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

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.

10 Winter Care Tips For Landscape Plants

Posted by Hugh on October 10th, 2015

Recently pruned roses and winter-protecting mulch

Recently pruned roses and winter-protecting leaf mold compost

Do Not Plant Chaste tree (Vitex) in Autumn in zones 6 and 7

Fall-planted perennials, shrubs and trees need some additional attention. Here are 10 basic tips to help plants get past potential winter woes:

Select balled-and-burlapped (b&b) or container-grown plants rather than bare-rooted stock. Most bare-root plants are planted in late winter or early spring when plants are still dormant.
Evergreens, particularly broad-leaved evergreens, are more susceptible to winter dryness because leaves lose more water than narrow-leaved evergreens and deciduous plants. Roots may not replace moisture loss in frozen ground.
Don’t delay planting landscape plants you found on sale at local garden centers at deep discounted prices. Early fall planting ensures good root development.
To Mulch or Not? A 2-4 inch layer of mulch can prevent wide soil temperature fluctuations. Do not mulch newly set fruit trees which may attract overwintering voles and rabbits that feed on their tender sugary bark.
Plant ground covers and shallow-rooted shrubs earlier in fall to avoid heaving out of the ground by alternate freezing and thawing. A 2-4 inch layer of mulch by late November or early December to reduce wide soil temperature fluctuations.
Particularly in northern areas, insulate rose crowns and roots with 4-6 inches of loose non-packing organic mulch such as straw or oak leaves.
Plant bulbs when there is a chill in the air or after first killing frost. In southern areas (zones 6 – 8), garden centers are lowering prices in November to make room for winter holiday inventory.
Cover the trunk of thin-barked young trees with paper wraps in late November to prevent winter frost cracks, sunscald, and deer and rodent damage; remove all wraps by early May.
In most regions prune on the “downside” of winter in March and early April. Choose a comfortable day so to avoid mistakes made in a hurry. In zone 6 marginally hardy shrubs include roses, bigleaf hydrangeas (H. macrophylla), crape myrtles, and chaste trees (Vitex spp.).
Don’t forget to move semi-tender plants in containers into an unheated garage or greenhouse for winter protection. Minimum day/night temperatures should not drop below 40 °F.

Ripening Tomatoes Off The Vine

Posted by Hugh on October 7th, 2015

Ripening Tomatoes on the vine

The threat of freezing temperatures in the fall has gardeners scrambling to harvest all green tomatoes that may be a few weeks away from regular harvest. You may opt to prepare fried green tomatoes or to ripen the fruits indoors, still a tastier alternative to store-bought tomatoes.

Pick green tomatoes that show a tinge of color at the blossom (bottom) end and feel a little softer than hard dark green fruits. Remove twigs, stems, leaves etc. that could rub or damage the skin during storage.

Inspect all fruits for decay or mold and immediately discard all bad ones. The cooler the storage area for the tomatoes, the longer the ripening process will take.

Tomatoes ripen naturally on the kitchen countertop away from direct sunlight and extremes of heat and cold; set fruits on their shoulders rather than on their blossom ends. Another popular technique is to ripen green tomatoes in a plastic or paper bag, or wrap each in newspaper and store in an enclosed plastic or cardboard box. Allow 7-14 days for ripening at home room temperature. Some long-keeping tomato varieties may take longer.

To speed the ripening process, add slices of ripe apples or bananas; ripened fruits naturally release ethylene gas. Skin color (red, pink, purple or yellow) changes occur several days earlier by this method. Peek inside the container every 2-3 days. Trucking companies often utilize ethylene gas to ripen early-harvested tomatoes, bananas, pears and other orchard grown fruits en route to the supermarket.

Green tomatoes can be fried, as in “fried green tomatoes”, or pickled, made into salsa, green tomato jam, soups, green ketchup, and added to pasta sauces.

Paint and Wrap Newly Set Peach Tree Trunks

Posted by Hugh on October 4th, 2015

The bark of young peach (Prunus persica) or nectarine (P. persica nucipersica) trees are sensitive to winter injury caused by rapid drops in daily temperatures. On a winter’s day, the sun may heat up the sapwood under the thin skinned peach bark. Research in Georgia shows that temperatures on the south side of a peach tree may reach 96 °F while the outside air temperature is only 55°F.

Sapwood thaws and refreezes, possibly injuring tissues beneath the thin bark. The south side of the trunk warms more than north side; freeze injury and bark splitting are generally worse on the south side. White latex paints offers some winter protection by reflecting heat and light away. Daily winter temperature gradients are less on the painted trunks compared to untreated.

