When is the best time to prune spireas?

Spireas are deciduous, multistemmed shrubs that have been cultivated in the South since the mid-1800s.

When you prune a spirea depends on whether the flowers occur on last year’s growth or on current season’s shoots.

Spring-flowering spireas bloom on last year’s wood and should be pruned when their flowers fade. This will encourage new growth that will mature over the summer and fall and bear next year’s flowers.

Spring-blooming spireas include baby’s breath spirea, bridalwreath spirea, double Reeves spirea, and Vanhoutte spirea.

To prune them, first remove any dead or crossing branches. Then, thin out one-fifth to one-third of the oldest branches to the ground. Shorten long, lanky branches by cutting back to a side branch or bud oriented away from the center of the shrub. Finally, tip back a few of the branches to encourage branching from below the cut to create a full-looking display.

Spireas that bloom on current season’s growth should be pruned in late winter before budbreak. They include Billiard spirea, bumald spirea, and Japanese spirea and its cultivars and hybrids.

Thin out the oldest shoots at ground level to reduce overcrowding. Cut them back by two-thirds of their height or close to the ground to encourage the production of many young shoots that will bloom later in the season. To maintain an informal structural framework, stagger your pruning cuts.

During the growing season, removing the spent flower heads will promote continuous flowering, especially in Shibori Japanese spirea and bumald spirea.

spanish moss

spanish moss spartanburg

Spanish moss hanging from a branch on the campus of Spartanburg Technical College in Spartanburg, SC (USDA cold hardiness zone 8A).


Crepe mrytle in Gainsesville, FL festooned with Spanish moss. Credit: T. Polomski.

In my travels throughout the South I’ve been fascinated by the Spanish moss that drapes the branches of many trees, notably live oaks and crepe myrtles. Spanish moss (Tillandsia usneoides) belongs to a large genus of about 550, mostly epiphytic,  species in the bromeliad family (Bromeliaceae). Spanish moss (USDA zones 8-11) is native from the southern U.S. (southeast Virginia to Florida and west to Texas and Mexico).  This “air plant” lacks roots, relying almost entirely on atmospheric moisture and rainfall for sustenance. The limbs of its host tree (or telephone wire or clothesline) serve only to provide support.

The long, slender grayish-green stems and leaves of Spanish moss can reach 20 feet. They are covered are covered with dense trichomes that act like reservoirs to capture moisture and nutrients.

Three-petaled pale blue or chartreuse flowers are borne singly in the leaf axils in late spring and early summer and are pollinated by moths drawn to the musky fragrance. The small fruit capsules that result, split when ripe to release seeds that are outfitted with silky hairs.  Dispersal is mainly by wind. Reproduction also occurs  by vegetative offsets that are broken off and transported by wind or animals.

Historically, Spanish moss has been harvested and baled for use as livestock feed, garden mulch, mortar reinforcement, packing material, and mattress stuffing. It was also used  as stuffing in the seats of Henry Ford’s Model-T cars.

Visitors seeing live oak trees heavily draped with Spanish moss frequently ask if the plants are harming the tree. While Spanish moss is not a parasite in the way that mistletoe is, it can affect its host in a number of ways. First, there is the shear weight of the moss which can sometimes cause weak limbs to break. A subtler effect has been termed nutrient piracy. By intercepting wind and rain-borne dust before it can reach the ground, Spanish moss may capture nutrients that might otherwise go to feed the host plant. Such a cost is a minor one, however, and not a reason to worry about the Spanish moss that gives the Deep South so much of it’s character.



Insecticidal soap vs. dishwashing liquid

On the radio last week a caller read the label of an insecticidal soap over the phone, and wondered about the ingredient: “potassium salts of fatty acids?” The caller also wanted to know if dishwashing liquid could be used as a substitute for insecticidal soap.

I explained to the caller that these potassium salts of fatty acids are created by adding  potassium hydroxide to fatty acids obtained either from  animal fat or in plant oils. The resulting “soap salts” are most effective in controlling  soft-bodied pests such as aphids, scale and mealybug crawlers, thrips, whiteflies, and spider mites. Generally, they have little effect on beetles and other hardbodied insects (an exception being cockroaches). The soaps must come into direct contact with the pest to be effective.  The soap penetrates the outer cuticle of the insect’s body and dissolves or disrupts the cellular membranes causing dehydration and death.  Soaps can also block the spiracles or breathing pores in the insect’s body which interferes with respiration. In some cases soaps may also act as an insect growth regulator, affecting the metabolism of cells and metamorphosis.

Certain common dishwashing liquids and laundry detergents when mixed with water have also shown insecticidal and miticidal properties. When applied to an assortment of vegetable crops, Palmolive®, Dawn®, Joy®, Ivory®, and Dove®, for example, have effectively reduced populations of whitefly , aphids, and spider mites. However, dishwashing and laundry detergents are not labeled as insecticides. Although they may be insecticidal, they are chemically different from  the registered insecticidal soaps.  Furthermore they may prove phytotoxic, causing injury by dissolving the waxy cuticle of the plant’s leaf surface. I told that caller that it’s better to save these soaps or the washing of clothes and cleaning of dishes for which they were designed.

Peegee Hydrangea: you’ve come a long way baby!

One of the toughest and most adaptable of all hydrangeas that tolerates full sun, Peegee Hydrangea (Hydrangea paniculata ‘Grandiflora’) is also one of the most coarse-textured shrubs that’s difficult to incorporate into the landscape.  ‘Grandiflora’ is a deciduous large shrub or small tree that grows 15 to 25 ft. high and 10 to 20 ft. wide with a fountain-like Tardiva_hydrangeapeegee1[1]habit. Panicles of creamy-white flowers produced on current season’s growth open in June, July, and August; they age to a bronze-pink and eventually tan-brown. Since flowers occur on current season’s growth, prune as needed in late winter to early spring.

