City planting trees in December despite winter temperatures

Despite the hoopla city officials made over the milestone, they invited no press to witness it or ask questions.

• This may be because the mayor has been criticized for rushing to plant the last several thousand trees in late fall, which the Morton Arboretum says risks "poor root growth and increased failure rate."

What they're saying: "Ideally, you will plant trees when the air temperatures are moderate to cool, which is easier on the plants," Morton plant clinic manager Julie Janoski tells Axios.

• "You also want soil temperatures to be above about 45 degrees because below that, tree roots stop growing. A new tree needs to establish its root system in order for its systems to function properly."
• The planting occurred Dec. 1, when temperatures hovered in the 30s.

The other side: Officials at Streets and San, which oversees forestry, tell Axios that fall planting "typically ends when the ground freezes. Ground temperatures are closely monitored... and adjustments are made in tree planting when necessary. "