During dry spells, prioritizing is the key to a successful garden

The scant rainfall and torrid weather has taken a toll on a number of my landscape plants. Because I value potable water, I prioritize its use. Edibles and newly planted shrubs and trees, which are highly vulnerable to drought stress, earn the right to receive water from my spigot. When plants become established, meaning that they’ve regenerated enough roots to sustain themselves without supplemental irrigation, they’re watered only when the need arises.

I follow this rule regarding tree establishment: for every inch of trunk caliper (trunk diameter measured six inches above the ground), it takes at least 6 months before a tree becomes established. During the establishment period, I apply 2 to 3 gallons of water per inch trunk diameter (for example, 2 to 6 gallons for a 2-inch tree) over the root ball. After a few months of frequent irrigation, I water weekly until the plants are established.

After experiencing several dry summers that spanned more than a quarter century, I know that even established shrubs and trees may succumb to hot, dry summers, which means that you need to visit your landscape often and be on the lookout for the initial signs of water stress:  curling or crinkling leaves, yellowing or off-colored, du

Scorched magnolia

Newly planted trees, such as this southern magnolia, will experience “scorching” or browning of leaves during dry spells.

ll-looking leaves, and brown or scorched areas along the leaf margins. Obviously when you see azalea leaves that look like brown potato chips or Florida anise leaves that look like wilted leaf lettuce, the damage is already done. More severe signs of water stress include leaf drop and branch dieback. These aboveground signs are only a reflection of the unseen damage belowground, particularly to the fine, water- and mineral-absorbing roots.

Despite my hardline approach to avoid watering established plants—or at best, only when absolutely necessary, I did lose some treasured specimens this summer. Less than a week ago I cut down a seven-foot tall Atlantic white-cedar (Chamacyparis thyoides) that I planted in 2012 from a 3-gallon container. Atlantic white-cedar, native to swamps and low lying areas along the coast from Maine to Florida, was a gift from the horticulturists at Moore Farms Botanic Garden in Lake City. A photo of this conifer accompanied my July 24, 2015 post on bagworms. Sadly, I never appreciated its bright green needles and natural pyramidal habit until it turned completely brown.

Pinus pinea 7_8_2016

Italian stone pine (Pinus pinea)

While it was difficult to lose this treasured specimen and a few others, I am comforted by the gain in planting space. I have about 30 replacements that need a permanent home. In a 20-square foot area beneath a small trio of northern red, Shumard, and overcup oaks, I have a variety of potted species and cultivars that I started from seed, rooted from cuttings, or received as passalong plants. I can only hope they’ll be amendable to my tough love approach to watering.

One tree that has survived for the past four years without any supplemental irrigation is an Italian Stone pine (Pinus pinea). I purchased it in a one-gallon decorative pot right after the Christmas holiday season. This Colorado blue spruce lookalike was on the discounted table surrounded by poinsettias and rosemaries sheared into miniature Christmas trees. After two bitterly c

Pinus pinea1

New shoot growth of Pinus pinea.

old winters where temperatures dropped to 8 degrees F, this Mediterranean native is now three-and-a-half feet tall and thriving. It morphed from the cute, short-needled blue conifer into a shaggy-looking green-needled attention-getting specimen. Unlike other plants that have stopped blooming and growing, my Italian stone pine has 3 to 4 inch long expanding new shoots studded with short blue needles. I can’t wait for it to reach reproductive maturity so I can harvest its delectable pignolia or pine nuts for pesto.

Interestingly, I’ve read comments from a variety of “experts” on the internet who nearly dissuaded me from growing this Italian stone pine, which is widely planted in California and not expected to thrive east of the Mississippi, let alone in the southeast. Fortunately, Italian stone pines can’t read.

Copyright © 2016 Bob Polomski

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

St. Joseph’s lily

Although their large trumpet-shaped blooms are a familiar display during the Christmas holiday season, Dutch hybrid amaryllises (Hippeastrum hybrids) are easy-to-grow bulbs that bloom naturally outdoors from mid-May to early June. Except for gardeners in the Mountains, these amaryllises will come back for the rest of us year-after-year.

Hippeastrum SCBG

SC Botanic Garden     May 9, 2016

Growing amaryllises outdoors is fairly easy. Select a well-drained location in full or partial sun and plant the neck of the bulb where the leaves emerge about 2 to 4 inches below the soil surface. Follow-up with a 2 to 3 inch layer of mulch to conserve moisture and suppress weak growth. In subsequent years, apply a slow-release fertilizer in the spring, if necessary, when the new leaves emerge.

