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

New Intersectional Peonies Deserve A Wow!

Posted by Hugh on October 9th, 2010

Itoh or Intersectional Hybrid Peonies (Paeonia spp.) represent a huge breakthrough in tissue culture propagation. Inherited from the tree peony is attractive dissected foliage. They are extremely winter hardy like the herbaceous types.

Plants grow two to three feet tall and wide. Strong sturdy stems support the huge flowers which size up to 10″ across. Flowers are single, semi-double or double, and available in a wide range of colors including yellow. Flowers stand upright even in heavy rain and require no staking. Bloom time is longer due to additional flowers being produced on side shoots.

Peonies are long-lived, growing in the same location for decades. They need to be properly nourished annually. Peonies prefer full to part sun (minimum of 6 hours per day), average moisture and well-drained soil which is enriched with compost or mulch annually.

Bare-root peonies should only be planted in the fall as this coincides with the time that their tubers develop most of their feeder roots. Container-grown peonies can be planted at any time. Itoh hybrids demonstrate good resistance to peony blight (Botrytis paeoniae).

Proper planting depth is very important for peonies. The crown should be planted 1½ – 2 inches below soil level. If the eyes have already begun to grow, the new growth may be set slightly above the surface.

Itoh peonies are now available through e-commerce nurseries.

Tips on Planting Peonies

Posted by Hugh on October 6th, 2010

Peonies (herbaceous types) are old-fashioned perennial favorites garnering new attention from 21st century gardeners. Their gorgeous spring flowers stand tall above the lush shrubbery growth.

This fall, plant dormant bare-root divisions of herbaceous peonies purchased from a mail-order nursery or a nearby garden center. Each division must exhibit 3 to 5 eyes (buds). Space plants a minimum of three feet apart.

Good air circulation around plants is important to prevent potential foliar and flower diseases. Avoid windy areas and shelter plants from harsh summer sun and heat in warmer climates (USDA zones 7-9).

Peonies thrive in gardens for 20 or more years. Select a sunny spot with well-drained garden soil and enrich with generous amounts of compost or well-rotted manure. A soil pH between 6 and 7 is ideal. Feed peonies with a slow release fertilizer in early spring the same as you would nourish flowering shrubs.

A critical digging step is the planting depth. Do not cover the growing eyes with more than 1 inch of soil. Setting the new plant too deep may delay or even prevent flowering. Water the newly planted peonies and cover the bed with 2-3 inches of loose ground up leaves or bark mulch. Likely, the peonies will bloom next spring and many years thereafter.

Tree peony culture will be discussed in a future blog.

Goldenrod –Set Off Some Fireworks This Fall

Posted by Hugh on October 6th, 2010

Rough-stemmed goldenrod (Solidago rugosa) grows in low woods, meadows and bogs in the eastern half of North America. ‘Fireworks’ (USDA zones 4–8) has a more compact plant habit than the species. This early blooming cultivar provides a long floral display starting in mid-August and lasting through Thanksgiving, weather permitting.

Flowers spikes are numerous and held in tight clusters on upright stems. The yellow, thread-like, cascading sprays of flowers do attracts many insect pollinators; the pollen does not cause allergies as once believed.

Goldenrods grow best in full sun to light shade. While they prefer moist, well-drained, slightly acidic soil, established plants flourish in hot, humid and dry summers.

‘Fireworks’ spreads quickly by seed and underground rhizomes and needs to be divide every 2-3 years . This upright herbaceous perennial grows 3 – 4 feet tall and 2 – 2 1/2 feet wide. Remove old flowers to encourage re-blooming. Deadhead or remove spent blooms on ‘Fireworks’ to generate added lateral floral sprays into late October and November. Removal of seed heads reduces re-seeding threat.

Clipping plants back in mid-June by one-half creates a better, well- branched plant, increases bloom head size, and reduces the need of re-staking.

Fall Planting Deadline for Pansies and Violas

Posted by Hugh on September 30th, 2010

To grow pansies successfully, follow this four- step program. Start with:

Purchasing healthy plants
Planting by mid-October or earlier
Watering in the fall and winter as needed
Fertilizing monthly through the winter and spring months.

Shop for vigorous dark green plants at local greenhouses and garden centers. Closely inspect for lots of white growing roots. Don’t buy short or spindly seedlings or those with yellowing leaves. Purchase sturdy 1801 plants (18 – 3 ½” plant cells per tray) or larger pots. Small pansies tend to be more disease susceptible. To avoid deadly root rot diseases in garden soils, move pansy/viola beds every three years.

