What Grows There :: Hugh Conlon, Horticulturalist, Garden Advisor, and Photographer

Less Invasive Butterfly Bush Identified

Posted by Hugh on June 20th, 2017

Buddleia ‘BlueChip’ at J C Raulston Arboretum, Raleigh, NC

Butterfly bush (Buddleia) is a popular garden shrub in many areas of the U.S. Buddleia invasiveness is a serious issue in the Pacific Northwest. The Oregon Dept of Agriculture, Plant Division, has approved for sale these buddleia cultivars in the state. The approved varieties produce 2% or less viable seed, meeting Oregon’s standards for sterility.

The approved list includes: ‘Blue Chip’, ‘Asian Moon’, ‘Purple Haze’, ‘Flutterby Grande Blueberry Cobbler’, ‘Flutterby Grande Peach Cobbler’, ‘Flutterby Pink’, ‘Flutterby Petite Snow White’, ”Flutterby Grande Sweet Marmalade’, ‘Flutterby Grande Tangerine Dream’, and ‘Flutterby Grande Vanilla’. Add to the list the cultivars ‘Miss Molly’ and ‘Miss Ruby’ as personal non-invasive favorites.

Butterfly bush should be planted in full sun for sturdy stems and high floral count. Cultivars vary in size, some tall ones are placed in the rear bed, and dwarf cultivars in the front of the planting border. Flowers are sweetly fragrant upclose. Shrubs are drought tolerant once established and are tolerant of urban pollution.

New sterile hybrids are hardy to zone 5-9. They grow in average well-drained garden soil with pH range between 5.5 to 7.5. Keep plants well mulched in summer and add additional amounts in late fall for winter protection in northern areas. Shrubs are light constant feeders; choices include slow release fertilizers like Osmocote® and Nutrikote®, or monthly liquid feeding of Miracle-Gro™, Daniels™ or Espoma®.

Butterfly bushs require little pruning, but large flowering types weigh down the branches. Cut back plants to the ground in early spring as flowers are borne on new growth (wood). Pests seem to be problematic when shrub(s) are stressed out because of a poor garden site. Spider mite feedings appear to be most severe during extremely hot dry summers.

Summer Lawn Care Tips

Posted by Hugh on June 17th, 2017

Properly mowed lawn

“Summertime and the living is easy”. That’s a good adage to follow for home lawn care as well. Most lawn care chores, such as fertilizing, seeding, thatch management, and weed cleanup, should be delayed until late August through early October in most locales (USDA zones 4-7). During the heat of summer, proper mowing and irrigation are the only work necessary. Key to success is to raise the mowing height over the summer months.

Follow the one third rule. Remove no more than one-third of the grass height when mowing. Wait a few days to mow the lawn again. Scalping (close cutting) often results in a weak and weed infested lawn. If you miss a few scheduled mowings, don’t try to do it all at one time. Gradually reduce height of cut over several mowings. Don’t pick up the clippings as they contain nutrients that can be recycled as they decompose. Raked up clippings may be added them to the compost pile.

During the summer, mow cool season lawn grasses, such as Kentucky bluegrass, perennial ryegrass, and fine fescue, at heights around three inches or slightly higher. When in doubt, set the mower as high as it will go. Lawns maintained at higher heights usually develop deeper roots and dry out slower than closely mowed turf. Mulching mowers are a good investment as they are engineered to lift clippings and strike them several times before they are returned to the turf.

Cool-season lawn grasses naturally slow down and go dormant in the heat of summer. If you must irrigate, water lawns deeply at one time @ 1 to 1 1/2 inches per week. Water early in the day if at all possible. During periods of high stress, dormant lawns need only 1/4 to 1/2 inch of water every 2 to 3 weeks to keep root and crown tissue alive. Keep foot and vehicle traffic to a minimum if visible signs of drought are obvious.

Panicle Hydrangeas For Small Gardens And Containers

Posted by Hugh on June 13th, 2017

‘Bobo’ Hydrangea

‘Baby Lace’ hydrangea (Photo from Gardeners Confidence)

Panicle, PeeGee or PG hydrangeas (Hydrangea panculata) brighten up your July-August garden. They hail from China and Japan and grow almost anywhere in the U.S. (USDA hardiness zones 3 – 8). PG hydrangeas are far more reliable in northern areas (zones 3-5), than mophead hydrangeas (H. macrophylla). They flower at their best in full to partial day sunlight (6 hours or more).

