




The tree of heaven (Ailanthus altissima) is a rapidly growing deciduous tree native to China that has become a widespread invasive species across North America.
Known by a number of names including stinking sumac, Chinese sumac, varnish tree and stink tree, the plant releases a strong, offensive smell, particularly from its flowers.
The tree of heaven was brought from China to the United States in the late 1700s as a horticultural specimen and shade tree. Its ease of establishment, rapid growth and absence of insect or disease problems made it popular when planning urban landscaping.
These same traits have led it to spread aggressively throughout the United States, crowding out native plants wherever it establishes itself.
Tree of Heaven seeds are relatively easy to germinate and grow. The dormancy within the seed is short and easily broken.
The seeds first need to be soaked in water for between 48-72 hours. The water should then be fully drained and the seeds mixed with a little damp sand and placed into a plastic freezer or zip-lock bag and placed into the fridge for at least 4 days. This period of cold will greatly increase the number of seedlings that germinate compared to untreated seeds and will also enable faster seedling emergence. Please note that sometimes seed lots require a longer period of cold pretreatment, occasionally as long as 8 weeks.
Blackhaw viburnum thrives in U.S. Department of Agriculture plant hardiness zones 3 through 9, meaning that it can be grown in most parts of the U.S. It’s widely available at nurseries and garden centers. Blackhaw is usually grown as a multi-stemmed shrub, although it can be trained as a single trunk tree. It grows up to 15 feet tall and 12 feet wide, so choose a roomy place for this long-lived shrub to spread.
Amend the soil with compost or manure before planting to improve drainage. Blackhaw tolerates both sun and partial shade, although it will bloom better in full sun. Plant blackhaw outdoors in spring or early fall for best results. Water the soil well immediately after planting.