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

Five Summer Perennials You Will Love

Posted by Hugh on November 10th, 2015

Phlox paniculata ‘Shortwood’

Echinacea x ‘Cheyenne Spirit’

In the past few years several great performing perennials have caught my eye. Some are exceptional landscape performers exhibiting long bloom period and exceptional disease resistance. All are hardy in Zones 4-9. Here are five of the best:

Echinacea Cheyenne Spirit coneflower mix (Echinacea purpurea ‘Cheyenne Spirit’) offers a spectacular floral show of many colored ray flowers from mid-summer to early fall. This hybrid purple coneflower comprises a delightful mix of bright red, orange, golden yellow, purple and white ray flowers with a large brown button center. Stems are strong and well-branched. Coneflowers attract butterflies and blooms are excellent for cutting. Deadhead (remove) faded blooms to encourage re-blooming.

‘PowWow Wild Berry’ coneflower (Echinacea purpurea) is an outstanding multi-year performer. From late spring to early fall, it produces large 3-4 inch wide deep rose-purple ray flowers with orange-brown button centers. Stems are sturdy and well-branched, 18-24 inches tall and 12-18 inches wide. Plants re-bloom without deadheading.

‘Pardon My Pink’ beebalm (M. didyma) is a self-branching, compact, 10 to 12 inches tall (and wide) beebalm or bergamont. Clear pink flowers measure 2½ to 3 inches across and attract bees, butterflies, and hummingbirds. It blooms from midsummer to late September along with dark green foliage that is highly mildew resistant.

‘Shortwood’ Garden Phlox is a garden phlox (P. paniculata) that is highly touted by Stephanie Cohen, the perennial diva herself. ‘Shortwood’ boasts full-size bright pink blooms with deeper pink eyes and are wildly fragrant. Flowers are superb for cutting, and attract lots of butterflies and hummingbirds. Plant is also highly mildew resistant.

Dazzleberry® sedum is groundcover type from sedum breeder Chris Hansen that grows only 8 inches tall and 18 inches wide. It is a strong grower with attractive dusty blue foliage. In late summer Dazzleberry is covered with clusters of vibrant raspberry colored flowers.

Echinacea purpurea ‘PowWow Wild Berry’

Fall Leaf Gathering Turns Into “Black Gold”

Posted by Hugh on November 7th, 2015

Compost in rose bed at Biltmore Estates, Asheville, NC

Compost on rose bed at Biltmore Estates, Asheville, NC

Leaf pile ready for composting

In autumn the cool crisp air paints the land with a colorful array from tree and shrub foliage. As days turn into weeks, leaves fall away and pile up on rooftops, walkways, lawns and gardens. Instead of just raking and tossing them curbside, gather and put them to good use.

Fallen leaves (and grass clippings) can be easily composted, turned into “black gold” and spread as leaf mulch over garden soils or around trees and shrubs, including roses. Leaf mold enriches the soil, locks in moisture, and protects plant crowns and roots from the frigid winter temperatures. You save money by not buying bagged mulch or compost at garden centers.

To speed the composting process, shred leaves and small twigs and branches with a mulching mower, shredder or leaf blower set on vacuum setting. Start with a thin layer of shredded leaves to compost. It decomposes rapidly, usually within a few months. Small twigs and branches decompose more rapidly. Heaping up thick heavy layers garden debris will block air and water from penetrating the pile.

Leaf mold (sometimes spelled mould) is essentially a soil conditioner. It improves soil water retention and soil structure, and creates a living habitat for beneficial organisms such as earthworms and bacteria that nourish the soil.

Distribute only a few inches of leaf mold. Thick layers of composted mulch locks in too much moisture, and smother plant roots that require well-drained soil. Roots become susceptible to rots and other fungal diseases.

The decomposition process for leaves takes at least 6-12 months. It takes very little work on the gardener’s part. To speed up decomposition, mow over the piled leaves once or twice. A few handfuls of nitrogen-rich fertilizer will speed up the rotting process. Turn the pile with garden fork or heavy rake to aerate. Throw a plastic tarp over the pile to keep leaves warm and moist.