PG hydrangeas are vigorous growers. Branching is upright and their deciduous foliage is coarse textured. Depending on cultivar, PG hydrangeas grow 3-15 feet, and 20-25 feet tall in tree form. Multi-branched shoots are clothe with dark green, oval shaped leaves and are topped with upright, sharply-pointed, conical, 6-8 inch long terminal flower panicles. Flowers may be a mix of both fertile and sterile florets and bloom from mid-summer into fall. PG hydrangeas are pruned any time from late fall to mid-spring. They may also be trained into a tree form.

Most gardeners are well acquainted with the popular cultivar Limelight™, the standard for excellence in PG hydrangeas. Limelight grows 6-10 feet tall (depending on amount of annual pruning provided). Its sturdy upright branched are covered with 6-8 inch long, conical shaped white flowers. Blooms make beautiful fresh or cut flower arrangements.

‘Limelight’ at NC Arboretum, Asheville, NC

Four “new” panicle hydrangeas for planting in small gardens and in containers:

Baby Lace® – petite, lacy white blooms against dark green foliage. Its smaller size of 3 by 5 feet .

Bobo™ – grows very compact size, the perfect size in small gardens and containers; large white loose flowers appear from midsummer to early fall.

‘Bombshell’ – is dwarf (compact) form with abundant star-shaped sterile flowers with elliptic sepals, dense nearly round flower panicles, and free blooming habit. It blooms earlier and longer than most other panicle hydrangeas. Flowers emerge white and slowly turn rosy pink. Strong stiff stems hold the flower panicles upright with no drooping.

Little Quickfire® – is a shorter of Quickfire, growing 3-5 feet tall with creamy spikes that turn to deep pink with red highlights on bold, red stems.

Bacterial wilt, leaf spot, rust, and mildew diseases and aphids and mites are occasional disease and insect problems. Poor site selection often enhances problems with diseases and pests.

Tidy Up These Perennials After Blooming Is Finished

Posted by Hugh on June 10th, 2017

Alliums (rhizomatous types) not responsive to deadheading

Hostas Are Best Cleaned Up After Flowering

Deadheading, the practice of removing the old spent flowers from perennials, is a way to improve a garden’s appearance and reduce overcrowding. Secondarily, many (not all) will rebloom after deadheading.

Not all perennials respond to deadheading by reblooming. Most daylilies (Hemerocallis x.), coralbells (Heuchera spp.), and hostas (Hosta spp.) are prime examples of perennials that do not rebloom. Other examples include:

Bear’s breeches (Acanthus mollis)

Bluestar (Amsonia tabernaemontana)

Lady’s mantle (Alchemilla mollis)

Rhizomatous Onions (Allium spp.)

Artemisia, wormwood (Artemisia spp.)

Astilbe, false spirea (Astilbe spp.)

Baptisia, False indigo (Baptisia spp.)

Bergenia (Bergenia cordifolia)

Heartleaf brunnera (Brunnera macrophylla)

Montbretia (Crocosmia)

Joe Pye (Eupatorium spp.)

Most kinds of fall flowering sunflowers (Helianthus spp.)

Lenten Rose or hellebore (Helleborus x orientalis)

Bearsfoot hellebore (Helleborus foetidus)

Rose mallow (Hibiscus moscheutos)

Most kinds of Irises (Iris spp.)

Ligularias (Ligularia spp.)

Monkey grass (Liriope spicata)

Catmint (Nepeta × faassenii)

Herbaceous Peony (Paeonia spp.)

Woodland phlox (Phlox divaricata)

Obedient plant (Physostegia virginiana)

Lungwort (Pulmonaria spp.)

Lambs’ ears (Stachys byzantina)

Culver’s root (Veroncastrum virginatum)

To reinforce the benefits of deadheading, the perennial bed should be weeded, mulched, fertilized, and watered. Apply a water soluble fertilizer such as Miracle-Gro™ or Schultz™. Clean up the bed of weeds and apply additional amounts of an organic mulch. If soil is dry, irrigate the bed deeply over 3 – 4 hours of overhead irrigation (equivalent of 1 ½ inches of rainfall).

