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

Emerald Ash Borer Update

Posted by Hugh on October 6th, 2019

Foliage of Blue Ash (Fraxinus quadrangulata)

Emerald Ash borer (EAB) is confirmed to infest in many areas of the U.S. Emerald ash borer (Agrilus planipennis) is an exotic beetle that was discovered in southeastern Michigan near Detroit in 2002. EAB adult beetles nibble on ash foliage but cause little damage. The beetle larvae (immature stage) feed on the inner bark of ash trees, disrupting the tree’s ability to transport water and nutrients.

EAB is native to Asia and probably arrived in the U.S. around 1990 in wood packing material. Over 100 millions of ash trees have been lost in over 18 states, and in Ontario and Quebec, Canada. The cost to municipalities, property owners, nursery operators and forest products industries is in the tens of millions of dollars in the treatment and tree removal costs or lost logging production. This pest continues to spread.

EAB threatens the entire North American Fraxinus genus, unlike past invasive tree pests, which have threatened only one or a few species within a genus. Green ash (F. pennsylvania), black ash (F. nigra) and white ash (F. americana) trees are preferred hosts. Blue ash (F.
quadrangulata) displays temporary resistance to the EAB larvae but are eventually killed as well.

EAB is a very destructive insect pest in North America in terms of both the number of trees affected and the economic losses associated with the treatment and removal costs.

According to University of Tennessee plant scientists, property owners should: 1. Don’t transport firewood, even within the state. 2. Use firewood only from local sources, or purchase firewood that is certified (labelled) to be free of pests. 3. If you have moved firewood, burn all of it before leaving your campsite. 4. Watch for signs of infestation in your ash trees.

Finally, if you suspect an ash tree to be infested with EAB, call your county or city Extension office or contact a state certified arborist.

EMERALD ASH BORER

Ultra Dwarf Korean Fir

Posted by Hugh on October 1st, 2019

Korean fir (Abies koreana) is slow-growing compact fir species with a mature height between 15 to 30 feet tall and 6 to 15 feet wide. Its tiny needles are ½- to 1- inch long, green on top and two white stripes on the underside. It bears 2-3 inches long erect purple cones almost annually that mature to tan color in fall. Unlike other conifers, the cones
stand upright on the top of branches.

Dwarf cultivars of Korean firs are favorites among many conifer collectors (USDA hardiness zones 5-8). These ultra-dwarf varieties grow inches per year. To encourage a deep extensive root system, extra care (TLC) is needed the first 2-3 years after planting in the garden.

Plant in a humus-rich, acidic, well-drained soil and in a sun to partial shade garden bed. Mulch with acidic organic compost such as pine needles, shredded pine bark, or chips. Irrigate once or twice monthly during periods of drought, heat or high winds.

‘Horstmann’s Silberlocke’ is the leading Korean fir variety among conifer collectors. The German word silberlocke means “silver locks of hair”. The needles on the branches curl on the tops exposing the white underside of the needles, resulting in a frosted look. Annual growth rate is 6 – 8 inches (15 – 20 cm). Over the years, ‘Horstmann’s Silberlocke’ will develop into a small 12 feet high x 8 feet wide landscape tree. The curling needle trait is often lost as the plant age. ‘Silberlocke’ also produces purple/tan cones on young plants.

‘Cis’ grows very slowly into a round (globose) compact bun with glossy dark green needles with silvery undersides. After 10 years of growth, a mature specimen will measure 16 inches (40 cm) tall and wide.

‘Silver Pearl’ (‘Silberperle’) is a slow-growing globe-shaped cultivar with green needles above and silvery needle on underside along with a slight twist. Its very conspicuous winter buds are described as small pearls, hence its name. Ultra-dwarf annual growth rate is only 2 to 3 inches (5 – 7.5 cm) resulting in a squat 2 feet (60 cm) tall and 18 inches (45 cm) wide conical tree after 10 years.

‘Kohout’s Icebreaker’ is a superb new introduction with curled needles revealing brilliant white reverse. (8-12 x 12-18 inches tall and wide after 10 years.

Korean fir appears to be more heat tolerant than other firs, but it prefers cooler regions of the U.S. As with most firs in the South, Korean fir will often fail if too hot and will fail in wet soppy soils. In the warm humid southeastern U.S. environment, Korean fir should be grafted on Momi fir (Abies firma) rootstock. Dwarf forms make great additions to a small urban garden, a rockery, or a large container. Korean fir is rated as deer resistant.