Add leftover leaf mold to a compost bin or store remains in plastic bags for later use.

Selecting Japanese Maple Varieties For Winter Hardiness

Posted by Hugh on November 4th, 2015

Acer palmatum ‘Tamukeyama’ at NC Arboretum, Asheville, NC

Palmatum leaf type

Japanese maples (Acer palmatum) and (A. japonicum) are among the most picturesque of trees and shrubs. Their star-shaped leaves are comprised of 5-7-9 pointed lobes, depending on variety (cultivar). Trees exhibit layered branching, cascading form, lacy foliage (dissectum types), and stunning fall color. There are countless numbers of cultivars… those with green, yellow, purple, red, bronze, or variegated leaves. Tree/shrub sizes vary from 3 feet to 50 feet in height. Many cultivars are slow growing their first two years, particularly the dissectum types.

Select a variety based on its winter hardiness. Many Japanese maples are rated hardy in Zones 5 and 6 (-10 to -20 °F). You need to protect newly planted trees against winter sun scald, related to cold injury to tree bark on the south or west side.

Protect the trunk of a newly planted tree with special tree wrap, usually kraft paper or fabric, to prevent sunscald over the first two winters. The wrap swells as the trunk diameter expands; it should be totally removed after two winters. Maintain a 2-3 inch organic based mulch layer under the tree to keep roots moist and cool.

Other Japanese maples must cope with summer heat and humidity in Southern climes (Zones 7 and 8). Leaves may scorch and require shelter from midday sun. Planting them on the east or north side of the house is ideal. Green-leaf varieties tend to be more scorch resistant than red, purple, or variegated leaf types. Providing irrigation during the hot summer months is a practical step.

Rated among the cold hardiest cultivars for zone 5:

Dissectum class: Inaba Shidare, Tamukeyama, Crimson Queen, Red Dragon, and Viridis.

Palmatum class: Bloodgood, Emperor I, Sango Kaku, Atropurpureum, Osakazuki, Heffner’s Red, and Oshio Beni.

Additional species (other than A. palmatum): Acer japonicum (full moon maple) and A. aconitifolium (fernleaf maple).

Tips On Sowing Milkweed Seeds

Posted by Hugh on November 1st, 2015

Perennial Milkweeds at Chanticleer Garden in Wayne, PA

Closup of Ascelpias tuberosa flowers

Milkweed (Asclepias tuberosa), aka butterfly weeds, are tuberous rooted perennials native to the Eastern and southern U.S. (USDA hardiness zones 3 to 9). It grows in dry/rocky open woodlands, prairies, farm fields, and along roadsides. A clump of milkweed plants grow 1- 3 feet tall and spread 1 ½ feet wide. Unlike other milkweeds (Asclepias spp.), the sap is not milky.

For nearly six weeks, from late spring to early summer, 3 inch wide clusters of vibrant orange to yellow-orange flowers (umbels) cover the plant canopy. Narrow lance-shaped leaves are attached to the hairy stems. Flowers are an important nectar source for many butterfly species and leaves are a key food source for the caterpillars (larvae) of Monarch butterflies.

Butterfly weeds self-seed freely in the landscape. Prominent 3 – 6 inch long spindle-shaped seed pods break ripen, open and release multitudes of silky-tailed seeds which carry long distances by wind. Seed pods may be utilized in dried flower arrangements.

Butterfly weeds are prairie survivors. They grow in average well-drained soils in full sun. Two-year established plants are highly drought tolerant. Shoots emerge late in the spring and grow rapidly. Gardeners frequently include some in butterfly gardens, meadows, prairies, or other plantings. Do not attempt to dig up plants in the wild; they rarely survive transplanting due to their deep taproot system.

New plants are easily started from seed. Collect seed capsules from wild populations before they burst open. Dried capsules should be stored in a plastic bag. Autumn is a good time to direct sow seeds in a prepared garden bed. Most (not all) seeds will emerge by mid-summer next year, and plants will bloom for the first time in 2 – 3 years. Seeds may be sown into deep containers, but overall success is better in garden beds.