Removal of the old flowers also lessens the threat of seed dispersal and future hoeing of unwanted seedlings. Many one-time bloomers, such as columbine, fall anemone (Anemone x hybrida), and gaillardia will self-seed if spent flowers are not deadheaded.

Sorting Through The Joe Pye Cultivars

Posted by Hugh on June 7th, 2017

Joe Pye Is Major Butterfly Attractor

Joe Pye weed (Eutrichum purpureum) is a native perennial commonly spotted onthe edge of farm fields in the eastern and northern U.S. (USDA hardiness zones 4 to 9). The wild species grows 5-7 feet high and 2-4 feet wide. It blooms from late July to September and is a magnet to attract bees and butterflies. Over the past two decades the “weed” has been tamed with the introduction of several shorter selections of Joe Pye. Here are the popular ones:

‘Gateway’ Joe Pye (E. purpureum ssp. maculatum) grows 5 ½ feet and offers month long show of mauve-pink domed flowers.

‘Chocolate’ Joe Pye (E. rugosa ‘Chocolate’) struts dark bronze/purple foliage and fuzzy white flowers.

‘Little Joe’ Joe Pye (E. dubium) is similar in appearance to Gateway. Plants grow 3-4 feet tall with whorls of green leaves and topped with dome-shaped heads of lavender pink flowers.

‘Baby Joe’ Joe Pye (E. dubium ‘Baby Joe’) grows only 2-3 feet tall and wide. It forms a bushy upright mound of coarse dark-green leaves, bearing large umbrella-like heads of magenta-lavender flowers in late summer.

‘Phantom’ Joe Pye (E. x ‘Phantom’) is a dwarf hybrid cultivar that grows to only 2-3 feet tall. It is a clump-forming herbaceous perennial that produces attractive and long-lasting, terminal, dome-shaped, deep pink-purple flowers atop attractive red stems, in September and October, make great cut flowers.

Hardy ageratum or mistflower (E. coelestinum) is old-fashioned 2-3 foot tall and wide perennial. It grows vigorously in old fields, meadows, and along stream banks in the South in late summer and early fall. Species is easy to grow and naturalizes freely.

Joe Pye grows just about anywhere, preferably in wet sites. Leaf edges may burn if soils become too dry. Clumps spread by underground rhizomes that are easily divided in early spring before new growth starts. Division, as well as thinning should be done frequently to ensure vigorous growth and reduce spread.Cuttings may also be rooted. Feed with slow release in early spring. Staking plants for support is generally unnecessary unless sited in too much shade. No serious insect or disease problems.

Joe Pye is utilized in perennial borders, rain gardens and mixed large containers

See Your Perennials Blooming Again

Posted by Hugh on June 4th, 2017

Red Hot Poker (Kniphofia)

Gaillardia ‘Mesa Yellow’

Deadheading is the removal of old spent flowers and stems of many perennials. Many (not all) perennials will respond and bloom a second and even a third time. Deadheading also refreshes the plant’s appearance and reduces or eliminates the threat of seed dispersal. It redirects the plant’s energy away from seed production toward root and vegetative growth.

Deadheading is one more added chore in the growing season. When perennials have finished blooming, remove the entire flower stalk. Depending on species, a perennial may bloom again 2-3 more times.

To reinforce the benefits of deadheading, the perennial bed should be weeded, mulched, fertilized, and watered. Apply a water soluble fertilizer such as Miracle-Gro™ or Schultz™. Clean up the bed, weed, and distribute additional organic mulch. If soil is dry, deeply irrigate the bed for 3 -4 hours (equivalent of 1 ½ inches of rainfall).

Many perennials will not respond to deadheading. Some specific species respond to deadheading, and others not. For most plants prune spent flowers and stems back where they originate near the plant base. New lateral shoots should appear within a few weeks and flowers within 4-5 weeks.

Deadheading Perennials (this list is not complete):

These popular perennials respond to deadheading:

Yarrow (Achillea spp.)

Hollyhock (Alcea rosea)

Columbine (Aquilegia spp.)

Butterfly weed (Asclepias tuberosa)

Hardy begonia (Begonia grandis)

Tickseeds (Coreopsis spp.)

Delphinium (Delphinium spp.)

Cheddar pink (Dianthus gratianopolitanus)

Foxglove (Digitalis spp. and cvs.)

