Archive | June 2016

Green or brown: the choice is yours

I am not concerned that my bermudagrass lawn has turned a paler shade of brown. I know that warm-season lawns, such as bermuda-, centipede-, and zoysiagrass, whose optimum growing temperature is between 80 and 95 degrees F, have the ability to escape the dry conditions by going dormant. These grasses possess buds in their crowns and rhizomes (underground stems) that may remain alive and grow when more favorable conditions return. Tall fescue is a different matter. This cool-season grass, whose favorable growing temperatures are between 60 and 75 degrees F, cannot escape. Three or more weeks of no rain in the summer can injure or kill tall fescue.

Lawn owners who choose to have a green, lush lawn in summer must water their lawns during hot, dry spells. If you choose to water your lawn with potable water, then please use this precious resource properly.

Apply the correct amount of water:  one-inch of water per week, which wets most clay soils to a depth of 6 to 8 inches. (It takes 640 gallons of water to irrigate 1,000 square feet of lawn, and the average household in SC uses 120 to 150 gallons of water per person per day.) If you cannot apply this amount all at once because water runs off the lawn or puddles up, then apply one-half inch at a time. Allow the water to soak in before you continue irrigating. If you use a portable sprinkler, move it frequently to avoid runoff. Use a screwdriver to determine if you applied the right amount of water. About 2 to 4 hours after watering, insert the screwdriver into the ground; it’s easier to push the screwdriver into moist soil and much harder in dry soil.


Know how much water you’re applying to your lawn by calibrating your automatic sprinkler system.

For homeowners with an in-ground irrigation system, calibrate it so you know how much water you’re applying at each irrigation event. Here’s how:

  1. Place several equally-sized coffee cans or other straight-sided, flat-bottomed containers randomly throughout the area to be irrigated. For above-ground, portable, hose-end sprinklers, containers should be arranged in a straight line away from the sprinklers to the edge of the water pattern.
  2. Turn the irrigation on for 15 minutes.
  3. Turn the water off, collect the cans and pour all of the water into one of the cans used.
  4. Measure the depth of water you collected.
  5. Calculate the average depth of water by dividing the total amount of water in inches by the number of cans. For instance, if the total depth was three inches, and you used six containers, then the average depth would be 3/6, or 0.5 inches.  Multiply the average depth by four to determine the application rate in inches per hour. For example, one-half inch multiplied by four equals two inches per hour.  If you run the system for one hour, it will apply two inches of water; run it for half an hour, and it will apply one inch.  If, while the system is running, water runs off the lawn, note the time, stop the system, and let it soak in. Then turn it on again and run it until you apply the full amount of 1 inch of water.

When you operate your in-ground system, evaluate its coverage. If you’re watering the street, sidewalk, or perhaps creating a small pond in your lawn because of excessive overlap, make adjustments to ensure head-to-head coverage and an even distribution of water.

Finally, water late at night or early in the morning when dew has already formed. Use a timer to program the system to run between 11 p.m. and 2 a.m. If possible, avoid running your automatic sprinkler system between 4 a.m. and 7 a.m. out of respect for the rest of the residents of your community who like to have adequate water pressure when showering and bathing in the morning. One more thing: add a rain sensor so your neighbors won’t be talking about you when they see you watering your lawn during a frog-choking rain.

Keep in mind that watering your lawn in the summer will keep it green, but it comes with consequences. Besides having to mow that lush new growth on a regular basis, watering may encourage weed growth, stimulate disease outbreaks, and raise your water bill.

Bob Polomski © 2016     





Seek out hydrangeas for summer-flowering shrubs

Many believe that “hydrangea hysteria” erupted in 2004 with the debut of the reblooming bigleaf hydrangea, ‘Bailmer,’ known by its trade name of Endless Summer™. Since this mophead hydrangea cultivar entered the marketplace, the interest in mophead and lacecap hydrangeas skyrocketed, especially remontant or reblooming types. This frenzy to produce bigger-flowered, smaller-statured, more floriferous hydrangeas caused the number of Hydrangea macrophylla cultivars to swell to more than 300 and counting.

