MULBERRY BONSAI

Mulberry Bonsai: The Taste of Country Tradition

The Mulberry tree(Morus alba or Morus nigra) is a tree that tastes of history, linked to silkworm breeding and our countryside. As a bonsai tree it is generous and sturdy, prized for its wrinkled bark that ages early and, of course, for the fruits (mulberries) that hang from its branches in summer. The challenge with the mulberry? Managing its leaves, which naturally tend to get large, but with the right techniques, fine, proportionate branching can be achieved.

Origin & species

Native to Asia but naturalized in Europe for centuries, it belongs to the Moraceae family (like Ficus!). It is a vigorous deciduous tree. For bonsai, Morus alba (White mulberry) is often preferred for its slightly more manageable leaves, or the "Bombysis" variety.

Exposure and Microclimate

The Mulberry tree wants full sun and plenty of air.
Sunlight is essential for fruit ripening and keeping internodes short. In midsummer, in the hottest areas, it likes light afternoon shade only to prevent the large leaves from transpiring more water than the roots can drink.

Watering

It is a big drinker. The wide, thin leaves disperse a lot of water.
In summer, never leave it to dry out: water profusely as soon as the soil surface dries. If it lacks water, it will tell you right away by drooping its leaves sadly and risking losing its fruit.

Water quality

It tolerates tap water well, even slightly limey water. It is not a finicky plant.

Substrate

Needs a soil that retains some moisture but does not become muddy.

  • Recommended mix: 50 percent Akadama, 30 percent Pumice and 20 percent quality all-purpose potting soil or Humus.
  • Addition of organic matter is important to support fruit production and high water demand.

Repotting

This is done every 2 years for young, every 3-4 for old, in spring before bud opening. Mulberry roots are fleshy, yellowish and grow strong. When repotting you must be firm and prune the coarse roots vigorously to stimulate the fine roots.

Fertilization

Making fruit requires energy.
Fertilize generously in spring with slow-release organic. If you want to encourage fruit, use fertilizers with more Potassium and less Nitrogen in pre-bloom. Resume in fall to fortify the next year's buds.

Flowering and fruiting

The flowers are inconspicuous (catkins), but the fruits are the jewel. They appear on the previous year's wood.
Aesthetic tip: If the bonsai is small and makes too many fruits, remove some of it. Too many blackberries can exhaust the plant and stop branch growth.

Structure pruning

This is done in winter when the plant is bare. Mulberry heals well but withdraws sap: always leave a small stump when you cut a large branch, which you will trim the next year when it is dry. Always use mastic.

Maintenance Pruning and Defoliation

Let the shoots grow to 5-6 leaves and then shorten to 2.
The queen technique for mulberry is defoliation (total or partial defoliation of the largest leaves) in June. This forces the tree to produce a second canopy of much smaller leaves suitable for bonsai.

Tying & bending

Young branches are flexible but break easily at intersections ("wiggle"). Tie semi-woody branches in summer with aluminum wire, being very careful not to tighten: mulberry bark is soft and living, and will mark in a moment.

Diseases and pests

Hardy plant, but watch out for:

  • Mealybug: Often hiding in the crevices of old bark.
  • Rust: Reddish spots on leaves in late summer.

Winter & protections

Cold-hardy. Protect roots from intense frosts by mulching the pot. Beware of fine branches that may dry out if winter is too windy and dry.

Annual calendar

  • January-February: Winter pruning, treatments with liquid jin (diluted) on the wood.
  • March: Repotting.
  • April-May: Fertilizing, fruit development.
  • June: Fruit harvest, defoliation (if necessary).
  • July-August: Lots of water, full sun.
  • September-October: Fall fertilization.
  • November-December: Cleaning fallen leaves, resting.

Useful products for this bonsai

Mulberry Frequently Asked Questions

Can I eat the fruits of my bonsai tree?
Certainly! They are identical to those of large trees, only in miniature or smaller quantities. They are sweet and rich in vitamins.

The leaves have become huge, how come?
Probably too much water, too much shade or too much nitrogen fertilizer. Next year give more sun and try defoliating in June to make them smaller.

Why do some fine branches dry up in winter?
Mulberry tends to self-prune weak inner branches that don't get light. This is physiological. To avoid this, make sure light penetrates throughout the foliage during the summer.