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

Landscape Trees With Winter Interest

Posted by Hugh on December 22nd, 2016

Paper bark maple

Jacquemonti birch

Does your winter landscape look a bit shabby? This coming spring take some action by planting trees that should perk up its appearance. New tree choices should ratchet up seasonal interest, attract more bees, butterflies, and hummingbirds in the spring-summer and hungry fruit feeding birds in fall-winter.

Making smart tree choices can add four-seasons of interest to your yard. In making your shopping choices, look for such arbor features as branch architecture, bark color(s), foliage texture, flowering, and resulting seeds and fruits.

Some of my favorites of trees with winter season appeal are:

Dogwoods: flowering dogwood (Cornus florida), Chinese dogwood (C. kousa) and Japanese cornel (C. officinalis). All three offer winter or spring flowering, unique horizontal branching, fruiting, and autumn leaf color. Latter two species show off exfoliating bark in winter.

Japanese maple (Acer palmatum): including coral bark variety ‘Sango Kaku’ and yellow bark of ‘Bihou’.

Paper bark maple (Acer griseum): stunning cherry red exfoliating bark.

Trifoliate maple (Acer truncatum): nice exfoliating tan colored bark.

Birches: River birch (Betula nigra Heritage® or Dura Heat ®), Himalayan birch (B. jacquemontii), and paper birch (B. papyrifera) – all with brightly colored exfoliating bark (latter two birch species for northern areas within USDA hardiness zones 2-6).

Crabapple (Malus spp.): this spring blooming tree (hundreds of varieties), many bearing colorful fruits that invite birds to your property.

Ornamental Flowering Cherry (Prunus spp.): some varieties exhibit stunning ruby red bark color.

Hollies (Ilex spp.): female forms produce full crops of with bright red fruits. Yellow berried forms are also available.

Green Hawthorn (Crataegus viridis ‘Winter King’): bright red fruits cover branches during the winter.

Japanese Stewartia (Stewartia pseudocamellia): patchy exfoliating creamy colored inner bark.

Persian Ironwood (Parrotia persica): patchy exfoliating bark exposing a light colored inner wood.

Ginkgo (Ginkgo biloba): this ancient deciduous large landscape tree with brightly colored triangular fall foliage and grayish-brown furrowed bark.

Crape myrtles (Lagerstroemia spp.): choice of many cultivars; strong muscular bark that exfoliates to reveal colorful inner wood.

Arctic Fire™ Dogwood Brightens Up Winter Landscape

Posted by Hugh on December 19th, 2016

Intense Red Bark cut for floral arrangements

Intense Red Bark cuts for use in floral arrangements

‘Arctic Fire dogwood at Univ. of Tennessee Gardens in Knoxville

Red-twig or red osier dogwood (Cornus stolonifera) is a native shrub (USDA hardiness zones 2-7). It reaches 8 to 10 feet in height and roots sucker prolifically. It can become a chore keeping it contained in small garden spaces.

Arctic Fire™ is a superior cultivar identified by its fiery red stems and compact growth habit. Expect some minor suckering, but this cultivar is far less invasive than the species.

Arctic Fire grows 4-5 feet tall and wide. That’s almost less than half the height of other red osier shrub dogwoods. Its stunning red branches are impossible to ignore! The crimson branches are particularly striking on a frosty or snow morning.

In spring flat headed creamy white flowers appear. Arctic Fire dogwood has dark green foliage through the growing season. The pointy foliage turns purple-tinged red in autumn. In mid- to late-summer clusters of creamy white flowers form on branch tips. White berries form in late summer and attract hungry birds.

Arctic Fire grows in average well-drained soil and in partial to full-day sunlight. It is an amazingly adaptable plant. Once established it will tolerate extremely dry soil and stand up to occasional standing water. It is highly tolerant of urban air pollution.

Best stem color appears on new growth. Prune back old stems hard immediately after spring flowering to ensure an intense red twig bark display the following winter. Old branch wood that is three years and older should be removed at or near ground level. In early spring apply a slow release fertilizer such as Osmocote™ or Nutrikote™ specialized for trees and shrubs. Follow the label rate of application. Deer usually stay away from red osier dogwoods.