Hysterical hydrangea breeders diverted their attention to other species, notably the native, white-flowered smooth hydrangea (Hydrangea arborescens), which gave rise to the pink-flowered Invincibelle™ Spirit ‘NCHA1’ in 2010 and the new-and-improved Invincibelle™ Spirit II (‘NCHA2’) this past Spring.

Even the often maligned panicled hydrangea drew attention from plant breeders, who looked past its gawky, gangly stature (15 to 25 ft. high and 10 to 20 ft. wide) and homed in on its large mid-summer white panicles, preference for full sun, and tolerance to drought. Their breeding efforts led to a wide range of cultivars boasting a variety of shapes and sizes that include ‘Bulk’ (Quickfire™), ‘Phantom’, and ‘Tardiva’.

Despite these contenders, the beloved bigleaf hydrangea has no rivals. While visiting the hydrangea collection at the SC Botanic Garden this past week, I can see why. There are mopheads with cabbage-sized blooms and dainty, more refined-looking lacecaps with flattened, disk-shaped inflorescences. On many bigleaf hydrangea cultivars, their flowers are either blue or pink depending on the level of aluminum that’s available in the soil, which is dictated by the soil pH. For blue flowers on your mophead and lacecap or French hydrangeas, maintain a soil pH between 5 and 5.5. An acid soil increases the availability of aluminum, which turns the flowers blue. Apply sulfur to reduce the pH to this ideal range in late summer or when you see new growth emerging in the Spring.  To avoid having to adjust the pH, grow a blue-flowered hydrangea such as ‘All Summer Beauty’, ‘Blue Wave’, or ‘Nikko Blue’.

Pink flowers occur on bigleaf and lacecap hydrangeas with a soil pH between 6.0 and 6.5. In this pH range, aluminum becomes “tied up” or rendered unavailable in the soil and so is absent from the flowers. Use lime to increase the soil pH to this desirable range. To avoid having to maintain a particular pH, grow pink-flowering cultivars such as ‘Forever Pink’ and ‘Pia’.

Hydrangea macrophylla 'Goliath' SCBG 6_3_2016

The cultivar ‘Goliath’ is an old-timey bigleaf hydrangea from Germany that produces bouquet-sized blooms that range in color from deep pink to purplish-blue. June 8, 2015. SC Botanical Garden, Clemson, SC.

Some cultivars produce a kaleidoscope of colors, such as ‘Goliath’, which is perfect for people who aren’t sure if they want pink, blue, or blurple (a combination of pink and blue) hydrangea flowers.

If you have a landscape with high, filtered shade or a site that receives morning sun and afternoon shade, grow hydrangeas. Dr. Michael Dirr, renowned plantsman and author of Dirr’s Encyclopedia of Trees & Shrubs (Timber Press, 2011), evaluated over 250 cultivars of Hydrangea macrophylla in Athens, Georgia, and created two lists of favorites.  His “historical” favorites include ‘All Summer Beauty’ (mh = mophead), ‘Ami Pasquier (mh), ‘Blue Wave’ (lc = lace cap , Frillibet (mh), Generale Vicomtesse de Vibraye’ (mh), ‘Lanarth White’ (lc), ‘Lilacina’ (lc), ‘Mme. Emile Mouillere’ (mh), ‘Mousseline (mh), Nikko Blue’, (mh), ‘Veitchii (lc), and ‘White Wave’ (mh). His list of reblooming bigleaf hydrangeas include ‘Blushing Bride’ (mh), ‘David Ramsey (mh), ‘Decatur Blue’ (mh), Endless Summer® (mh), ‘Mini Penny’ (mh), ‘Oak Hill’ (mh), ‘Penny Mac’ (mh), and Twist-n-Shout™ (lc).

You don’t have to take his word for it. In the hydrangea collection at the SC Botanic Garden there are 39 cultivars of bigleaf hydrangeas in bloom right now, and more than 30 cultivars of mountain hydrangea, oakleaf hydrangea, smooth, and panicled hydrangea. This team of 5 hydrangeas will provide color in your garden from May to late September, and will always give you an excuse to go outside for a spell. If the heat and humidity is not to your liking, you can always enjoy them as cut flowers indoors.