I grow the Dutch hybrids to impress my friends. I grow another amaryllis for me. St. Joseph’s lily (H. x johnsonii) was hybridized in the late 1700s by an English watchmaker named Arthur Johnson. The flowers are deep red with white stripes, and only a half-hand in diameter. They also have a spicy fragrance. Unlike the single-stem

St Joseph lily flower

Easley, SC             May 7, 2016

med Dutch hybrids, St. Joseph’s lily can produce as many as four stems per bulb bearing 4 to 6 flowers on each stem.

St. Joseph’s lilies thrive with little care, which is part of their appeal. They enjoy our hot unforgiving summers and are indifferent about being watered during the growing season. Every year I’ve been rewarded with dazzling red flowers from these old-timey happy-go-lucky bulbs.

Like my Mom told me years ago, newer isn’t always better. How right she was. Mother’s are never wrong.

Bob Polomski  © 2016

The secret to gardening: “It’s the soil, stupid.”

Last week I adopted some bearded irises from a friend’s garden. While it’s not the best time to move irises-when they’re in full bloom-it was necessary for a number of reasons: Gloria had to downsize her garden, she knew that bearded irises are my wife, Susan’s, favorite flower, and Mother’s Day was right around the corner.Iris flower
As I lifted the irises out of the ground, I quickly discovered that Gloria knew the secret to gardening. The rich, black soil reminded of a radio interview I conducted with Roger Swain, the man with the red suspenders” and former host of The Victory Garden on PBS. I asked Roger, “What is the secret to gardening?” Quickly he replied: “It’s the soil, stupid.”
He’s right. Oftentimes we get caught up in the beauty and performance of ornamental and edible plants without remembering that the foundation for any healthy landscape, garden, or lawn is soil. A healthy soil allows air, water, and nutrients to be absorbed by plant’s roots and lets those roots roam freely.
How do you build healthy soil?  Test the soil and add organic matter. A soil test measures the pH or acidity of the soil and the level of nutrients available for plant growth. Contact your local Clemson Extension Service office or acquire the soil sampling form online. Results from your soil test will indicate the amount of limestone or sulfur required to increase or lower the soil pH to an ideal range, which is between 5.8 and 6.5 for most vegetable and flower gardens, shrubs, trees, and lawns.  If the pH is too low or too high, nutrients can get “tied-up” in the soil and not be absorbed by the roots.  Also, maintaining an appropriate pH creates an environment that supports helpful soil-dwelling organisms, including earthworms.
The soil test results will also inform you of any minerals that may have to be added to improve the fertility levels of your soil. If your soil already has high levels of phosphorus and potassium, for example, there’s no need to purchase a fertilizer containing these two nutrients (the last two numbers on a fertilizer label).  There’s already enough in the soil to meet the plant’s needs, assuming that the soil pH is in the desirable range.
Shovel and dirt
Besides soil testing, holistic gardeners add organic matter. Organic matter improves soil tilth–its physical condition or structure. When added to clay soil, organic matter holds the clay soil particles apart and groups them into small pieces. This improved structure improves air and water movement in the soil, which translates to deeper and more extensive root development in our plants.
The kind of organic matter you mix into your soil is your choice. My grandfather liked to use rabbit and chicken manure for his vegetable and flower beds. My mother liked using fish in her rose garden.  As a child I used to bundle fish heads, tails, and other inedible parts in newspaper and then bury them around her roses.  If you’re squeamish about using these organic materials, then add compost or shredded leaves. Cover or “green manure” crops such as crimson clover or annual rye are relatively inexpensive sources of organic matter.  Sow these crops in the fall and then turn them under in the spring to enrich the soil.
Some gardener forsake organic matter for gypsum or sand, believing that either of these amendments will “loosen” their heavy clay soil.  Because our piedmont soils do not have an alkaline soil pH or high levels of sodium like the soils in the Southwest, don’t bother with gypsum.  To improve soil structure, add organic matter and maintain the right soil pH by liming.
If you’ve ever attempted to “fix” clay soil with a few handfuls of sand, you’d be pretty surprised by the outcome.  You may discover that your annual flower bed is better suited for making bricks instead of growing marigolds and petunias.  Stick with organic matter.
  I drove home with a two dozen irises in my trunk. As I glanced down at my blackened hands on the wheel, I knew that my wife will appreciate this Mother’s Day gift of passalong irises. But will the irises like my red clay?
Bob Polomski  © 2016

Lois Coker Japanese camellia: a wintertime gem rooted in South Carolina

This article, which appeared in Jan/Feb issue of The South Carolina Nurseryman (p. 4-5), was cowritten with Mary Ridgeway, Director of Kalmia Gardens of Coker College in Hartsville, SC. Since 1935 Kalmia Gardens has been open to the public free of charge from dawn until dusk, every day of the year. 

