Hello there, and thanks for offering this online resource for information. I’m quite new to tree planting, and was wondering if I could pick someone’s brain for some information before putting a newly purchased (today, as of writing this), Mulberry tree. The tree was purchased through Toronto Tree Mobile service, and will be making it’s permanent home in Southwest Scarborough. It is currently in a pot, and standing just shy of 2ft tall, but I was wondering 1), when would it be safe to put it in the ground and/or how long can it survive in the pot. 2) should it be left outside day/night during the current temperature range of the city (cold at night, decent during the day).
Deciduous trees like the mulberry (Morus alba) should be planted in early spring, as soon as the ground can be worked. It is now late April, and although it’s been a cold spring, warm weather could be right around the corner – I would suggest you plant the tree as soon as possible. Make sure to avoid really hot, dry, windy days to avoid transplant shock. For more details, see Planting a tree: a Toronto Master Gardeners Guide
Trees grown in pots can be kept for an indefinite period before planting, as long as the soil mix does not dry out. Your tree should be fine if left outside as long as there’s no danger of frost (and even in the GTA, I think frost is still a bit of a risk right now). If cold weather is predicted, bring it into a sheltered area like the garage at night.
Your Tree Mobile service has an excellent guide to planting mulberries, among other trees, see Treemobile Plant Selection Guide Spring 2019 and just search on “mulberry”. You’ll see that the tree is hardy to zone 3 (Toronto is zone 6), easy to care for and even tolerates salty conditions. The tree prefers full sun but can grow well in light shade. Be sure to plant the tree in a spot where the fruit will not be a nuisance when it falls – the fruit stains a lot, so avoid planting it near sidewalks, walkways and driveways. Ultimately the mulberry can grow to 9-15 metres (30-50 feet) in height, with a spread of 4.5-6 metres (15-20 feet) – so make sure you give it lots of room.
All the best with your mulberry!