Few disease and insect problems trouble butterfly weeds when they’re grown in full sun open garden spot. Wet, poorly-drained soil leads to rot rots and eventual death. Leaves are susceptible to rust and leaf spots, particularly if the planting is too crowded or partially shaded.

‘Hello Yellow’ is a yellow-flowering milkweed cultivar. It possesses the same qualities of its orange-blooming cousin, including being a butterfly magnet.

Crocus: A Fine Start To Spring

Posted by Hugh on October 29th, 2015

Fall crocus at Atlanta Botanical Gardens

Fall blooming crocus at Atlanta Botanical Gardens

Spring flowering crocus planted around stewartia

Crocus (Crocus spp.) can be your wake-up reminder that winter is coming to an end (USDA hardiness zones 3- 8). They bloom in late winter (in the south); fall blooming varieties are also available. Bulbs (they’re actually “corms”) are available in flower colors from blue, purple, white, yellow, and mixed shades.

Choose from large and small flowered types. Six petal, cup shaped flowers stand tall above the foliage which emerges as bright green blades of grass with a center white stripe. The grassy foliage grows taller after flowers wither away.

Crocus thrive in full sun and tend to bloom earlier than those planted in partial shade. They prefer a well-drained soil with pH of 6.0 – 7.0. Crocus generally fail sown in soggy ground. Flower buds open to warming early morning sunlight, and close up in cloudy weather and in the evening. Crocus bloom and easily naturalize where winters are cold. Sow corms in mid-fall because they require 12-15 weeks planted in cold soil (35 – 45 °F) to initiate blooms.

Crocus grow 3- 8 inches high depending on variety. Sow drifts of crocus in several places around the garden, under trees, sprinkled in the lawn, in alpine and rock gardens, and in containers. Interplant crocus with short growing narcissus, hyacinths and tulips, and pansies and violas. Plant them where perennials emerge in mid-spring and crocus foliage has died back.

Crocus grow carefree for many years. They may become susceptible to virus diseases which cause leaf distortions and streaking; bloom buds fail to open. Dig up and dispose of virus infected plants to prevent spreading diseases. Crocus may be menaced by deer, chipmunks, rabbits and squirrels which eat the corms, leaves and flowers. Voles feed on the corms.

The ancient Greeks collected and dried the stigmas from autumn-flowering crocus (C. sativus) to make saffron herb used in food dishes.

Crocus may be purchased at most garden centers in the fall. For wider choice of varieties, including hard to find fall crocus, buy from a mail order supplier like Brent and Becky’s Bulbs in Gloucester, VA.

Avoid Crape Myrtle Woes In Winter

Posted by Hugh on October 25th, 2015

Lagerstromia faureii in UT Gardens in Knoxville, TN

Lagerstromia faureii at UT Gardens in Knoxville, TN

It’s no secret that in many areas with cold winters (USDA hardiness zones 6-9), hardy crape myrtle cultivars are now available. In northern areas like eastern Maryland and northern VA, crape myrtles have been prospering for two decades and more. However, there is one rule regarding winter care — “Don’t Touch”. Hold off all pruning of crape myrtles until March 1 or later.

Removal of seed capsules is ok, but not totally necessary unless you demand a litter free garden. All other pruning should wait until early spring. A common practice around shopping malls and public areas is “crape murder”; this drastic pruning should be outlawed. A landscaper lops back crape myrtles to 5-6 feet so that they don’t block the view of store signage. This practice is not recommended as it greatly limits the plant’s lifespan and branch wood hardiness.

Landscapers committing crape murder during the traditional frigid months of January and February wind up killing the plant to the ground. Likely, plants will suckered from the base and flowered the subsequent summer about a month or more later. Yes, hardy crape myrtles are tough plants despite human error.

If you must move an established crape myrtle to another location, wait until early spring. Transplanting a crape myrtle should not be necessary as replacement cost is low. It’s a lot easier to start over with a new shrub or tree form. Yes a new plant starts off smaller, but how quickly they size up.