Utilize it as a perennial or shrub borders. Winter branches and spring flowers may be cut for flower arrangements.

Saving Heirloom Seeds

Posted by Hugh on December 16th, 2016

Dogwood fruits (called cornels)

Seed heads of Goldenrod (Solidago)

At the end of each growing season, you may choose to collect seeds from favorite flowering annuals and vegetables to holdover and plant in next year’s garden. Some may be heirloom varieties that you have saved for many years because you like their productivity or flavor.

Note: these seeds should not be “hybrids”. Hybrids represent a cross between two specific parent plants resulting in such as hybrid Big Boy™ tomato, Spirit™ Hybrid pumpkin, or hybrid Wave™ petunias. Saved seeds of hybrid vegetables and flowers rarely come back “true.” Progeny won’t yield back the exact flowers, fruits, or yields in the next crop. Their resistance to diseases may also be lost.

In late fall nursery producers collect dogwood, maple, and other seeds from landscape trees or shrubs. They will clean and sow seeds in a prepared planting bed. Dormant seeds will be chilled (called “vernalization”) in the ground over winter and germinate next spring. Eventually, seedlings may become new woody plants or serve as rootstock upon which specific cultivars (varieties) of dogwood or maple are grafted or budded onto.

If you are saving wildflower seeds to re-establish a meadow next spring, harvest them in fall. Seeds may be chilled in a refrigerator (for spring planting) or sow directly into a newly prepared garden bed in the fall.

To save non-hybrid seeds:
• Start by inspecting seed heads a few weeks prior to the seeds shattering. Seedheads should appear dry. Pulpy seeds (fruits) will have colored up and are starting to shrivel. Be watchful that seeds don’t blow away. If you delay a day or two too long, they may be gone.
• Big seeds are easier to save than tiny seeds. Indoors, spread the seeds out over sheets of newspaper, paper towel, or a screen mesh.
• Separate the seeds from any chaff. Small seeds may dry in 7 to 10 days. Larger seeds may take two weeks or longer.
• Store seeds in a zipper-type plastic freezer bag or in a glass jar with a screw-on lid. Baby-food and Mason jars are also excellent for seed storage. Close the lids securely. Label containers with cultivar name of each plant (flower) and record collection date of all seeds to be stored. Place the containers in either a refrigerator or freezer. You may also store them in an unheated garage, but wildly fluctuating temperatures could damage seeds.

Small Southern Magnolia Cultivars

Posted by Hugh on December 13th, 2016

‘Kay Parris’ Southern Magnolia

Screen of Southern Magnolia

Southern Magnolia (Magnolia grandiflora) is one of nature’s magnificent landscape trees (USDA hardiness zones 6-9). This reliable large tree, native to the Southern U.S., is at home in well-drained clay soils and hot summers. The species typically grows to 60-80 feet tall with a pyramidal (young) to a rounded crown (mature tree). It is not uncommon to see the species growing in Boston, New York City and other major urban centers.

Short, more compact, cultivars are available for smaller landscapes (see below). Southern magnolias are cherished for their attractive dark green evergreen foliage and showy fragrant flowers. Large 5 to 6 inch pure white goblet shaped flowers appear sporadically from mid-spring thru late-summer. Trees shed older leaves in spring as new ones emerge.

Southern magnolia thrives in a moist, humus-rich, mildly acidic soil and in full sun. Young trees are shade tolerant, but do not flower as well, and will require more sunlight as it ages. Roots are shallow and spread widely into lawn areas. Trees tolerate short intervals in wet soggy soils without injury. Once established, within a two year span, select cultivars are highly tolerant of long dry summer spells. On occasion boughs get weighed down and snap off under heavy snow and ice loads.

Leading compact cultivars:

‘Kay Parris’ – this beautiful compact form has caught the eye of both professional landscapers and gardeners. It has extremely glossy, bright green leaves with dark red russet fuzzy underneath, and long flowering season.

‘Hasse’- grows 35-45 feet high and 18-20 feet wide after 30 years. Young trees exhibit tight narrow branching, glossy dark green leaves, and dusty red underneath.