Painting is most effective on 1-2 year old peach and nectarine trees. Apply one coat of a water-based interior white latex paint to trunk and main branches from 2 ½ feet high down to the ground. Dilute the paint at least 50% with water to allow the trunk wood to breathe. Never apply an oil-based paint to a tree trunk and branches.

One more chore: protect trunk of young 1-2 year old fruit trees against gnawing rabbits and field mice (voles). Loosely wrap chicken wire or wire mesh cloth for protection, and permit the trunk room to expand and breath. Do not wrap with plastic film or piping as this creates a winter haven for insects and other critters. Remove all protection guards once trees have started their third spring.

Photo credit: Dr. David Lockwood, Tree Fruit Specialist, University of Tennessee, Knoxville..

Foxtail Lilies Are Uniquely Different

Posted by Hugh on October 2nd, 2015

Foxtail Lilies at Chanticleer, Wayne, PA

Foxtail lilies or desert candles (Eremurus spp.) are beginning to find an audience with U.S. gardeners. Foxtail lilies are indigenous to the grasslands and semi-arid parts of Iran, Turkey, and Afghanistan (USDA hardiness zones 5–8).

Tall spires of brightly colored flowers emerge in late spring; small individual flowers are densely packed together. Each showy flower cluster can take up half of the plant’s tall stem. Flowers begin opening at the bottom of the stalk and progress upward. Colors range from white, yellow, orange and red shades.

Low mounds of grass-like leaves emerge in early spring from hardy tubers. Depending on variety, they can rise three to eight feet tall. The mound of foliage is typically covers 1-2 feet in ground width.

This herbaceous perennial thrives in full sun, and is best adapted to a moist, compost-rich, well-drained sandy soil. The Achilles heel of foxtail lilies is poor soil drainage. Adding 1-2 handfuls of Permatil® beneath each tuber at planting time prevents root rot problems and potential infestations by voles. It is exceptionally drought tolerant and requires some protection from wind.

In early autumn tubers should be planted shallowly (2 to 4 inches deep) immediately after arrival from the nursery. Do not allow tubers to dry out and do not disturb them once planted. These woody, tuberous rootstocks should be planted upon receipt 36 inches apart and never overcrowd them. Mulch the soil over winter for additional winter protection.

Should You Plant In Fall?

Posted by Hugh on September 30th, 2015

Magnolias Better Planted In Spring

Mahonia bealei better planted in spring

Should you plant in the Fall? It depends what region you live in, what month in fall, and what species you’re planting. If you live in the mid-Atlantic, coastal New England, or Southeastern U.S., fall is an excellent time to set most hardy plants. Most (not all) trees, shrubs, perennials, and spring flowering bulbs can be planted fall. Across the northern U.S. and central Canada, winter arrives early. In the southeastern U.S., you may plant safely through Thanksgiving Day.

Why plant in the fall:

Soils are warm, moderately moist, and easy to dig in.
Planting weather is mild and it is usually comfortable to work outside.
Pests, diseases, and weeds are less active in fall and little threat to new plants.
Deciduous species are dropping their foliage and gives roots time to establish before next summer. Roots actively grow in soil above 40 ºF. Winter temperatures will ensure great blooms next spring.
Apple and pear trees can be planted, but wait on cherry, plum and peaches. Protect around tree’s tender bark with chicken wire to guard against rabbit and vole injury.
An ideal time to plant spring flowering bulbs such as daffodils, tulips, hyacinths, and many more.

What NOT to plant in fall:

Shrubs like roses and bigleaf hydrangeas (H. macrophylla).
Some perennials such as sage (Salvia spp.), cranesbill (Geranium spp.), and coneflowers (Echinacea spp.).
In northerly areas (zone 5 and colder), some tree species are sometimes susceptible to an unusually severe winter. Magnolia, dogwood, tulip tree, sweet gum, red maple, birch, hawthorn, flowering cherries and plums, crape myrtles, and several oak and nut tree species like walnut and hickory.
Marginally hardy species in your region such as broad-leaf evergreens like azaleas (Rhododendron spp.), mountain laurel (Kalmia spp.), camellias, cherry laurel (Prunus laurocerasus), false holly and tea olive (Osmanthus spp.), grape holly (Mahonia spp.), English holly (Ilex aquifolium), Southern magnolia (M. grandiflora).

Prices of plants are deeply discounted in fall and sometimes worth the gamble. Adding 3-4 inches of mulch around newly set trees will trap ground heat to promote root growth and aid plant establishment. Do not fertilize newly planted trees and shrubs in the fall.