In northeastern cities such as Boston, New York, Philadelphia, Wilmington or Baltimore crape myrtles are rated as hardy perennials. Expect an occasional winter when they will dieback to the ground. Some of the hardiest cultivars were developed at the U.S. National Arboretum. If you want to start out with just 3 or 4 cultivars, ‘Natchez’ and ‘Muskgoee’ are among the hardiest tree and ‘Acoma’ and ‘Osage’ shrub types.

New England Aster A Great Pick For Fall Garden

Posted by Hugh on October 22nd, 2015

Honey Bees Cover ‘Purple Dome’ aster

‘Purple Dome’ Aster at NC Arboretum in Asheville, NC

New England (NE) Aster (Symphyotrichum novae-angliae), aka Michaelmas Daisy, is a long-lived native perennial from the east shore west to New Mexico (USDA hardiness zones 4-8). Flowering time is from August to October. It is a favorite choice for prairie restorations, roadside plantings, and wetland sites.

This large aster species grow up to 6 feet high and stems and leaves are covered with tiny hairs. Basal leaves are alternate, entire (no teeth), and may grow to 4 inches in length. Flower colors range from lavender, blue, pink, or white.

From mid-August until early October, hundreds of blue purple to lavender flowers (to 1 ½ inches across) cover the plant canopy; ray petals surround a center burnt orange-yellow eye. Sap from crushed leaves emits a strong turpentine smell.

NE aster prefers full sun and well-drained, moist, humus-rich soil. This aster species does not survive if winter soils stay constantly wet or soggy.

For best appearance tall varieties are best pinched back once or twice by mid-summer for increased branching and more flowers. NE asters are good performers in containers. Plants should be divided in late winter or early spring to retain clump vigor every 3-4 years.

Leading NE aster cultivar is ‘Purple Dome’ with lavender blue flowers. This cultivar is very different in that plants are naturally low and bushy. Purple Dome aster grows 18-24 inches tall and up to 3 feet wide on thick and sturdy stems. Staking is rarely needed.

Diseases include various forms of fungal stem-rot and its cause is usually traced to wet soils. “Yellows disease”, caused by a virus, results in sudden wilt and death.

Bees and butterflies frequent asters and deer stay away. Late blooming asters are an important nectar source for these pollinators, especially Monarchs that are migrating to Mexico in late autumn.

Add Alliums In Your Spring Flower Garden

Posted by Hugh on October 19th, 2015

Ornamental onion in spring garden

German chives (A. lusitanicum) at Kingwood Center, Mansfield, Ohio

Ornamental alliums, members of the onion family (Amaryllidaceae), produce flowers that are uniquely ball shaped and stand atop long, graceful stems. Young children marvel about the lollipop or stargazing blooms. Depending on species, alliums come in many colors (white, yellow, pink, purple, blue), shapes (round, oval, cascading), and sizes (5 inches to 5 feet tall).

Most alliums bloom from late spring to early summer. They bridge the gap between spring bulbs and summer flowering perennials. Most grow well in containers, either planted alone or mixed with other plants. Blooms attract bees and butterflies and are terrific as cut flowers.

According to size, the short alliums include: A. flavum, A. karataviense, A. sikkimense, and A. schubertii. They fit well in rock gardens or along garden paths. For a mixed perennial border, choose intermediate 2-3 feet tall cultivars with 4-6 inch diameter spherical blooms: ‘Purple Sensation’, ‘Gladiator’, and ‘Mount Everest’.

Giant flowering types with stunning 8-10 inch diameter stargazing globes include: Stars of Persia and ‘Globemaster’. A little different are the shorter growing, egg-shaped flowering types of German chives (A. lusitanicum), drumstick alliums (A. sphaerocephalon) and fragrant Chinese chives (A. tuberosum).

Ornamental alliums are very easy to grow. Just plant them in the fall at the same time that you set tulips, daffodils and other spring flowering gems. Most alliums thrive in zones 4-8 and bloom year after year. Flowers are long-lasting both in the garden and in bouquets. When flower heads lose their color, the seed heads continue looking good for a month or more. Remove flower heads before seeds drop to avoid creating a weedy mess.