‘Alta’ is a sister seedling of ‘Hasse’ and has a definitive columnar form. Alta is more slow growing to 20 feet tall and 9 feet wide in 10 years. Branches hold their upright “stovepipe” form for many years. Dark green glossy leaves are rusty underneath.

‘Little Gem’ is an old and very popular cultivar. It can be trained into compact tree but grows naturally shrub-like to 30 to 35 feet height. Glossy green leaves are bronze-brown underneath.

Crape Myrtles Exhibit Beautiful Bark In Winter

Posted by Hugh on December 10th, 2016

Light colored bark of ‘Lipan’

The flowers of crape myrtles are a wonderful floral treat in the summer months, several exhibit gorgeous exfoliating bark. Some also show off autumn foliage colors. Here are the best ten species and cultivars of crape myrtles noted for their exfoliating bark.

Lagerstroemia hybrids (L. indica x L. fauriei)

Hopi – 8-10 feet semi-dwarf shrub; gray brown exfoliating bark; medium pink flowers.

‘Tuskegee’ crape myrtle at Daniel Stowe Botanical Garden in Gastonia, NC

Tonto –8-10 feet multi-stemmed large shrub; light cream bark; dark fuchsia flowers.

Acoma –11-15 feet high shrub-like habit; cream white bark; clear white flowers

Lipan – 11-15 feet high multi-stem small tree; near white bark; medium lavender flowers.

Osage –11-15 feet high shrub-like habit; chestnut-brown bark; clear pink flowers

Apalachee – 16-20 feet height; cinnamon -brown bark; lavender blossoms

Miami –21-25 feet; dark brown inner bark; dark pink flowers

Tuscarora – 21-25 feet tall; light brown exfoliating bark and deep coral pink flowers.

Muskogee – 30 feet tall; light gray-brown bark; light lavender flowers

Natchez – 30-33 feet high; dull white flowers; deep cinnamon-brown bark

Select Acoma or Lipan for their near white to cream colored bark, an alternative in the South (USDA hardiness zones 7 thru 9) where white bark birches (Betula spp.) do not thrive in warmer environs.

L. fauriei selections:

‘Townhouse’ – 40 foot high; small snowy white flowers; dark chocolate bark.

‘Fantasy’ – 50 feet high; small snowy white flowers; flaking cinnamon brown bark.

Best locations to plant crape myrtles are in full sun and in moist rich soils. They tolerate poor soils if they’re adequately drained. From the list above, select the cultivar(s) that will fit the landscape space. In urban areas plant them along boulevards, in parking lots, and in small pavement cutouts. If soil area is limited, provided with irrigation until plant (s) are well established. They tolerate clay and alkaline soil well.

Insect pests are few, but some cultivars of crape myrtles are susceptible to powdery mildew damage, especially in shady or areas with poor air circulation. Many USDA cultivars are resistant to powdery mildew and aphids. Crape myrtle scale is a new insect pest that is slowly moving northward from southern areas of the U.S.

Photoperiodism – Short Day/Long Day Plants

Posted by Hugh on December 7th, 2016

‘Prestige’ poinsettias ready for Christmas sales

Fall mums at Longwood Gardens (photo by Jane Conlon)

“Photoperiodism” or daylength is responsible for triggering flowering in numerous plants. Some examples of short day plants are poinsettias (Euphorbia pulcherrima), fall mums (Dendranthemum spp.), asters (Symphyotrichum spp.), Thanksgiving (Schlumbergera truncata), Christmas (S. bridgesii) cacti, Kalanchoes (Kalanchoe spp.) and Salvias (Salvia spp.).

“Photoperiodism” is the amount of light and darkness a plant is exposed to. The amount of uninterrupted darkness on most types of plants bloom is at least 14 hours long nights (dark) and daylight periods are between 8-10 hours for 6 weeks. Streetlights or indoor lighting may disrupt the dark period and greenhouse growers may need to be covered the crop each night.

Another way of defining photoperiodism is short day plants require a longer period of darkness daily. Short-day plants flower only when daylengths are less than 12 hours per day. The length of dark period is most crucial.

Mums, poinsettias and holiday cacti need less than 12 hours of light daily over six continuous weeks from late spring and early summer. Note: holiday cacti will also initiate flower buds when exposed to cool night temperatures between 50-55°F over 4 weeks. However, no flowers will form if night temperatures are consistently above 68°F regardless of light length.