Because of their rates of growth, super dwarfs are investments in the future. A plant with some size will likely command a premium price.

‘Early Bird’ Blooming Bulbs

Posted by Hugh on September 26th, 2019

Winter aconite (Eranthus)

Galanthus nivalis naturalized at Brent and Beck’s Bulbs in Gloucester, VA

These tiny flowering bulbs are truly early birds. Fall planted bulbs often emerge in late January and February here in the Southern Appalachian region. Once they are up and blooming, frigid temps don’t damage the flowers or plants. Instead, the winter weather causes the hardy blooms to last and last in February and March. They often emerge during an unseasonable warm period lasting 7-10 days in the 50’s days with little to no snow cover. Most common choices include snowdrops (Galanthus), winter aconite (Eranthis), glory of the snow (Chionodoxa), early crocus (Crocus spp.), and grape hyacinths (Muscari).

Bulbs should be planted in early fall. To create a showy impact, mass these early flowering beauties in patches of 10, 25 or more bulbs. Spacing will vary by which bulbs you purchase. They will thrive in dappled woodland shade to partial sunlight, tolerate practically any soil, and seem to live forever. Minor bulbs make great companions for taller bulbs. Plant some under deciduous shrubs and trees or in a bed of winter pansies. Over the years minor bulbs are truly special. Minor bulbs will perennialize and come back every year.

February Blooming Crocus

Mr. Brent Heath, of Brent and Becky’s Bulbs in Gloucester, VA, passes along some varietal recommendations. Try early flowering crocus like C. ancyrensis ‘Golden Bunch’ with tangerine yellow blossoms or the many color choices of “tommies” (C. tommasinianus). ‘Christmas Pearl’ grape hyacinths (Muscari armeniacum ‘Christmas Pearl’) bear 4-6 inch double blue flowers beginning in late February. Rijnveld’s Early Sensation’ with golden yellow opening in mid-to late January in zone 7.

Fall Garden Chores

Posted by Hugh on September 21st, 2019

February blooming edgeworthia

Fall is the perfect time to take on a few of the many spring garden chores. Here is a list of ten of the most important tasks:

Weeding– get rid of newly emerging winter annual weeds now before they flower and set seeds. Perennial weeds such as dandelions, plantains, and thistles can be sprayed and eliminated in the fall.
Gather and dispose of any diseased or insect-infested leaves in the trash. Do not add material to the compost pile.
Cut back most perennials that bloomed during the year, but leave enough stem to mark its spot next spring. Postpone cutting back ornamental grasses to enjoy their winter architecture.
Improve the garden soil by adding compost from leaf debris.
Add 1- to 2-inches of a fine bark mulch around trees, shrubs and perennials. Make sure to keep mulch from piling up around trunks or stems where moisture can build up, weaken stems and make it easier for pest and disease problems to occur.
Keep recently planted plants irrigated through the fall and winter seasons while they put down roots.
Plant more spring flowering bulbs such as daffodils, tulips, hyacinths, and muscari that will bloom next spring and many years ahead.
Create a garden diary to record successes and failures over the past year. Take lots of photos of past gardens.
Add some season extenders performs in the fall winter season such re-blooming azaleas, witchazels (Hamamelis spp.), camellias, Chinese paperbush (Edgeworthia chrysantha), winterhazels (Corylopsis spp.), lenten roses (Helleborus spp.), pansies (Viola spp.), et.al.
Add winter protection for sensitive plants and critter proof the garden with fencing and animal repellents (deer, rabbits, voles).

Types OF Tulips

Posted by Hugh on September 16th, 2019

‘Lady Jane’ species tulip

‘World’s Favorite’ Darwin Tulip

Over the centuries Dutch tulip breeders have brought to market 15 groups of the spring blooming goodies (USDA hardiness zones 3-8). The properties determining the group to which each tulip belongs are the shape of its flower, its parentage and its flowering period. Let’s take a peak at “the world of tulips”. Here is a description of 15 groups of tulips.

1 Single Early Tulips are single-flowering tulips that bloom early in the season (April). Typically, they produce fairly large, rounded flowers. The height of single earlies is around 16 inches, which is fairly short as compared to other groups. This makes them perfect for use in pots. Cultivars in this group include ‘Apricot Beauty’, ‘Flair’ and ‘Candy Prince’.

