Mulberry – Easy-to-Grow Berries for Container Gardeners
By Laurelynn Martin and Byron Martin
Mulberry trees have been well loved by historic figures such as George Washington and Thomas Jefferson. Washington, purchased 1500 white and black mulberry trees (‘Morus alba’ and ‘Morus nigra’) in 1774, and used them for presidential plantings. Jefferson grew these fruit trees in Monticello, Virginia where he lined both sides of the road around his house with mulberry trees.
Mulberry trees are popular throughout the world, including Asia, Europe and the Middle East. Lately, the demand for these trees has surged in the U.S. and finding mulberry trees that bear fruit early, grow rapidly and produce sweet berries is sometimes difficult. At Logee’s, we have the perfect varieties of mulberry trees for containers or if you have outdoor space, they can be planted directly in the ground for many years of enjoyment.
Mulberries range from cylindrical to oblong and can get as long as two inches in length. The ripe berries dangle from the stem showing off their brilliant black or deep red coloring. Their taste is reminiscent of a cross between a strawberry and raspberry and the flavor can be slightly sweet to honey sweet. They have been used in ice cream, jams, jellies and pies. The fragile skin of the mulberry has discouraged commercial use of this berry but if you don’t mind purple berry juice stains on your fingertips, then it is well worth growing this tree in your home garden.
The mulberry tree comes from the genus Morus with several prominent species found throughout the temperate areas of the world. The flowers are dioecious being either male or female. Most cultivated mulberries are chosen for their female flowers. These are propagated vegetatively by cuttings, which gives consistent fruiting and growth habits as well as earlier fruiting plants.
Varieties for Containers
We grow several varieties but there are two that make excellent potted plants: Mulberry ‘Dwarf Everbearing’ (Morus nigra) and Mulberry ‘Issai’ (Morus alba). Both varieties fruit in small pots as young plants and they also have a fruiting and flower cycle that repeats itself throughout the growing season.
Mulberry ‘Dwarf Everbearing’ (Morus nigra)
Our ‘Dwarf Everbearing’ can be maintained in small 8-10” pots (or even smaller) and with a little pruning a plant kept this small can continue to grow for years. The fruit, like the plant itself, is small (about ½ inch in length) but abundant in its production and extremely sweet when fully ripe. ‘Dwarf Everbearing’ is a good description of this mulberry plant when it’s grown in a container. If it is planted directly in the ground, it will get much larger but when kept in a pot it stays well contained and fruits abundantly on and off throughout the season.
Mulberry ‘Issai’ (Morus alba)
This mulberry is a Japanese cultivar that flowers and fruits successively throughout the growing season. Its fruit is much larger than the ‘Dwarf Everbearing’ and the growth is heavier with a more open growth habit. It starts fruiting at an early age and can be maintained in a pot for years to come with a little help from the pruning shears.
When grown in cold temperatures during the winter months, these plants are deciduous. As they awaken to the warmer temperatures and increasing day length in spring they flush into new growth. New shoots appear along the branching stems from which flowers and fruit emerge. If kept warm year-round, they will hold their leaves and the flower and fruiting cycle will initiate when the light and temperatures increase.
As a rule of thumb, pruning is done during the winter when the plants are resting. Selective pruning of out-reaching leads (long branches) can be done at anytime of the year. Pruning helps to maintain height and size so it’s manageable for the container. Since fruiting occurs with each new growth, there is little disruption to fruiting.
Soil and Containers
Mulberry plants are very adaptable to different soils. We use a standard peat-based, soil-less potting mix and since these plants have little problem with root disease almost any container is fine. As is always the case for container plants, make sure they have good drainage.
Fertilizer and Feeding your Mulberry Plant
Mulberry plants need fertilizer for healthy growth and any balanced fertilizer can be given throughout the growing season. A soluble liquid fertilizer can be used at a dilute strength when watering once a week. Or, top-dress with an organic granular fertilizer sprinkled on the soil surface once a month. Mulberry plants are moderate feeders and although they will grow like gangbusters if fed heavily, it’s best to go easy on the fertilizer since the fruit production is better if the plant is not constantly forcing new leaf growth at the expense of fruiting.
For best results, Mulberry plants need a full sun exposure when growing spring through fall during the active growing season. Mulberries grow best in a southern exposure with sun much of the day. If you are in a northern planting zone, Mulberry plants can go outside for the summer months. The plant can grow under less light, such as an east or west exposure, but the fruiting will suffer.
When grown inside or under hot dry conditions, spider mites can be a problem. Keep a watchful eye for infestations.
Mulberries can take considerable cold into subfreezing temperatures with a hardiness to zone 7 or 10°F. With wrapping and winter protection, a couple of zones higher (zone 5 or 6) can be achieved for those who want to winter their plant outside. Remember that potted plants need to have their roots mulched in colder climates to keep the roots from freezing and thawing excessively.
One of the best reasons to grow container mulberries is the ease in harvesting the fruit. Plants with ripening fruit can be placed on a table and once or twice a day, berries can be picked up from under the tree as they drop. Also, if grown inside there is no issue with birds competing for the fruit. When grown outside, birds will consume all the berries in a single sitting unless nets are used.