You may also stimulate bloom in long day plants such as lilies, roses, petunias and spinach if daylengths surpass 12 hours. Simply set these plant under lights for a few hours daily beyond natural outdoor daylength for 3-4 weeks. Here, you’re interrupting their night (dark) period.

In a third category are the “day-neutral” plants. They do not depend upon the amount of dark or daylight hours. When these plants reach a certain age or maturity, flower buds are initiated, flowering happens, and later set seeds or fruits. Sunflowers (Helianthus annuus) and tomato are examples of day neutral plants. Strawberries may be classified as either “everbearers”, “June bearers” or “day neutral”, depending on variety.

Key Points About Poinsettias

Posted by Hugh on December 4th, 2016

Healthy closed flowers will look good over the holidays

New Poinsettia Variety ‘Ice Crystal’

The beautiful poinsettia (Euphorbia pulcherrima) has become a symbol of the Christmas and winter holidays. The showy colorful bracts, that most people think are the flowers, are actually modified leaves. The tiny “true” flowers are in the center of the bracts.

Joel R. Poinsett introduced the poinsettia plant to the United States from Mexico. Poinsett was a botanist, physician and the first U.S. Ambassador to Mexico. In Mexico poinsettia grows as a 10-15 feet tall perennial shrub. In the U.S. plants thrive in Florida and Southern California gardens (zone 9). Here, they’re sometimes planted in late summer where the vivid bract colors add pizzazz to the fall-winter landscape. Plants hold up to night temperatures in the upper 30’s.

A member of the botanical family Euphorbiaceae, leaves and stems ooze milky sap. However, no parts of a poinsettia plant are poisonous. Some people and pets may develop a skin irritation from the sap.

Tips on purchasing: before purchasing the true flowers should be fully formed and tightly closed. If the yellow pollen sacs have shed or the flowers have dried out, do not purchase. Once the flowers start to age, the colorful bracts soon decline. The plant may look poorly on Christmas Day.

Care In The Home: place your poinsettia near a sunny window that faces south or east and room temperatures are between 65 to 75 °F. Poinsettias thrive in a well-drained soilless media (potting mix). Check for dry soil every few days and water thoroughly; excess water should flow freely out the drainage hole in the container. Never leave a poinsettia standing in water for over one-half day as it may cause root injury. Feed the plant every 2-3 weeks with a water soluble fertilizer @ one-half the rate of package directions through the winter months. Your poinsettia may still look beautiful on the first day of spring.

There are more than 100 varieties of poinsettias available today. Varieties come in lots of colors from traditional red, white, pink, burgundy, marbled and speckled.

Purchasing A Cut Christmas Tree

Posted by Hugh on December 1st, 2016

Cut Christmas trees for sale

Christmas Tree Farm in SW Virginia

Around the holidays lots of people head out to local Christmas farms to purchase a tree. Local farms offer the best freshly cut trees that should last 3 or more weeks inside your home. Trees for sale in urban lots may have been harvested between 1-4 weeks earlier and shipped to your vicinity.

A cut Christmas tree should last longer if you choose one that’s fresh (branches are pliable and needles are not dried out). Keep the butt end of the trunk immersed in water until you are ready to bring the tree indoors for decorating.

Here are some tips in purchasing a tree:
1. Test for freshness by holding a branch between your thumb and fingers and pulling lightly toward you. If very few or no needles fall off, the tree is fresh. If the end of a branch bends easily, that’s also a sign of freshness. If you observe some yellowing, browning, or falling of interior needles, that’s okay. But, if you pick up a tree a few inches and slam it back down, lots of needles shouldn’t wind up on the ground.
2. Most tree lots will usually offer to cut the trunk of the tree for you. This allows for fast water uptake. You need to get the tree home and into water quickly.
3. If you’re not ready to take your cut tree indoors, set it in a bucket of water and keep it on a porch or in the garage—where it’s cool and sheltered from wind and sun.
4. Freshly cut 2-3 inch off the bottom (butt end) of the tree before bringing tree indoors.
5. Inside your home, tree will absorb nearly a gallon of water the first 24 hours. Thereafter, every 3-4 days, check and add water to the tree stand reservoir.
6.Keep cut trees (and all greenery) away from fireplaces and other heat sources.