2 Double Early Tulips produce large double flowers early in the season, beginning in April. On sunny days, when the flowers in this group of tulips are wide open, they can reach a diameter of 4 inches. Their height is a bit shorter than that of the single earlies. Examples of double earlies are ‘Brownie’, ‘Foxtrot’ and ‘Orca’.

3 Triumph Tulips (crossing single early and single late tulips) possess sturdy flower stems. This is the largest group of tulips; strangely enough, they often look as if they don’t belong to the same group. Some have small rounded flowers while others have long pointed petals. Triumph tulips reach a height of about 16-20 inches and start blooming in mid-April. Tulips in this group include ‘Rem’s Favourite’, ‘Princess Irene’ and ‘Negrita’.

4 Darwin Hybrid Tulips produce large flowers with that classic tulip shape. Before the flower opens, it has the shape of an egg; once it opens, it becomes an impressive, rounded, wide-open flower. Their height of 24 inches makes them a perfect choice for borders. Darwin hybrids start blooming in mid-April and include such cultivars as ‘Pink Impression’, ‘Apeldoorn’ and ‘World Peace’.

5 Single Late Tulips produce sizable, fairly elongated flowers on tall sturdy stems. They reach a height of around 24 inches and bloom in May. Top favorites are; ‘Queen of Night’, ‘Maureen’ and ‘Temple Favourite’.

6 Lily-flowered Tulips produce slender lily-like flowers with pointed petals. Tulips in this group bloom in May and are around 20-24 inches tall. The lily-flowered group is small. Its most familiar members are ‘Fire Wings’, ‘Ballerina’ and ‘White Triumphator’.

7 Fringed Tulips (Orchid Tulips) have serrated petals. They are 16 to 24 inches tall and bloom from the end of April until far into May. ‘Mascotto, ‘Honeymoon’ and ‘Vios Con Dios’ are some of the well-known cultivars in this group.

8 Viridiflora Tulips (Green Tulip) are easily to identify for their green streaked flower petals. They bloom in May for a long period. They are 8 to 20 inches tall. ‘China Town’, ‘Artist’ and ‘Spring Green’ are popular varieties.

9 Rembrandt Tulips are not commonly found for sale. These tulips have unique feathered patterns on their petals. Some examples are ‘Rems Favourite’, ‘Zurel’, and ‘Sorbet’.

10 Parrot Tulips are single-flowering May blooming tulips that grow 16 to 24 inches tall. Huge showy flowers open wide to look like saucers are with scalloped and heavily fringed petals. Favorites include ‘Bright Parrot’ and ‘Double Flaming’.

11 Peony-flowered Tulips (Double Late Tulips) produce huge double peony-like blooms with rounded petals, some 4 inches across. Double late tulips flower in May and include ‘Angélique’, ‘Black Hero’ and ‘Orange Princess’.

12 Kaufmanniana Tulips (Waterlily Tulips) are early blooming (March). Water lily blooms grow only 4 to 10 inches tall. Three award winners are ‘Ancilla’, ‘Early Harvest’ and ‘Showwinner’.

13 Fosteriana Tulips produce slender flowers and grey-green leaves that start blooming in late March and range in height from 10 to 16 inches. ‘Orange Breeze’, ‘Purissima’ and ‘Orange Emperor’ are popular Fosteriana tulips.

14 Greggii Tulips are species tulips, available in your choice of red, yellow or white and with distinctive striped or mottled leaves. Flowers are fairly small on short stems. They bloom in April; the most familiar cultivars are ‘Fire of Love’, ‘Red Riding Hood’ and ‘Toronto’.

15 Species Tulips (Dwarf Tulips) are smaller than other tulips, ranging from 3 to 8 inches tall. Species tulips bloom earlier than most species and flowers are typically star-shaped. Some 65 species tulips are available, each varying in shape, color and fragrance. The most known species are T. turkestanica, T. sylvestris and T. tarda.

Information sources: Brent and Becky’s Bulbs in Gloucester, VA and Bulb.com

Fall Planting And Dividing Iris

Posted by Hugh on September 11th, 2019

Tall bearded (Iris x hybrida), Japanese iris (I. ensata), Siberian irises (I. sibirica) are very popular with U.S. gardeners and are favorites in my spring flower garden (USDA hardiness zones 3-9). The period from late August through mid-October is the ideal time to plant and/or divide irises. Don’t procrastinate…the earlier the better. Give plants enough time to settle in before winter arrives. In zone 5 the planting job should be completed by late September, in zone 6 by mid-October, and in zones 7-9 by early November.