Purple coneflower (Echinacea purpurea)

Queen of the Meadow (Filpendula ulmaria)

Blanket flower (Gaillardia x grandiflora)

Gaura (Gaura lindheimeri)

Geum (Geum spp.)

Sneezeweed (Helenium autumnale)

False sunflower (Heliopsis helianthoides)

Red hot poker (Kniphofia uvaria)

Lavender (Lavandula spp.)

Shasta daisy (Leucanthemum x superbum)

Lupines (Lupinus spp.)

Bee balm (Monarda spp.)

Penstemon (Penstemon barbatus)

Russian sage (Perovskia atriplicifolia)

Meadow phlox (Phlox maculata)

Garden phlox (Phlox paniculata)

Balloon flower (Platycodon grandiflora)

Perennial salvia (Salvia nemorosa)

Pincushion flower (Scabiosa spp.)

Indian pink (Spigelia marilandica)

Stokes’ aster (Stokesia laevis)

Spiderwort (Tradescantia x andersoniana)

Spike speedwell (Veronica spicata)

Culver’s root (Veronicastrum virginicum)

Fall In Love With Haas’ Halo® Hydrangea

Posted by Hugh on June 1st, 2017

Hydrangea ‘Haas Halo’ (photo submitted by Plants Noveau)

Closeup of huge flowers (photo from Plants Noveau)

Anyone walking through your garden will stop to see Haas Halo®) hydrangea (Hydrangea arborescens Haas Halo®). This native smooth hydrangea has intense blue-green, leathery foliage and huge pure white wide lace cap blooms (USDA hardiness zones 3-9). Flowers stand tall on stout sturdy stems. Shrub branching is upright.

This new hydrangea was found by Frederick H. Ray, former horticulture professor at Delaware Valley College in Pennsylvania. Rick selected Haas’ Halo’ from a batch of seedlings given to him by Joan Haas from her garden. Rick chose this plant because it has so many fine traits: strong, sturdy, erect stems, deep bluish-green, glossy foliage, and huge white lace-cap flowers. Flowers measure up to 14 inches across.

Lovely bluish-green foliage is thick and hearty and sets off the huge white lace cap blooms, most of which are fertile. Pollinating insects all cover ‘Haas Halo’. Ray states that very few visited the blooms of ‘White Dome’ growing nearby. The tiny fertile flowers provide nectar for beneficial insects and butterflies.

Smooth hydrangea grows best in average to medium moisture, well-drained soil in part shade although it is very adaptable to different soil types except for very dry. In the mid-South (zones 6 and 7), site it where it primarily receives morning sunlight, and weekly watering if rainfall is sparse. It tolerates more sun the northern part of its range. Blooms on new wood so you may cut it back in late winter to 1-2 feet to keep the shrub looking young and vigorous. Feed with a slow release fertilizer in early winter. Mulch to conserve soil moisture in summer.

Haas Halo is highly drought tolerant after its first year in your garden. It is beautiful planted as a specimen and just as lovely en masse along a woodland edge. Picked flowers also dry well.

Rain Barrels Save Water!

Posted by Hugh on May 29th, 2017

Artwork by Joy Stewart

Rain barrels Connected To Downspouts

The following is a guest blog from Joy Stewart, a good friend who gardens in Bristol, Tennessee. Photos taken at her garden.

Regional droughts and potential water shortages are causing people to turn to a centuries old practice of collecting rain as an alternative source of water. By collecting rainwater from your home’s roof, you have an additional supply that doesn’t tax the groundwater or shoot up your water bill.

Better yet, rainwater is oxygenated, non-chlorinated and warmer than tap water; all of these factors make it a superior source of water for your garden plants. Rain barrels are one of the simplest, cheapest means of providing water for the plants in your yard.

You will be surprised at the amount of water generated by even a brief downpour. One inch of rain on one square foot of ground surface produces .623 gallons of water. That means if you live in a smaller 1,000 square foot home and have a downspout from collects water from one quarter of the roof area, one-half inch of rain will give you almost 100 gallons of water for your rain barrel.

Rain barrels are available commercially, ranging from 50 up to 850 gallons and costing between $70 and $600. However, you can easily make your own barrel for as low as $30, depending on where you obtain your barrel. With a little searching, you can often find a used 55-gallon barrel, one formerly used to ship soda syrup, cooking oil, soap for car washes and even jalapeno peppers (although that smell is hard to remove) for about $10.