Old-Fashioned Snake Plants

Posted by Hugh on November 29th, 2016

Snake Plant (Sansevieria)

Snake plants in shady garden setting

Snake plant (Sansevieria spp.), aka Mother-In-Law’s Tongue, is an easy to grow succulent. It is one of the hardest house plants to kill, grows in almost any room of your home, and demands little attention except an occasional watering.

Its leathery sword-shape leaves are usually marked in gray green marbling. Some varieties may be edged in yellow or white. Plant varieties run from 6 inches to 4 feet in height and most are rosette form.

Snake plants tolerate low light, but grow better in bright light. They are not bothered when kept in a dark closet for 2-3 months. It grows well at room temperatures between 55 to 85 °F. Temperatures under 55 °F will mar some of the leaves. Rooms with low humidity don’t seem to bother plants. Misting foliage is unnecessary.

Water pots every 7 – 10 days thoroughly, allowing soil (potting media) to dry in between waterings. If leaves start to droop or the plant base begins to rot, you’re probably watering too much. If leaves appear wrinkled, you’re not watering enough. During the autumn and winter, reduce watering frequency to 2-3 times monthly. Prevent water from collecting in the tubular center of the plant.

Snake plants thrive outdoors in a shaded garden under a large shade tree in bright light. Add to containers with shade annuals and perennials. Plants grow vigorously and foliage coloration is more intense. Direct sun will burn the leaves of most varieties of Sansevierias.

Feed plants using a water soluble fertilizer such as Miracle-Gro® or Schultz® House Plant products. Use one-half the recommended package dose.

Repot snake plants every 12-18 months. If available, use a potting mix labeled for cacti and succulents, typically a blend of peat, bark, and coarse sand (or perlite).

White or cream colored lily-like flowers are highly fragrant and last 3-4 weeks. Flowers are attached to a long sturdy stalk and may be 3 feet high. What triggers flowering is unknown as it is a rare occurrence.

Poisonous!! Prevent pets and children from ingesting the foliage.

Christmas Vs Thanksgiving Cacti

Posted by Hugh on November 26th, 2016

Schlumbergera trucatum

2 year old plant from rooted cutting

Christmas cactus (Schlumbergera bridgesii) or Thanksgiving cacti (Schlumbergera truncata) are called holiday cacti. They are actually succulents and not true cacti. Both originate from tropical regions and make dependable, long-lived house plants.

Christmas cactus are frequently mislabeled as such and are really Thanksgiving cactus. Christmas cacti have flattened leaves with rounded leaf edges compared to Thanksgiving cactus that has pointed teeth.

Holiday cacti are short day plants. They bloom when night hours are 14 hours or longer and daylight hours are 8-10 hours long over 6 consecutive weeks. Bright outdoor lights or room lights may sometimes disrupt the dark period enough that they will not initiate floral buds. In such cases, plants may need to be covered (blackened) or moved into a closet each night.

An alternative method to induce flowering is to expose plants to cool 50-55°F temps. In warm areas in the Southern U.S. and other parts of the world, flowers may not form if night temperatures remain above 68°F regardless of daylength.

Holiday cacti should be repotted annually, preferably in February or March. Water only when potting soil feels dry or once weekly. Mist plants if the room humidity is low. Some flower buds may drop prematurely if room humidity is low or plant is open to cold air drafts. Ideal room temps are 70°F or higher daytime and 55 – 65°F at night. After threat of spring frost has ended, move holiday cacti outdoors into a partly shaded area. Continue to water and feed plants through the summer months.

Mix water soluble fertilizer products such as Miracle-Gro™, Hyponex™, or Espoma™ at one-half the package rate. Withhold winter feeding of plants until most flowers have dropped or restart in late February.

Mealy bugs and soft shell scales are potential problem pests. Overwatering leads to stem and root rots. Plant(s) may be pruned anytime for shaping. Old plants with dead or unattractive branches may be severely cutback after repotting in the spring. Such plants quickly recover.