Editor’s note: Kelly R. Jackson’s Garden Corner column has a different format. He takes questions called into his phone recently at the Christian County Extension Office and answers them in the column.
Question. My asparagus fern is turning yellow. What do you think is wrong?
Answer. Asparagus ferns are among the most-drought tolerant plants we use in containers partly because they have special root structures that store water for the dry periods. Still, if your fern is neglected for too long, water stress could cause it to yellow. Likewise, excessive water can cause root and crown rots. These rots kill the plant by prevent roots from transporting water to the stems. Yellowing and stunted growth are symptoms of rot issues.
To avoid both problems, check the soil in your container occasionally by sticking your finger down to the second knuckle. If it feels dry, add water allowing it to run out of the drain holes. No drain holes? Then you are definitely at risk of root and crown rots. Sunlight can also affect the color of asparagus ferns. These plants thrive in bright light, such as a brightly lit window with morning sun.
Another possible reason for color change could have occurred before the plant was brought indoors. Asparagus ferns respond to changes in the environment, turning yellow when temperatures start to drop. If the plant was exposed to a light frost before being brought indoors, this could be causing the yellowing.
Finally, even though they have no major insect or disease problems, asparagus rust is common when the weather is cool and moist and the foliage is wet. Light yellow spots will first appear on the shoots and stems, then rust will form. It might also be interesting to note that Asparagus fern is not really even related to ferns but are related to asparagus. But don’t eat it! All parts are poisonous.
Q. Last year my evergreen shrubs were hurt severely by the winter. They have recovered this year, somewhat, but is there a way to protect them in case we have another bad winter?
A. Cold temperatures injure evergreen plants most when there are low temperatures in late spring especially following fluctuations of warm and cold periods during the winter. Evergreen shrubs keep their leaves all winter thus increasing the likelihood of browning, bleaching or dieback of foliage. The winter sun and wind cause leaves to transpire water at a time when the roots are unable to replace the water. This leads to browning of plant tissue.
Bright sunny days during the winter cause warming of tissues initiating cellular activity. Then when the sun sets, temperatures drop and foliage is injured or killed. Yew, arborvitae and hemlock are most susceptible, but winter browning can affect all evergreens. New transplants or plants with succulent, late season growth are particularly sensitive.
To minimize winter injury to evergreens, first avoid planting them on south or southwest sides of buildings or exposed areas with lots of wind. To protect what you already have, prop pine boughs or Christmas tree greens against or over evergreens to protect them from wind and sun. You can also construct a barrier of burlap either surrounding the plant or on the exposed south, southwest and windward sides. Place three or four wooden stakes around the plant allowing space between the stakes and the plant. Drape a double layer of burlap over the stakes and staple it in place. Don’t allow the burlap to touch the plants because if it gets wet and freezes it can damage the plant.
Keeping evergreens properly watered during the growing season and into fall also reduces winter injury. Continue watering in the fall although less often until the soil freezes. If you haven’t watered all year, starting in the fall will not help much. Commercially available anti-desiccant and anti-transpirant sprays have not been shown to be effective in preventing winter burn.
Kelly R. Jackson is the Christian County Extension Agent for horticulture. He can be reached at 270-886-6328 or visit Christian County Horticulture online at www.christiancountyextension.com.