Tuesday, November 29, 2011

More Fall Chores

These pictures are from Wilt Pruf
One of the last chores for the season is prepping broad leaf evergreens for winter. Broad leaf evergreens sounds like an oxymoron. Most evergreens with which we are familiar are the needled variety, such as firs, pines and spruces. These are trees that have adapted to drier climates by having needles instead of leaves. The needles are green and still undergo photosynthesis but have a lot less surface area so that the moisture inside doesn’t evaporate as quickly. 
Broad leaf evergreens are shrubs such as azaleas, rhododendrons, boxwood and holly. They really aren’t adapted to our climate or soil but yet we still plant them so we do have a little work to do to keep them happy. Because of their broad leaves that stay on the plant all year they are really susceptible to our drying winter winds. The wind flows over the leaf and just dries them out. This is really damaging for azaleas and rhododendrons because they set their flower buds in the fall. If they get stressed during the winter the first thing they do is go into "survivor" mode and drop the buds in order to protect the rest of the plant.

Azaleas at Uncle Bill's house in MD
To keep this from happening you can wrap the shrubs in burlap or apply an anti-transpirant. There are several anti-transpirants on the market. The most widely available are Wilt Pruf and Wilt Stop. These are organic polymers that make a waxy coating on the leaf so the moisture stays in the plant. You can apply it now and then again around Valentine’s Day. These products can also be used on fresh cut Christmas trees, wreaths, roping and porch pots and they do the same thing as on live shrubs: they keep the moisture in so they last a lot longer without dropping their needles. You can also use these products in the summer when planting or transplanting. The polymer coating helps the plant retain moisture and reduces transplant shock.
Be sure to water your needled evergreens, as well as your broadleaf evergreens, when ever the temperature gets above freezing for an extended period of time. All evergreens continue to undergo photosynthesis and transpire during the winter and they need to replace the water they have lost through this process.

The Northern Lights is the tall
yellow plant in the middle
Here is something to aspire to.  This picture on the right was taken at my great uncle's house in Maryland.  There they have the right climate and soil conditions to grow great azaleas without really trying.  Because of our alkaline soils and harsh winters it is really hard for us to grow broadleaf evergreens, especially azaleas.  They do not reliably flower because of the stress during winter.  If you really want to grow azaleas try the Northern Lights series.  These are azaleas that are deciduous.  They survive our winters because they go dormant and drop their leaves.  Are they as stunning as the ones at my uncle's? In a word no, but that is the trade off. 

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