strongly crossing growth and shoots that genuinely obstruct access or completely close the crown.

Repeated severe cutting stimulates vigorous regrowth and often makes the tree more difficult to manage rather than permanently smaller.

Mulberries can bleed sap when pruned during the period of active sap movement.

Complete necessary work from late summer into early winter, outside periods of severe frost, and favour small cuts.

Avoid removing large framework branches from an established tree wherever possible because major wounds close slowly and may develop internal decay.

Where an old tree requires substantial reduction, spread the work over several seasons.

Can a mulberry be pollarded?

Mulberry trees tolerate hard cutting better than many fruit trees and have traditionally been pollarded where leaves, shade or a restricted crown were the principal objectives.

Pollarding is not automatically the best system for fruit production.

It creates vigorous annual shoots, requires regular repeated cutting and may reduce or delay the crop depending on the cultivar’s fruiting habit.

A cultivar known to flower on current-season growth may continue cropping after relatively hard pruning, while another variety may produce much less fruit.

Where fruit is the priority, a naturally compact cultivar trained as a low open tree is generally easier to manage than a vigorous variety maintained by permanent severe cutting.

Mulberry harvest season

Mulberry cultivars differ considerably in the date at which their first fruit ripens and in the length of their harvest period.

Actual dates vary according to cultivar, country, exposure, soil moisture, tree vigour and seasonal temperatures.

The calendar is intended mainly for comparing varieties rather than predicting one exact picking date for every garden.

How can a ripe mulberry be recognised?

A mulberry does not develop its best flavour after being picked too early.

The fruit should have reached the characteristic colour of the cultivar, feel soft and detach with almost no resistance.

For white, cream and amber cultivars, colour change may be subtle.

Softness, aroma, sweetness and ease of detachment are more useful indicators than waiting for the fruit to become dark.

A ripe dark-fruited mulberry normally changes from red or purple to the final deep colour and becomes noticeably more tender.

Fruit that requires a strong pull is usually not ready, even when it already appears almost black.

The fruit on one tree does not ripen simultaneously, so several harvesting rounds are normally necessary.

Harvesting mulberries without crushing them

Pick mulberries individually into shallow containers without pressing or stacking them deeply.

The soft fruit leaks juice readily and the lower layers are quickly crushed beneath their own weight.

For a larger tree, spread a clean sheet or fruit-collecting net beneath the crown and allow naturally ripe berries to fall onto it.

The branches can be moved gently, but violent shaking also removes immature fruit and may break heavily laden shoots.

Collect fallen fruit promptly before it becomes contaminated by soil, insects or bird droppings.

Harvest during dry weather where possible and process very soft fruit immediately.

Storage and uses

Fresh mulberries have a very short storage life and tolerate transport poorly.

They should be eaten, cooled, frozen, dried or processed soon after harvest.

Do not wash the fruit until shortly before use because additional moisture accelerates leakage and deterioration.

Mulberries are suitable for fresh eating, jam, jelly, coulis, juice, syrup, sorbet, pastries, fruit leather, drying and fermented preparations.

Pale sweet cultivars can be excellent for eating directly and drying.

Dark cultivars with stronger colour and acidity are particularly useful for jam, juice and syrup.

For freezing, spread the fruit in one layer and transfer it to a container once firm.

Should mulberry fruit be thinned?

Manual fruit thinning is not normally practised on mulberry trees.

A very heavy crop can nevertheless produce smaller berries, particularly when the soil becomes dry during fruit development.

The priority is to maintain adequate water, healthy foliage and a branch structure capable of carrying the crop.

Long ageing branches can become brittle or bend under the combined weight of foliage and fruit.

Balanced formative pruning while the tree is young reduces this risk.

On an old tree, supporting a heavily laden branch may be safer than removing a large framework limb abruptly.

Important mulberry diseases and problems

Which mulberry tree should you choose?

For a cool European climate, prioritise an early or mid-season cultivar known to ripen reliably and produce worthwhile fruit under similar conditions.

For an isolated tree, choose a named cultivar documented as capable of fruiting alone.

For eating directly from the tree, prioritise flavour, tender flesh and a maturity period appropriate to the site.

For jam, juice and syrup, look for productivity, strong fruit colour and sufficient acidity.

For drying, a very sweet cultivar with relatively firm fruit can be particularly suitable.

For a small garden, choose a genuinely compact cultivar rather than relying on severe annual pruning.

For a large garden, orchard or park, a vigorous mulberry can become both a highly productive fruit tree and an impressive shade tree.

Do not choose only from a photograph showing exceptionally long fruit grown in a hot climate.

The best cultivar is one that completes ripening in your conditions, develops a balanced flavour and remains accessible at the size you are prepared to maintain.