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Gardening Answers Knowledgebase

Plant Answer Line Question

Keywords: Leaf marcescence, Leaf abscission, Hamamelis

I'm wondering if there is a way to get the leaves to drop off of my witch hazel in the fall, or before it blooms?

Answer:

Some witch hazels have a habit of holding onto their dead leaves (this is called marcescence). Leaf drop (leaf abscission) can also be affected by weather patterns or by the age of the tree. The only way to get them off the tree before they finally do it themselves is to remove them by hand.

An article by Phil Clayton, published in the January 2007 issue of The Garden, mentions that some yellow-flowered varieties have this trait. Here is an excerpt which quotes Hamamelis expert Chris Lane:
A (...) free-flowering yellow selection (...) is H. x intermedia 'Ripe Corn'. The only downside is its habit of hanging onto old leaves as the flowers open. This trait occurs in some other cultivars and is usually frowned upon by growers (...) a mild autumn followed by a sudden frost can make more leaves hang on to branches. Fortunately, as with H. x intermedia 'Ripe Corn', older plants often grow out of the habit.

An article entitled "Ranking the Scents and Sights of Hamamelis" from the February 25, 2011 posting in Swarthmore College's Scott Arboretum Garden Seeds blog also includes a chart "Ranking Leaf Retention and Fragrance of Hamamelis."

Date 2016-09-02
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Plant Answer Line Question

Keywords: Leaf marcescence, Leaf abscission, Quercus, Fall foliage

I have a large lawn with a southern exposure, and fairly good drainage. I would like to plant 1-3 large shade trees. I have been considering northern red oaks for the location, as they seem to grow well in this climate, should provide good shade, and they have nice fall color. However, I don't like oaks which keep their dead leaves through the winter (as Scarlet oaks do). I find the dead leaves unsightly and messy, and I will not want the shade in the winter. Do red oaks also keep their dead leaves on their branches in this manner? If so, have you another recommendation, other than maples?

Answer:

According to the Sunset Western Garden Book, pin oak (Quercus palustris) keeps its brown leaves through the winter, but Northern red oak (Quercus rubra) loses them in fall. The retention of leaves in fall (meaning that they delay dropping them until spring) is a phenomenon called marcescence. At times young trees of other oak species, even Quercus rubra, can keep their leaves all winter, particularly if it is an unusual winter. You might consider Katsura tree (Cercidiphyllum japonicum) or sweet gum (Liquidambar styraciflua) for fall color with more reliable leaf drop.

Date 2016-12-22
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April 11 2017 13:50:16