In this issue we spotlight Camellia japonica ‘Lois Coker’, which was suggested by Mary Ridgeway, Director of Kalmia Gardens of Coker College in Hartsville. It wasn’t the text in her July 17, 2014 email that bowled me over, but the attached photograph. I was immediately smitten by this perfectly sculpted flower.


‘Lois Coker’ camellia. Credit: Ione Lee.

Since the early 1980s Lois Coker Japanese camellia has accentuated the woodland plantings at Kalmia Gardens, which are home to several hundreds of other camellias species and cultivars. I wanted to know: who is Lois Coker and where did this cultivar come from?

I learned the background story of the ‘Lois Coker’ Japanese camellia from an email written by Ione Coker Lee:

“My father, Robert R. Coker, President of Coker’s Pedigreed Seed Company, discovered the white curved petals of a seedling growing under a ‘Magnolia Flora’ camellia in their backyard. It is a creamy-white camellia and bears no resemblance to the pale pink ‘Magnolia Flora’. The petal structure is entirely different as well.


‘Magnoliiflora’ on left, parent of ‘Lois Coker’ on right. Credit: Ione Lee.


“He named it for my mother Lois Coker and had it registered at the American Camellia Society. They have a ‘Lois Coker’ growing there at Massee Lane [and in Brookgreen Gardens].

“The color is usually a creamy-white, sometimes with a hint of yellow. The small, curved petals usually are in the usual radial form, but we have seen blossoms with the petals in a perfect spiral.

“Its unique structure and color make it very special. A blossom from my plant won second place in the 2013 Southeastern Flower Show in Atlanta.”

‘Lois Coker’ was registered in 1979, and its technical description belies its sublime beauty: “Reg. No. 1576: A small to medium size, white, formal double C. japonica seedling of ‘Magnoliiflora’ (Hagoromo), mid-season flowering. Originated by Robert R. Coker, Hartville [sic], South Carolina, USA. The 10 year old seedling first flowered 1976. The flower has about 50 petals and averages 9 cm across, opens flat. Plant growth is upright, dense and rapid in rate with dark green leaves, 9.5 cm long x 4.5 cm wide.”[1]

Nurseryman and owner of County Line Nursery in Byron, Georgia, grows ‘Lois Coker’ and includes the following description on his web site[2]: “This flower will cause one to do a double-take. It has a distinct yellow shadow that is hard to reproduce in a photo.”

fingerpaints 1.jpg

‘Lois Coker’ on left, ‘Magnoliiflora’ on right. Credit: Ione Lee.

I spoke to Mr. Alden about ‘Lois Coker,’ and I sensed his fondness for this cultivar. Several times he mentioned the unique yellow sheen that’s reflected by the white petals. Alden said this midseason bloomer can be expected to mature to a height of 8 to 10 ft. It can be shaped easily with judicious pruning. Cuttings root similarly as other camellias and do not require any special treatment–only time and patience.

While ‘Lois Coker’ is still winning awards at American Camellia Society shows (5 during the 2012-2013 season[3]), it’s time that this southern born-and-raised cultivar, which was the result of a happenstance discovery, goes mainstream and finds a home in southern landscapes. Some of us need the head-turning, jaw-dropping, take-me-to-my-happy-place flowers of ‘Lois Coker’ to help us cope with the dreary short days of winter.

[1]International Camellia Register (Web Camellia Register)

[2] County Line Nursery Inc., Tommy Alden, owner (http://www.countylinenursery.com/)

[3] American Camellia Yearbook 2013, American Camellia Society, 100 Massee Lane, Fort Valley, Ga.

Bob Polomski  © 2016


After its publication, I received this email from Ms. Lee:
Sent: Friday, January 02, 2015 9:19 AM
Dear Bob:  I had a call from Ryan Gainey this week telling me he had a copy of 1976 American Camelia Society bulletin in which the ‘Lois Coker’ was introduced. There is more information about its cultivation which would be of interest for your article. Apparently it took 10 years to grow from seed. Ryan Gainey is a prominent plantsman and native of Hartsville also (and a Clemson graduate).  You might want to get in touch with him if you still have time before article is published.  Happy New Year!  Ione