Extension News

Ask the ISU Extension Gardening Experts

Note to media editors:

Got gardening questions? Call the Hortline at (515) 294-3108, Monday-Friday from 10 a.m. to noon and 1 to 4:30 p.m., or e-mail us at hortline@iastate.edu. For more gardening information, visit us at Yard and Garden Online, http://www.yardandgarden.extension.iastate.edu


Richard Jauron, Extension horticulturalist who coordinates the Ask The Experts column, is out of the office until Oct. 6. This week's column is a repeat of some questions answered previously.

10/2/2008

My Christmas cactus doesn’t bloom well. Why?
The Christmas cactus requires proper environmental conditions to flower. Critical factors in flower initiation are day-length and temperature. The Christmas cactus is a short-day plant. In short-day plants, the vegetation grows during the long days of summer and produces flowers when days become shorter in the fall. The Christmas cactus will not bloom properly if exposed to artificial light at night in fall. Flowers also may fail to develop if the plant is exposed to temperatures above 70 F. Night temperatures of 60 to 65 F, with slightly warmer daytime temperatures, are ideal for flower formation.

In late summer, place the Christmas cactus in a cool location that receives bright light during the day, but no artificial light at night. An unused bedroom or basement may have the proper environmental conditions. To avoid flower bud drop, do not move the plant during flower bud development. The Christmas cactus can be moved and displayed in another room when the first flowers begin to open.

How do I overwinter tuberous begonias?
Carefully dig up the tuberous begonias within a few days of a killing frost. Leave a small amount of soil around each tuber. Cut off the stems about 1 inch above the tubers. Place the tubers in a cool, dry area to cure for two to three weeks. After curing, shake off the remaining soil, then bury the tubers in dry peat moss, vermiculite, or sawdust. Store the tubers in an area with a temperature of 40 to 50 F. Do not allow the tubers to freeze.
 
What is the white stuff on the leaves of my garden plants and trees?
Powdery mildew is a common fungal disease that can occur anytime during the growing season but is especially common as fall comes. This disease causes a white, powdery growth to appear on leaves and stems of nearly any kind of plant. Some plants that are especially susceptible to powdery mildew include phlox, zinnias, lilacs and turfgrass, although nearly all plants can get this disease. Foliar diseases that occur this late in the season usually do not cause serious harm to perennial plants, as they have stored enough food already during the season. Some plant varieties resistant to powdery mildew are available. Preventing humidity in the plant canopy, such as by properly spacing plants and avoiding overhead watering, can help prevent powdery mildew. Fungicides may also be used preventively.

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Contacts :
Richard Jauron, Horticulture, (515) 294-1871, rjauron@iastate.edu
  Del Marks, Extension Communications, (515) 294-9807, delmarks@iastate.edu