Written by: Bill Reichenbach, Certified Arboirst WI-01888
Posted: 2018 | Plant Health Care | Tree and Shrub Care | Winter
Birch are highly coveted trees known for their extremely ornamental bark, pretty fall color, and fine textured growth habit. They have been important trees in folklore, useful for woodworking, and utilized in the cosmetic and pharmaceutical products. You can even make beer from the sap. Birch trees fit into our psyche like ‘mom and apple pie’.
The most common birch species in the local Wisconsin landscape are paper birch, river birch and ‘Whitespire’ birch. There are some newer varieties coming into the market place that
show promise. However, birch do have a reputation for being a bit finicky to grow. That being said, there are many birch trees out there gracing our landscapes. So what is the secret to growing a nice birch tree?
- Birch have shallow root systems and prefer a cool moist soil, avoid planting them in hot dry situations. Avoid areas near large amounts of pavement for example. A northern or eastern aspect is better than a southern exposure. Most importantly is the use of bark or wood chip mulch over the root system – the bigger the area the better. The planting of perennials, ground covers and shrubs will enhance the mulched area and help protect the roots and keep the soil cool. Using compost to increase organic matter prior to mulching and planting is also beneficial.
- In times of extended drought, water birch trees thoroughly, giving the trees the equivalent of 1”-2” inches of rainfall per week.
- Some common insect pests of birch need control. White bark birches are susceptible to bronze birch borer, which can kill stressed birch trees. Yearly soil injections of systemic insecticides have proven very effective at warding off bronze birch borer. The same treatment has the added benefit of deterring Japanese beetle feeding and birch leaf miner.
- River birch and ‘Whitespire’ birch often suffer from chlorosis. Visible symptoms of chlorosis are pale green or yellow leaves lacking chlorophyll. Severe chlorosis can result in the loss of the tree. Avoid planting these trees in highly alkaline soils. Most trees will benefit from yearly soil injections of iron and other micronutrients. Trees that are more stubborn may need a trunk injection of iron to alleviate chlorosis.
- As with most trees improving vigor with soil injected fertilizers, root biostimulants, compost teas and mycorrhizae all help to increase pest resistance.
I still think the good old ‘paper birch’ is the birch of choice for our area; it is the most beautiful of trees. I have a nice specimen in my yard and have it treated yearly with soil systemics. It is thriving with thimbleberry, anemone, and hosta growing around the tree. I do like the river birch as well; the vibrant cinnamon brown / orange flaky bark is quite an attraction. Personally, I probably would avoid ‘Whitespire’. This species does not seem to grow well in most of our area soils.
Here is a poem that sums up the birch:
“Beneath you birch with silver bark
And boughs so pendulous and fair,
The brooks falls scattered down the rock:
and all is mossy there”
Samuel Taylor Coleridge