Choose from hundreds of colorful varieties to add to your garden for years to come. Some tall bearded varieties are repeat-blooming in April/May and again in late summer / fall. You may want to trade varieties with neighbors and gardening friends. In the spring irises are for sale in pots at local garden shops. In the fall unsold plants are often discounted, sometimes at half price.

An iris bed should be sited in full to partial sun (5 hours minimum of direct sun) and in compost-rich, mildly acidic, well-drained soil. Plant iris shallow, barely covering the top thick roots (rhizomes). Next, cover those rhizomes lightly with a 1-2 inch layer of pine needles or shredded pine bark mulch. Feed irises a 5-10-10 or 6-10-6 fertilizer in early spring when new growth emerges. Avoid using high nitrogen products. Adding bone meal at planting time is encouraged.

Every 3-5 years, dig up and divide iris clumps. You may need to slice through their densely matted roots with a sharp ax or knife. Select primarily the vigorous clumps of rhizomes and wash off the soil with a hose. Set the individual iris fans 6-12 inches apart. When dividing in the fall, trim back iris foliage by one-half for easier handling.

Throw away old, weak rhizomes from the center of the original clump. Remove unhealthy plants and toss them in the trash bin. Do not add diseased or insect-ridden plants to the compost pile.

Peony Care in the Fall

Posted by Hugh on September 6th, 2019

October and November are ideal for fall herbaceous peony bed cleanup and to get ready for winter. Fall is the ideal time to dig up and divide old clumps of peony roots and to plant new plants.

Old yellow and brown foliage comes off easy with hand clippers. Don’t pull or yank off the foliage! Otherwise, you might damage the plant crown and below ground buds (eyes). Again, this recommendation applies to herbaceous peonies only. Tree peonies and Itoh hybrid peonies demand very different pruning; they’re pruned like shrubs and are not cut back to the ground.

Cleanup is most important as you are likely removing diseased foliage. Remove all the cutback debris from the property. Do not compost. Mildew on leaves? Powdery and downy mildew can be serious foliage to the burn pile or the dumpster. If the leaf litter is not removed, mildew spores will start attacking your plants in spring. Cleanliness does not eliminate all disease, but does reduce disease pressure. You may not need to apply pesticides next spring.

No fertilizer is needed in the fall and early winter. Wait until late winter or spring to feed your peonies. Slow-release organic fertilizers may be used in late fall as these products need time to break down in the soil.

Examples of organic fertilizers are compost, bone meal, and blood meal. Composted manure, not fresh animal manures may be applied anytime. Fresh manures, particularly chicken waste, may be too hot (ammonical nitrogen) and may burn the fleshy peony roots. Slow release fertilizers like Osmocote™ and Nutricote™ are also good nutrient sources.

If the garden soil is highly acidic, fall is an ideal time to apply lime to the soil. For alkaline soils (pH above 7), add elemental sulfur to the ground. The amount of lime or sulfur to apply depends on your soil pH. Have your garden soil tested at the county or regional Extension office. The report will inform you if lime or sulfur to apply.

Zone 6 Hardy Camellias – Plant Now!

Posted by Hugh on September 1st, 2019

More and more people gardening in zones 6 and 7 have discovered that they can successfully grow camellias. Once considered an exclusively Southern plant, many camellia varieties are very cold hardy where winter temps drop to 0 to 5°F. Their floral buds burst open with bright whites, pink and red shades, and spotted color blends.

Camellias offer beautiful garden color through the mid-South (Kentucky, Tennessee, North Carolina, and northern areas of Alabama and Georgia) and warm sections of the middle Atlantic States (Delaware, Maryland, Virginia. Planting zone 6 camellias from spring thru early September allows the root systems to grow out before the cold weather arrives.

For example, if air temperatures were to drop suddenly and plant roots were shallow in November, some flower and leaf buds will abort prematurely. A deeply-rooted evergreen camellia, one that is also adequately mulched, will succeed in a frigid winter.

Camellias grow well in partially shaded garden area where the plant(s) are sheltered from direct sun and wind. The planting site should be well-drained with an acidic, compost-rich soil. These plants prefer a moist soil, but do not over-water camellias. Add a 2-3 inches of an organic mulch around the base of each plant. Feed camellias lightly with a water soluble acidic fertilizer such as Miracle-Grow™ at planting time in late summer. Clip off any dead or broken branches.