All other parts for construction are available at your local home construction supplier. A wide range of “how-to” instructions for construction and installation are available on the Internet. Once built, you can even use a good quality house paint to decorate them.

Spring – Summer Care of Herbaceous Peonies After Flowering

Posted by Hugh on May 26th, 2017

Spring flowering Peony

White herbaceous peony

Summer weather can be tough on the foliage of tree and herbaceous peonies tree (P. lactiflora). Here are some tips to ensure your peony plants will prosper for many years to come.

Keep foliage disease-free and prune off all badly infected with mildew or black spotted. Some varieties naturally shed their leaves (go dormant) early. Itoh hybrids and most hybrids maintain their foliage very late into growing season. Healthy foliage will build strong roots and increase numbers of flower buds next season.

Fertilize after flowering with granular 10-10-10 or equivalent. Usually 1-2 handfuls spread around the plant is adequate. Keep fertilizer a minimum of 6 inches away for the plant base. Mulch with an organic-based mulch such as chipped bark, composed shredded leaves, or straw to conserve soil moisture and prevent weed competition.

Deadhead your peonies, e.g.,prune off the spent flowers and seed pods. This will improve plant appearance through the long hoy summer ahead. Varieties with large blooms may have fallen over due to heavy rainfall. Many varieties will produce seeds, fall to the ground, and germinate. Eventually, seedlings grow and over time compete with the original peonies.

For foliar mildew problems, clip off all diseased or dead foliage and discard. If your area does not allow burning put it into the trash. Don’t compost diseased plant material since the spores will carry over into next year. Remove from the garden and throw in household trash or burn debris. The dead leaves are full of spores that may injure new spring foliage.

If you have additional gardening queries, contact your local Extension agent. He or she can suggest fungicides are approved in your state for peonies. Master Gardeners may also be knowledgeable area experts.

A great resource for peony information: Hollingsworth Peonies, P.O. Box 517, Hockessin, DE 19707. Telephone number: (302) 635-0140. For general information: nursery@hpeonies.com

Five Perennial Staples For Your Summer Garden

Posted by Hugh on May 23rd, 2017

‘Zagreb’ Coreopsis & ‘Becky’ Shasta daisy

Salvia ‘May Night’

If you are designing a new perennial garden, here are five proven perennials to start out with. All varieties are standout garden performers known for their long blooming period and showy flowers. Coreopsis and veronica are often utilized for edging along a sunny border. All can be planted in mixed containers.

‘Pow Wow Wild Berry’ coneflower (Echinacea purpurea ‘Pow Wow Wild Berry’) – is a distinctive cultivar of purple Coneflower. Plants form a midsized mound of coarse dark-green leaves, bearing large daisy flowers with magenta-pink petals surrounding an orange-brown central cone by midsummer. ‘Pow Wow White’ is a white flowering companion. 24 inches tall and 20 inches wide (Zones 3-9)

‘Zagreb’ Threadleaf coreopsis (Coreopsis verticillata ‘Zagreb’) – forms a spreading clump of very delicate, ferny foliage. This compact selection (12-18 inches tall and wide) bears loads of starry golden-yellow daisies, from early summer into the fall (Zones 4-9).

‘Becky’ Shasta daisy (Leucanthemum x superbum ‘Becky’) – Becky is a tall growing cultivar (36-42 inches high and 24 inches wide). Flowers are large single white daisies with a yellow eye, is excellent for cutting (Zones 4-9).

‘May Night’ Salvia (Salvia x sylvestris ‘Mainacht’) – is a medium grower (18-24 inches high and wide) with deep indigo blue flowers (Zones 3-9).

‘Royal Candles’ Spike Speedwell (Veronica spicata ‘Royal Candles’) – an outstanding upright growing speedwell with large, attractive deep-green glossy leaves and deep purple-blue flower spikes. Other veronicas available in deep purple, pink, and white; highly recommend dwarf pink flowering ‘Giles Van Hees’. Zones 4-8.

All five perennials listed here are easily to care for in full to partial sunlight (minimum 6 hours sunlight) and in average well-drained soils. Plants tolerate long dry periods after their first year in the garden. Expect 4-5 years of good flowering without the need of dividing plants. Deadheading flowers will extend blooming through the summer months. All tolerate summer heat and humidity. Flowers attract numerous bees, butterflies, and an occasional hummingbird.