Recently plant breeders embraced this species and created more than 80 cultivars that embody the ruggedness and durability of panicle hydrangea (H. paniculata). These cultivars look nothing like your grandmother’s Pee Gee hydrangea. The come in various shapes, sizes and colors. Several outstanding cultivars that you should include in your landscape include ‘Brussels Lace’, ‘DVPpinky’ Pinky Winky®,‘Floribunda’, ‘Interhydia’ Pink Diamond(tm), ‘Kyushu’, ‘Lammetje’ Little Lamb, ‘Pee Wee’, ‘Tardiva’, ‘Unique’, ‘White Lace’, and ‘Webb’.Tardiva_hydrangeapeegee2[1]

Pawpaw: the native American fruit

Prolific pawpaw

‘Prolific’ pawpaw, Aug. 15, 2014.

When it comes to growing fruit at home, nothing could be easier or prettier than the pawpaw (Asimina triloba). This deciduous, multi-stemmed shrub or small tree can reach a height of 15 to 20 feet. Its 6 to 12 inch long, tropical-looking leaves turn yellow in the fall. Purple, one- to two-inch wide flowers appear in the spring and are pollinated by flies and beetles, undoubtedly attracted to the irresistible carrion-like scent of the blooms. Cross-pollination must occur for fruit set to occur, because an individual pawpaw is incapable of fertilizing its own flowers. They give rise to large bean-shaped fruit, which grow to about three to six inches long and one to three inches wide. The fruit has a fragrant aroma, a custard-like texture, and a banana-like almost tropical taste. Over my lifetime I’ve eaten several pawpaws and encouraged many friends and acquaintances to try them as well. In short, you either like the flavor and texture or you don’t. Recently  I discovered pawpaw’s laxative qualities, which led me to call it another common name:  poopoo.

If you’re willing to experiment with pawpaw, choose named cultivars such as Shenandoah, Susquehanna, and Rappahannock. If price is more important than quality, purchase seedling trees.

Pawpaws are difficult to transplant, so select container-grown cultivars to improve your chances at successfully establishing them in your landscape. Choose a moist, well-drained location in full sun or partial shade. Water the newly planted trees regularly during their establishment period.

pawpaw fruit cut in halfPawpaw leavesOnce pawpaws settle in, their horizontal roots create sprouts that emerge some distance from the trunk. Mowing will suppress these emerging shoots from becoming an unmanageable thicket.


History of Pomaria Nursery Exhibit


Taking Root: The Summer Brothers and the History of Pomaria Nursery. Source: http://artsandsciences.sc.edu/mckissickmuseum/taking-root-summer-brothers-and-history-pomaria-nursery

Last week I saw an exhibit at the University of South Carolina McKissick Museum in Columbia, SC titled
The contributions by the Summer Brothers at Pomaria Nursery in Pomaria, SC predated
the land grant institution and seemed to even influence the creation of the land grant system
AND extension service. It runs until Sept 20, 2014, 2nd floor, North Gallery.








Firescape your home

Wildfires are often thought of as catastrophic events that only occur out West.  Unfortunately, wildfires are a serious threat for us too.  Just drive around the Piedmont and notice the many homes, subdivisions, and communities nestled in mature forest stands.  These properties are at risk of damage in the event of a wildfire.

While it’s inconceivable to fireproof the forest, residents can safeguard their homes from wildfires by creating a “defensible space” around their homes.  A defensible space serves as the front line of defense from a wildfire.  It’s designed and managed to suppress wildfires, while giving firefighters adequate working room to defend the home.

A defensible space does not have to be devoid of vegetation.  Besides looking stark and unattractive, a barren landscape falls prey to soil erosion.  Nor should you pave every square foot of space between your home and the woods with blacktop or concrete.  It’s not only ridiculous, but impractical.

However, the defensible space should not be a tinderbox of dead limbs and other highly flammable vegetation located within 30 feet of your home.

To create an attractive, vegetated defensible space, by follow the SC Forestry Commission’s “Three R’s of Defensible Space”.

 Remove plants from the site that pose a threat to your home, particularly shrubs and trees within 100 feet of your home.  Thin out the stand to create wide spaces between the trees.  You will decrease the amount of flammable vegetation and create spaces for firebreaks.  Excellent firebreaks include open lawns, patios, driveways, walkways, and parking areas.  Attractive landscape features, such as water gardens, pools, and dry stream beds also double as barriers to stop or check fires.

 Reduce the amount of vegetation on the site, such as pruning out dead wood, removing low tree branches within 15 to 20 feet of the ground, and mowing grass—especially if it’s dry.  Keep tree limbs at least 15 feet away from chimneys, power lines, and buildings.

 Replace more highly flammable vegetation with less hazardous plant material.  For example, hardwood trees tend to be less flammable than conifers.  Consider thinning out a dense stand of shrubs or removing it completely and replacing it with an attractive, irrigated flower border.

The area of defensible space will vary depending on the kind of wild vegetation growing near the house and the steepness of the property.  However, at least 30 feet from the house keep the area clean of dead vegetation or other debris which can catch fire.  This “lean, clean, and green” cushion should contain plants that remain green and healthy during the threat of fire season.

Creating and maintaining a defensible space will improve your chances of having your home survive a wildfire.  Although you may think:  “It won’t happen to me,” let’s hope you’re right.  As my mother told me years ago, “its always better to be safe than sorry.”  Finally, I understand what she meant.

(c) Bob Polomski, 2014.