Friday, September 25, 2009

Re-Blooming Poinsettias

How do I get my poinsettia to re-bloom? I normally get this question after Christmas but I just had a question today about how to get a poinsettia to bloom for Christmas.

If you saved your poinsettia from last year, it is time to start thinking about the re-blooming process. By now you should bring your plant back indoors if it has been outside over the summer. Continue to provide bright light and keep the soil in the pot moist.

In early October you should begin to provide different treatments during the day and night. During the day you should provide bright light and a temperature between 70-80˚. During the night you need complete, uninterrupted dark and a temperature between 65-70˚. The plant needs this uninterrupted dark in order to produce the colored bracts. Keep the plant in a closet or other completely dark location from 5pm till 8am each night.

Continue this schedule till around Thanksgiving when the bracts begin to develop color and then discontinue the day/night treatments. At this time it is important to provide at least 6-8 hours of high intensity light until the bracts are completely colored. Once this happens you can move the plant to the location where you want to display it for the holidays.

I usually tell people to not even try to re-bloom poinsettias because it is much easier to simply buy a new one each year. But if you must try, I hope this helps and let me know if you are successful.

Thursday, September 10, 2009

Dogwood Defoliators

I have seen at least five samples of red twig dogwoods here in the Extension office with completely defoliated twigs. The culprit is known as the Dogwood Sawfly. Dogwood Sawfly, Macremphytus tarsatus, is a significant pest to dogwood (Cornus) species. Because the Dogwood Sawfly takes on several forms while in the larval stage, it may not be easy to identify. The larvae strips plants at the end of season, normally just before late August.

The wasp-like adult sawfly lays eggs that hatch into larvae, the first instar of which is an almost translucent yellow. Look for groups of these larvae on the undersides of leaves that are being skeletonized. The second instar appears to be covered with a chalky powder, and the last instar is a one inch long creamy-yellow larva that has a shiny black head and black spots (see photo).

Normally damage is short lived, therefore control is not warranted.