Though the peak of fall color is passing in the Gardens and our Michiana area, I thought I would take time to highlight a group often under-appreciated for their fall color: Quercus genus, or Oaks.
Oak trees are often characterized by coarsely toothed or lobed leaves, as well as tall, stately, branching forms. There are many species of oak native to the United States and North America, growing north into Canada and south into Mexico, but oaks also grow all over the world. Although their specifications vary according to species, oaks generally prefer to grow in full sun. They are not usually picky about soil, and will grow in sand, loam or clay, in acidic or alkaline conditions, as long as the soil is well-drained. Depending on species, they may prefer dry or wet conditions.
Oaks go through three color stages, each of which I find absolutely lovely. The green of summer fades with the cooling weather and shorter days to a range of hues, from wine red to multi-toned oranges, which eventually fade to a range of beautiful browns. Yes, I said beautiful browns. Several species of oak exhibit yellow fall color (often combined with brown), caused by the carotene in their leaves that’s visible after chlorophyll is depleted. Chestnut oak (Quercus prinus), hardy to USDA zones 4 through 8, also turns shades of brown and yellow. Chinkapin oak (Quercus muehlenbergii), hardy to USDA zones 5 and above, is normally not grown for its yellow or brown fall color, as it is fairly undistinguished.
Several species of oak exhibit red fall color, and this hue is more likely to appear unaccompanied by brown. Pin oak (Quercus palustris), hardy to USDA zones 4 through 8, turns a deep red in the autumn, while scarlet oak (Quercus coccinea), hardy to USDA zones 4 through 9, is aptly named for its scarlet fall foliage. The red oak (Quercus rubra), hardy to USDA zones 4 through 8, often combines brown and red fall foliage.
Other oaks simply turn deep browns or copper colors when they change, such as the English oak (Quercus robur), winter hardy to USDA zones 5 through 8. The English oak’s normally green leaves change to a coppery brown in autumn before falling off the tree.
Have you ever stopped to notice the beauty of all the different color tones as you drive a November highway? See what oaks you can identify when you next visit Wellfield.
Josh Steffen, Horticulture and Facilities Manager
Missed Josh’s latest posts? Here you go!
- Wellfield Horticulture Staff’s Favorite Things
- Stratification and Scarification: A Seed’s Path to Germination
- Friends of a Feather
- The Importance of Dormancy in Gardening
- Roll Out the Red Carpet for Squirrels
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Of our native oaks, only the black oak gets notable color. It is not comparable to oaks in other regions, but is impressive enough for us, particularly since it is supposedly more closely related to the evergreen coast live oak than it is to other deciduous oaks! Valley oak just turns dingy brown, but is a grand tree while bare anyway.