Mulberry Trees (Morus rubra [red], alba [White], nirga [black]) are medium to large, spreading, deciduous trees. The taxonomy of mulberries is complicated and disputed, with 150 species named, but only 10-16 generally cited by botanical authorities. Mulberry taxonomy is further complicated by the ability of many species to cross-pollinate with each other and form fertile hybrids. Three species are commonly referenced in the horticultural trade. The red mulberry is native to Eastern North America, the White to Eastern Asia, and the Black to Southwestern Asia. We have so far only dealt with the red and white species, and I can’t find any good information for distinguishing them from the black. The characteristics used to differentiate red and white are a matter of degree, necessitating comparison of actual samples in order to understand how to differentiate the species. Red mulberries have more hair on the undersides of the leaves; the small veins are more impressed into the leave surface, which is less shiny. Also, the teeth along the leaf margin of the red species are narrower. We were previously unable to differentiate red and white mulberries, because the tree we used as the example of a red mulberry, to compare with the white mulberry, was actually also a white.
The varieties we propagate are clones of female trees, selected for their fruiting characteristics. 6th st is a white mulberry (that we used to think was a red one) that produces abundant large (for a white mulberry) fruits. The fruits ripen to nearly black and have a good sweet flavor. White is a rare white-fruited white mulberry. The fruits are very sweet. Everbearing is a commercial variety reputed to be a red-white hybrid, but shows mostly white characteristics. It leafs out much later than other local trees, and the fruiting season is extended. The fruits are small, but have a good sweet flavor. Cedar Key is either a red mulberry or a hybrid with mostly red characteristics. The fruits are quite large and the best flavored of any we’ve sampled. It leafs out earlier than many local trees and is at greater risk of damage by late frosts. I have observed this variety to grow branches exceeding 8’ in a single year. We have identified some actual wild red mulberries and will investigate their fruiting characteristics and select some for propagation.
Soil: Mulberries tolerate most soil conditions, but are more commonly found in areas with more fertile soil, containing clays, and higher pH (5-7), and greater water-holding capacities. Light fertilization may speed the tree’s early growth.
Water: Established trees should not need irrigation, but it may improve fruiting during droughts. They seem to like areas near water, such as creek banks.
Sun: full to partial shade. Fruit production is probably greater in full sun.
Cold: Can tolerate very cold weather if fully dormant. Once dormancy is broken, they can lose new leaves and fruits to frost, and even branches if the freeze is hard enough.
Pruning: Prune to a strong spreading structure, by standard pruning practices, such as eliminating internal crossing branches and declining limbs. You can also use drop-crotching and heading to keep the tree short to facilitate easy harvesting. Young trees may send up a shoot from near the bottom that will become the main trunk. Cuts of more than 2″ diameter may not heal and should be avoided.
Propagation: By cuttings in the late summer. Seedlings may not be true to type and could even come up male.
Pests: a scale insect is a bad pest in our nursery, sometimes killing potted trees during the winter. We rub them off the branches. I haven’t seen this pest be problematic in out-planted trees. Many insects and birds will infest or eat the fruits. The fruit may also have thrips (very tiny insects) crawling around and between the fruitlets, which some people may object to eating, though they are not noticeable.
Other problems: Fallen fruits and bird droppings can be messy.
Harvesting, storage, and preparation: The easiest way to harvest is to spread sheets under the canopy and shake branches. You’ll have to sort out the bad fruits. Ripe fruits should release easily from the branch. I usually chew around the stem and avoid eating it. The fruits cannot be stored fresh for any length of time. Freezing, canning, fermentation into wine, and dehydration may be effective storage methods. The fruits can be eaten raw, used in pies, jellies, and other dishes. Use your imagination and let us know about any successes.
More photos on Flickr: https://www.flickr.com/search?sort=relevance&text=Morus%20rubra
pdf – Information sheet (to print out)