Bob Polomski  © 2016

Southern magnolia comes in many shapes and sizes

When I see southern magnolias in bloom, I think of  and how the manor house at Tara would look with a pair of gargantuan specimens flanking either side of it. Thankfully, you don’t have to own a mansion to grow southern magnolias.

Granted, a southern magnolia will attain a mature height of 60 to 80 ft. with a spread of 30 to 50 ft. However, with more than 100 cultivars of southern magnolia, you can choose from a wide variety of habits, sizes, and leaf shapes. If you prefer to have flowers sooner than later, choose a cultivar rather than a seed-propagated southern magnolia–not one that


The flowers of the remontant ‘Little Gem’ magnolia appear from early May to early November.

you’ve rescued from the side of the road. It takes many years for flowering to occur on seed-grown southern magnolias—sometimes 12 to 15 years, which is why you should select vegetatively propagated clones rather than sexually-derived ones.

Here are a few of my favorites. In 1985 nurseryman Ray Bracken from Piedmont, SC began the parade of introduced cultivars with ‘Bracken’s Brown Beauty’. This compact, dense magnolia grows up to 30 ft. high and possesses dark, lustrous leaves with rusty brown lower leaf surfaces. The fragrant flowers are 5 to 6 inches in diameter.
‘Claudia Wannamaker’ is considered the queen of magnolias. It’s more vigorous than ‘Bracken’s Brown Beauty’ with a broad pyramidal form and grows 40 to 50 ft. high and 30 ft. wide.  This cultivar was introduced by Johnny Brailsford of Orangeburg, SC and named after his cousin and friend, Mrs. Claudia Wannamaker, who purchased the parent tree from a mail order nursery in 1945. This cultivar has dark green leaves with rusty brown undersides. The 8- to 12-inch wide flowers occur at an early age.
‘D.D. Blanchard’ is another tall, pyramidal southern magnolia that grows 50 feet tall and 25 to 30 feet wide, The shiny green leaves have light rusty-orange undersides. It bears 6- to 8-inch diameter, fragrant white flowers.
For narrow spaces, choose ‘Hasse’, a southern magnolia that blooms modestly but has a tight columnar habit. The parent tree is 45 to 50 ft. high and 15 to 18 ft. wide.
‘Southern Charm’ (Teddy Bear™ PP #13049), introduced by plantsman Bob Head in Seneca, SC, is the most huggable of the bunch. Although it’s a shy bloomer, the cupped leaves with felty brown undersides look and feel like a teddy bear’s ears. ‘Southern Charm’ has a dense, tight pyramidal form. The original plant is 25 feet tall and 15 feet wide.
For repeat-flowering, consider ‘Little Gem’. This selection from Warren Steed in Candor, NC grows 20 to 35 feet tall and 10 feet wide. It blooms at an early age and while the flowers are small—4 inches in diameter—they occur from May to October and into early November. Use ‘Little Gem’ as a screen or sheared hedge. Because this cultivar becomes gangly with age, prune the branches periodically to keep it looking full and dense.
Another repeat or remontant bloomer is ‘Kay Parris’, introduced by my friend Kevin Parris, a renowned magnolia hybridizer in Spartanburg, SC.  ‘Kay Parris’ has shiny leaves with wavy margins and coppery velvet undersides. The 7-inch diameter flowers occur at an early age. Expect a height of 25 to 30 feet and a width of 10 to 15 feet.
Southern magnolias are versatile, heat- and drought-tolerant southern aristocrats that can be grown in full sun to partial shade. Use them in groups, hedges, screens, and as stand-alone accent plants.
I admit, while imbibing the intoxicating fragrance of the flowers or caressing the fuzzy undersides of the leaves of the southern magnolia cultivars in the South Carolina Botanical Garden or on the Clemson University campus, I sometimes do a Scarlett O’Hara and exclaim,  “Great balls of fire!” Fortunately, no one’s around to see or hear me.
Bob Polomski  © 2016