Over much of the Southern Appalachian region (USDA zones 6-7), the completion date for planting pansies and violas is October 15th. Back up a week or two earlier if planting in gardens at higher elevations. An earlier fall planting date allows plants adequate time to root down into the warm autumn soil. Deeply rooted plants bloom heavier through the fall and winter seasons.

Large sized plants start off quickly and fall-winter flowering is better. Deeply rooted pansies and violas provide better anchorage, which prevents a chance of winter freeze heaving. Once soil temperatures drop below 45°F, plant growth slows and flower numbers decline.

There are many series of pansies and violas to choose in colors ranging from white, yellow, pink, red, and purple shades. Color patterns may be clear, blotched or picotee. Four popular pansy series are Delta®, Matrix®, Panola®, and Majestic Giant ll™. Among the popular viola series are Sorbet®, Rocky™, Penny™ and Velour™.

Prepare the garden bed or containers prior to planting. Pansies should be planted in well-drained, organically rich garden soil or container media mix. An acidic soil pH ranging between 5.2 – 5.8 avoids natural deficiencies in iron and manganese. Adding lime to pansy beds is usually unnecessary unless recommended after a soil test. Pansies thrive in full sun to partial shade. Plants grow more compact and bloom heaviest in full sun.

Franklinia – Native Tree Lost in the Wild

Posted by Hugh on September 27th, 2010

Franklinia (Franklinia alatamaha) is a wonderful small tree or large multi-trunked shrub with fragrant white camellia- like flowers. Franklinia is related to world-class flowering shrubs like camellia and stewartia. Its white 3 – 3 ½ inch camellia-like flowers appear from early August thru late September.

Franklinia is winter hardy in the Southern Appalachian region (USDA zones 6-7). Its fibrous root system prefers a well-drained, richly organic, and acidic soil much like azaleas and rhododendrons. Don’t subject to extended summer droughts or frigid drying winter winds.

Fall color is respectable with autumnal hues of red, orange and burgundy. The bark on a young tree is distinctively striped, and the main branches become fissured with age.

The species was discovered by plant explorer John Bartram and his son William growing along the Alatamaha River in southeastern Georgia in 1765. Natural populations are now extinct. All franklinia trees growing today are descendants of the Bartrams’ collected seeds.

Franklinia is a finicky grower, but very much worth the challenge. A deadly fungal root disease, Phytophthora cinnamoni, may have led to its demise in nature, is its Achilles’ heel. A 2-3 week long invasion of Japanese beetles in August may shorten individual bloom life by half.

Substitute Dwarf Cryptomeria for Yews

Posted by Hugh on September 25th, 2010

For better garden performance and different textural look around a home foundation, plant the dwarf shrub forms of Japanese cedar (Cryptomeria japonica). Dwarf cryptomeria is an excellent substitute for Japanese yews (Taxus spp.) or ‘Helleri’ hollies (Ilex crenata) which often struggle in heavy clay soils, particularly those poorly drained.

‘Globosa Nana’ (photo) has a “cookie-cutter” round, globular form, and rarely needs pruning. ‘Globosa Nana’ has bright green floiage and grows 3-6 feet tall and wide. The cultivar ‘Black Dragon’ has dark green foliage and a pyramidal growth habit (8-12 feet tall and 4-5 feet wide). Both are planted as single specimens or grouped several together They are slower growing than their taller 40-50 feet columnar counterparts.

Cryptomerias prefer well-drained, slightly acidic soil and are planted in an open sunny location. Young shrubs are remarkably shade tolerant. Their dark evergreen foliage turns a bronze to purple color during the coldest part of winter. By early spring the bright or dark green color returns to their short needles. Fertilize shrubs annually either in February or March.

Garden centers sell either balled and burlapped (b&b) or container-grown stock. Cryptomeria is best planted from February thru October. This evergreen demonstrates superior heat and drought tolerances once established in the landscape for two years.

Truly, Fall Is For Planting

Posted by Hugh on September 22nd, 2010

The seasonal theme at garden centers is “Fall is for Planting”. Plant sales are everywhere. If you have recentlypurchased a home and your budget is tight, buy yourself an early, but practicable holiday gift- a deciduous shade tree planted on the southwest side of the home. In a few short years, this tree will reward you with lower summer cooling bills.

Some good deciduous choices are red maple, green ash, tulip poplar, sawtooth oak, willow oak, and basswood. Garden centers push to reduce store inventories, saving usually 30%-40% off the listed price. I offer six basic landscape planting tips:

1. Plant only deciduous trees in the front of the home, and evergreen trees on the other three sides (pines, hemlock, etc.)
2. Dig a hole three times the diameter of the root ball
3. Plant shallow, barely covering the root ball and put no soil amendments in the hole
4. Add three inches of an organic mulch (wood chips, pine straw or compost) over the widthof the planting hole and not piled up against the trunk
5. Slowly deliver 10 gallons of water to each tree after planting
6. Do not fertilize newly planted trees and shrubs until the first day of spring.