Alliums are critter-proof. Deer, voles, chipmunks and squirrels do not eat them. Harmful insects don’t bother them, and flowers are frequented by bees and butterflies for their nectar. Alliums are also disease free.

New ‘Black and Bloom’ Salvia Lovely Touch To Late Summer Garden

Posted by Hugh on October 16th, 2015

Salvia guaranitica in October garden

Late flowering tender perennial

Blue anise sage (Salvia guaranitica) is native to central South America (USDA hardiness zones 7-10). It primarily utilized as a garden annual in the U.S., but is rated a tender perennial in protected locations with winter mulch cover in zone 6. Plants exhibit a shrubby, somewhat open habit with upright branching, to 3-5 feet tall as a perennial and 2 ½ to 3 feet tall as an annual. Grow it in garden beds and in large containers.

For many years ‘Black and Blue’ has been the leading cultivar. Now introducing ‘Black and Bloom’ with thicker leaves, larger blooms and darker stems. It is heat, humidity, and drought tolerant. Through most of summer into fall, its electric blue, two-lipped, tubular, 2 inches long flowers contrast strikingly with the blackish stems. Dark green ovate leaves measure 2-5 inches in length and are paler green on the underside. The foliage emits a very mild anise odor when crushed.

Blue anise sage prefers a well-drained, rich loamy, mildly acidic pH soil, and in full to partial sun (6 hours minimum sunlight for good flowering). Cut back stems once in late spring for shorter, better branched plants. Start seeds indoors 6-8 weeks before last spring frost date or purchase plants at garden centers. Feed plants at planting time and again in mid-summer. Deadheading spent flowers will extend its bloom period.

Blue anise sage is troubled by very few serious insect or disease problems. Occasionally, sages are susceptible to downy and powdery mildew if planted in crowded spaces with poor sunlight and air circulation. Flowers attract numerous bees, butterflies, and hummingbirds. Deer usually stay away.

Landscape Trees With Messy Fruits

Posted by Hugh on October 13th, 2015

Long cones of Norway spruce (Picea abies)

Messy odorous fruits of Ginkgo

Fruit avoidance is on the mind of many property owners when purchasing trees and shrubs for their yard. Many like crabapples, mulberries and Chinese (kousa) dogwoods produce fleshy or pulpy fruits that mess lawns, walkways and stain parked cars. Many, not all, are non-native and foraging birds and other wildlife are not interested in them for their food supply.

Some plants are split into male and female, with the male flowers producing pollen and no fruits. Over the years these species are begun to dominate our yards and gardens. Ginkgo is one such example. Male ginkgoes are favored no fruits and male clones are grafted by nurseries. Ginkgoes produce foul smelling apricot looking fruits. When the ripened fruits fall on sidewalks, the area around them reeks with a terrible smell.

Kousa dogwood (Cornus kousa) is a lovely small flowering tree from China where the orangey-red fruits are consumed by monkeys. Most North Ameriican birds don’t eat them.

Crabapples (Malus spp.) hail from Eastern Europe and Asia. Small fruited forms, 5/8ths inches or less in diameter, are consumed in late fall and winter by many bird species when natural food sources are sparse. Avoid planting large fruited cultivars.

Hackberry or sugarberry (Celtis spp.) drops loads of tiny black berries to litter lawns and walkways.

Mulberry (Morus spp.) produce soft pulpy fruits that stain sidewalks.

Buckeyes (Aesculus spp.), walnuts, (Juglans spp.), oaks (Quercus spp.) are nut producing trees and shrubs.

Sycamores (Platanus spp.) and sweetgum (Liquidambar styraciflua) are the “Gumball Trees” that are a nuisance to foot traffic. Mowers with catch the dry gumball fruits and discharge them through a mower to break windows or dent metal siding.

Ginkgo or maidenhair tree (Ginkgo biloba) – female trees produce messy and odorous apricot-like fruits that will also slicken walkways, making them impassable. Many large urban centers have banned the planting of female ginkgo trees.

Norway spruce (Picea abies) and white pine (Pinus strobus) bear large cones that are litter problems on lawns and gardens.