Extension News

Ask the ISU 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


Can I dispose of my wood ashes in the garden? 


Wood ashes contain small amounts of several plant nutrients. The nutrient content of wood ashes depends on the type of wood burned, the thoroughness of its burning, and other factors.  Generally, wood ashes contain 5 to 7 percent potash, 1 percent phosphate, and small amounts of other elements. However, the largest component of wood ashes is calcium carbonate. Calcium carbonate is a liming material. Liming materials raise the soil pH. 


The soil pH is important because it affects the availability of essential nutrients. The pH scale runs from 0 to 14. Any pH below 7.0 is acidic and any pH above 7.0 is alkaline. A pH of 7.0 is neutral. Most vegetables and perennials grow best in slightly acidic soils with a pH between 6.0 and 7.0. Plants may not perform as well in soils with a pH above 7.0 because of the reduced availability of some essential nutrients. 


Avoid applying wood ashes to garden areas with a pH above 7.0. Applying wood ashes to alkaline soils may raise the soil pH and reduce the availability of some plant nutrients. An application of 10 to 20 pounds of wood ashes per 1,000 square feet should be safe if the soil pH is below 7.0. If the soil pH in your garden is unknown, conduct a soil test to determine the pH of your soil before applying wood ashes to flower or vegetable gardens. 



My dumbcane has become tall, leggy, and unattractive. Can I salvage it?


It’s possible to renew some old houseplants by layering. Layering is a procedure used to induce roots to form on a stem while it is still attached to the parent plant. Complete or partial girdling of the plant stem interrupts the downward translocation of carbohydrates and other compounds.  The accumulation of these compounds promotes rooting at the point of injury. 


The dumbcane (Dieffenbachia) and other monocots can be layered by selecting a point 1 to 1.5 feet from the shoot tip. Make a sloping cut down toward the center of the stem. Immediately below the first cut, make an upward cut. The second cut should be approximately 1 inch below the first. The two cuts should meet in the center of the stem.


Remove the cut portion of the stem.  Dust a small amount of rooting hormone on the exposed surface. Place one or two handfuls of moist sphagnum moss around the exposed area. Wrap a piece of clear plastic around the sphagnum moss. Make sure none of the moss protrudes out the ends of the plastic wrap. Secure the plastic wrap above and below the sphagnum moss with twist ties.


Roots should appear in the sphagnum moss in 6 to 8 weeks. When a good root system has developed, cut off the stem just below the roots. Remove the twist ties and plastic and pot up the rooted stem in a well-drained potting soil. 


After the layered stem has been removed, the parent plant is usually discarded. However, it is also possible to save the original plant. Cut off the stem of the parent plant 2 to 3 inches above the soil surface. New growth will emerge from the stem and develop into a new plant. 



How do you force paperwhite narcissus?


Paperwhite narcissus are easy to force indoors. The bulbs can be forced in clear, shallow bowls (no drainage holes) or pots. 


When forcing paperwhite narcissus in bowls, partially fill the container with washed gravel or stones.  Place the bulbs on the gravel or stones. Then place additional gravel or stones around the bulbs, leaving the tips (noses) of the bulbs exposed. Add water to the bowl until it touches the bottom of the bulbs.  Maintain the water at this level throughout the forcing period. 


When forcing paperwhites in pots, partially fill the container with potting soil. Place the bulbs on the soil surface. Then add additional potting soil. When potted, the tips of the bulbs should stick above the potting soil. Water the potting soil thoroughly and then let it drain for a few minutes.  Keep the potting soil moist throughout the forcing period. 


Place the planted bulbs in a cool (45 to 50 degrees F), dark location for two to three weeks to encourage root growth. When the shoots reach a height of 3 inches, move the plants to a sunny window with a temperature of 60 to 70 degrees F. To prolong their bloom period, move the paperwhite narcissus from direct sunlight when the plants begin to flower. Paperwhite narcissus bulbs should be discarded after flowering. Paperwhites can’t be forced again and are not hardy outdoors. 



Contacts :

Richard Jauron, Horticulture, (515) 294-1871, rjauron@iastate.edu

Jean McGuire, Continuing Education and Communication Services, (515) 294-7033, jmcguire@iastate.edu

There are no photos for this week's column.