Coppicing – Renewal Pruning for Old Rhododendrons

Posted by Hugh on September 14th, 2010

'Janet Blair' Rhododendron in Need of Coppicing

Coppicing is a form of renewal pruning because the entire shrub is lopped off to the ground. It is a drastic pruning technique primarily used on shrubs that flower and fruit on new or summer wood, those that flower in late June or later. Coppicing is renewal pruning but is so simple that gardeners is called “no brainer” pruning.

In late February, about 4-5 weeks before spring growth begins, cutback the shrub(s) leaving 3-5 inches of stubble for the new growth to emerge from the adventitious buds near the soil surface.

Coppicing invigorates old shrubs, brightens foliage color and increases fruit size. Overgrown rhododendrons, including deciduous azaleas, plus hollies, pieris and mountain laurels may be coppiced in the fall beginning in late September thru October. It eliminates disease and/or insect- riddled stems and twigs without resorting to pesticides.

Over-grown rhodies should be well-established and healthy; old shrubs in poor vigor will likely not regrow. They may be cut back severely to stumps with no leaves. Healthy plants recover, a year before the plant has much foliage and two or more years before they flower.

Hand clippers, loppers, and saws should be sharp. Do not use string mowers (weed-eaters).

Rooting Proliferations on Daylilies

Posted by Hugh on September 11th, 2010

Photo: daylily proliferations on old floral scape in late August

Proliferations are small plants which grow on the spent floral scapes of daylilies (Hemerocallus spp.). Not all daylily varieties produce proliferations. Propagating and growing proliferations is a simple way to increase the number of new daylily plants quickly.

Prune off each plantlet from the old floral scape as they form. Stick each one into a prepared ground bed. Label or tag the cultivar from which the proliferation is taken. Over the next two weeks, keep the soil/media moist. The proliferations will expand their roots into the media.

An alternative approach is to set each proliferation into its own 4-6 inch pot containing coarse sand or soil-less media or mix. Keep the media moist and grow new daylily plant into late fall. If you live in a cold winter (USDA zone 6 and colder), bury the pot to prevent serious freeze injury or grow in a protected cold frame. In areas experiencing mild winters (USDA zones 7 and warmer), transplant newly rooted plants into a ground bed before November 1st.

Plantlets should begin flowering within 18-24 months. If, in haste, you had removed the old floral scapes after spring bloom, don’t be in quite a hurry next summer.

Hardy Camellias for Southern Appalachian Region

Posted by Hugh on September 10th, 2010

'April Tryst' camellia (Spring bloomer)

Several camellias bloom reliably either in the fall and or early spring in most areas of Tennessee within USDA hardiness zone 6. In the colder higher elevations above 2000 feet, hardy camellias require some additional shelter to successfully bloom over 6 – 8 weeks. Flower colors range from white, many shades of pink, and red.

Growing camellias is very much like that of rhododendrons, but with a lot less hassle with disease and insect pests. The foliage of hardy camellias remains lustrous green year-round. Camellias relish a richly organic, well-drained, and acidic soil.

A garden site with a northeasterly exposure is a perfect nook, partially shaded from the harsh mid-day summer sun and protected from the cold drying winds of winter.

Common name: Zone 6 Hardy camellias

Botanical name: Camellia spp.

Cultivars recommended: Over 40 available; recommend starting with ‘Pink Icicle’ and ‘April Tryst’ (spring bloomer) and ‘Winter Star’ and ‘Yuletide (autumn flowering).

Type: flowering shrub

Size: 8 – 12 feet tall and 6 feet wide (see pruning)

Soil: well-drained, moist, organically amended soil; maintain a mulch depth of 2-3 inches of pine bark chips or needles.

When to plant: container plants are planted from late winter (March) through early October

Exposure: full morning sunlight, protect from afternoon heat and sunlight and drying winter winds

Watering: adequately irrigate camellias during first two years when rainfall is sparse. Established camellias demonstrate good heat and drought tolerances.

Fertilizer: nourish with an acidifying fertilizer such as Miracid™, Hollytone™ or equivalent in the months of March, May and July

When to prune: prune in very late May to reduce shrub height and broaden width
In your landscape: hardy camellias bloom with large showy flowers at a time of year when few plants do. Some exhibit exceptional evergreen foliage to rival most hollies. Be forewarned: habit-forming, you will desire to plant more camellias