Ten reliable zone 6 hardy camellia varieties are:

‘April Remembered’ blooming in mid-April

Spring Bloomers — ‘Pink Icicle’, ‘April Dawn’, ‘Artic Rose’, ‘April Remembered’, and ‘April Tryst’.

Fall Bloomers — ‘Winter’s Snowman’, ‘Winter’s Star’, ‘Snow Flurry’, ‘Long Island Pink’, and ‘Londontown Blush’.

Camellias are relatively deer-resistant. Most garden diseases and pests do not trouble camellias when plants are properly sited and cared for.

Wood’s White Aster Are Woodland Favorites

Posted by Hugh on August 26th, 2019

It’s late August and across the Southern Appalachian region White Wood Aster (Eurybia divaricata) are blooming. Their small daisy flowers are often seen blooming in shady woodlands in late summer. They start blooming a week or two later in the New England states and Canada (USDA hardiness zones 3-8).

In a natural woodland Wood’s Aster grows 1 ½ feet to 2 feet tall (2-3 feet in gardens). You can also identify them for their maroon (blackish) sprawling stems. The tiny long-petioled leaves are heart shaped and toothed. The smallish but plentiful white flowers measure 3/4-1 inches wide.

This trouble-free woodland aster grows in average, dry to medium, well-drained soil in part-sun, part-shade, or shade. Established plants are tolerant of dry shade. Good air circulation and an hour or two of morning sun help reduce any outbreaks of foliar diseases. Their numerous flowers attract bees and butterflies and deer don’t appear to bother white wood aster.

Wood’s white aster is available from nurseries selling native plants. Try them in rock and woodland gardens, containers and in flower beds. To increase flower numbers pinch (or mow) back plants 1-2 times in late spring to early summer to develop a compact plant habit.

This woodland aster blooms in summer’s heat and humidity and is highly tolerant to disease and pest problems. In cultivation it tends to self-sow and may become weedy.

Once established, white wood’s aster handles difficult landscape sites including clay soils and dry shade under trees and shrubs or on shaded slopes.

Editor’s note: not to be confused with Wood’s Purple Aster, aka New York aster (Symphyotrichum novi-belgii ‘Wood’s Purple’) which bears 1 to 1 ¼ inch medium violet flowers from mid-late September and grows 14-16 inch high plants.

Rose Of Sharon ‘Pillar’ Series –Floral And Architectural Splendor

Posted by Hugh on August 21st, 2019

RRose of Sharon (Hibiscus syriacus), aka althea, is a popular summer flowering shrub and small tree (USDA hardiness zones ((4)5-8). In northerly areas of the U.S., rose of Sharon may also be cultivated as a sun-loving perennial. The species grows 8-12 feet high and 6 -10 feet wide in full sun and in average garden soil. Shrubs, native from China to India, are drought tolerant once established for one year.

The Rose of Sharon (Althea) Pillar® series represents two unique columnar shrubs. Both cultivars, White Pillar® (white flowers) and ‘Purple Pillar® (lavender flowers), grow 10-16 feet tall and only 2-3 feet wide.

The Pillar althea series develop few to no side branches with little or no pruning needed. As the shrubs age, some minor spring pruning may be needed to maintain the narrow columnar form. During seasons of excessive rainfall, rose of Sharon may grow too vigorously and splay open. You may opt to clip off to hold the narrow look.

Plant in multiples of 3 or more for a formal front entrance. A lone plant standing by itself may serve as a landscape focal point. Plant in containers and grow on a sunny deck or patio. Perhaps you wish to conceal an unsightly utility box or create a short hedge or living privacy fence between you and your neighbor. Pillar altheas don’t take up lots of space width wise, perfect for a small urban garden or narrow planting spaces.

Rose of Sharon bloom on current season’s wood from late June thru August. Young plants start to bloom early. Its light purple blossoms of Purple Pillar feature deep red centers that really stand out in the garden and are stellar additions to cut flower arrangements. White Pillar bears snowy white blooms.

Their colorful flowers attract bees, butterflies, other pollinators, and an occasional hummingbird. This tough cold hardy shrub plant holds up well to heat and dry weather and deer don’t bother these shrubs. In some areas of the U.S., Japanese beetles may be an occasional pest.