I have a weeping mulberry in my semi-shady Toronto back yard that is about 6′ tall with a 3-4′ wide canopy and was planted 3 years ago. It is healthy and produces berries every year. It is identical to another one in my front yard that also produces berries, but which doesn’t have the weeping problem I am describing. The issue with the back yard mulberry is that the new branches that are growing are sticking straight up or out, not ‘weeping’. I have tried tying these branches down, weighting them, etc. to no avail. What’s up and what can I do? I have seen weeping trees with different levels of weeping which I wouldn’t mind. Will mine do that? What should I do to keep it weeping? I don’t have room for an upright mulberry tree!
Thank you for contacting Toronto Master Gardeners with your question about your weeping mulberry. The weeping varieties of mulberry (Morus alba cvs.) are popular ornamental garden trees. They are, however, very vigorous growers, and it takes frequent pruning forays each season to keep them in shape (more about that below). As well, you should be aware that this species of common mulberry, is of concern as an invasive plant in Southern Ontario. You mention that your trees bear fruit. Please ensure that you pick the fruit thoroughly because mulberries readily reproduce from seed. Many types of animal feed on the berries and spread the seed via their feces. These trees are establishing themselves in forested and other wild areas, and, more importantly, they are outcompeting and interbreeding with our native red mulberry (Morus rubra). The native mulberry is at risk of extinction because of its non-native, invasive relative. If you are interested in reading more about this issue, please take a look at this resource from the Ontario Invasive Plant Council .
From the photo you sent in, it looks like some of the branches on your tree are weeping (growing downward), while others are growing straight up. This is not unusual. It can happen when branches grow from below the graft (where the weeping scion is attached to the species rootstock and trunk), but wayward growing branches are not unusual even on the grafted, weeping, portion of the plant. Pruning the upward reaching branches back to where they meet the trunk (or a large branch) will resolve the problem until next spring (when the cycle will begin again). The resource included with this link to, Hawkes Landscape gives a good description of pruning techniques for weeping mulberry.
If you are hesitant to retain the tree (given that its form is not a nice as your other one), perhaps consider removing it and planting something else (certainly non-invasive and ideally a native tree or shrub). Some great ideas for Native shrubs for shade can be found in our Toronto Master Gardeners Gardening Guide, Gardening with Native Shrubs .