TechNotes Feb. 3 – Spring Flowers, Crabgrass, Hollies in Winter

SPRING FLOWERS IN THE SOUTHEAST NEWEST. Spring-flowering bulbs like daffodils, tulips, crocus, and hyacinths are or will be flowering shortly in the southeastern United States. It is recommended the flowers be removed after flowering. The removal of the flower will prevent seed formation. After bloom, do not remove the leaves until they turn brown or at least 6 weeks after bloom. Although not flowering the plant leaves continue to photosynthesize, increasing the storage carbohydrate levels in the bulb, which will help next year’s bloom.

Failure of spring-flowering bulbs to bloom is often a result of many different factors. If the bulbs were planted in a wet area the bulbs may have rotted. A lack of bloom may also result from the bulbs being too shaded or planted too close together. Daffodils will often have a restricted or reduced bloom if planted to shallow in the soil.

CRABGRASS SEASON IN SOUTHERN U.S. Crabgrass germination is rapidly approaching in the southern United States and southern California.  When average soil temperatures reach the 50-degree mark, temperatures are approaching favorable conditions for germination.  Soil temperatures are often utilized for determining crabgrass germination.  When soil temperatures fall within the range of 52 to 58 F or 55 F at the 4-inch depth, crabgrass will begin germinating.  In areas where the turf is thin, soil temperatures will warm quicker than soils under a dense turf.  The average mean soil temperature at which initial crabgrass appearance is observed is 60 to 64 F.
 
Phenological events are also associated with crabgrass germination.  The most common plant used is forsythia.  When forsythia bloom crabgrass will start germinating.  The Eastern redbud tree is an example of a phenological timing event.  As the redbud tree approaches full bloom, crabgrass germinates.

HOLLIES SUSCEPTIBLE TO WINTER INJURY. Hollies are susceptible to winter injury if placed in exposed areas. Foliage symptoms appear brown and have a scorched look. The buds and branches are normally dead and if leaves do emerge, they often collapse. Additional symptoms include twig dieback and bark splitting.