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

Soil pH- What’s It All About

Posted by Hugh on January 18th, 2016

Rhododendron

Azaleas at Callaway Gardens

Soil pH is an indicator of the relative abundance of hydrogen (H⁺) ions and hydroxyl (OHˉ) ions in garden soils (Table 1). These ions play a very important part of soil fertility and a plant’s ability to absorb nutrients from the soil. The pH scale runs from 1 (highest acidity) to 14 (highest alkalinity). Soil pH of 7 is neutral.

Fourteen (14) of seventeen(17) essential plant nutrients are obtained from the soil. Most nutrients that plants need are readily available when the pH of the soil solutions ranges from 6.0 to 7.5, or slightly acid to neutral. Phosphorus is a major plant element that becomes less available below pH 6.0 and above 7.0.

Plants drink (absorb) nutrients that are dissolved in the soil water. Some minerals are more soluble in the company of H⁺ ions, and other minerals are more soluble in the company of OHˉ ions. Acid soils hold more H⁺ ions, and iron, manganese and phosphorus are more soluble in these soils. Alkaline soils have more OHˉ and calcium, magnesium, potassium, and molybdenum are more soluble in these soils.

Table 1: pH range and Nutrient Availability

Acidic Soil (below 7) Neutral = 7 Alkaline Soil (above 7)

More H⁺ Distilled (Pure) Water More OHˉ

Key Nutrients Most Available below pH 6: Key Nutrients Most Available above pH 7:

Iron Calcium

Manganese Magnesium

Aluminum Potassium

Molybdenum

Most (not all) nutrient elements are available between pH 6.0 to 7.0. As soil pH changes up or down, some elements becomes more soluble and available to the plant. Extremes in soil pH range, below 4.5 or above 7.7, may contain toxic nutrient levels and injure plant roots.

Certain plants have specific nutritional needs. Acid-loving plants (in the Ericaceous family) such as rhododendrons, azaleas, and blueberries are some examples. These plants don’t “love” acidic soil, but absorb higher amounts of iron compared to other plants. Ericaceous plants can not find enough soluble iron in neutral or alkaline soils where it is scarcer. They are also very efficient in absorbing phosphorus at a lower acidic pH.

Watering Tips When Away On Vacation

Posted by Hugh on January 15th, 2016

Potted Caladium and Heucheras Need Watering

Backup Watering System

Summer annuals: Hot July – August weather may demand daily or twice-daily watering for container-grown annuals. A trustworthy neighbor may have to handle these chores.

Flowers and vegetables: When there is no rain within a week, water deeply any vegetables that are bearing fruits like tomato, peppers, and squash. Plants will keep producing far into fall if supplied adequate moisture during late-summer dry spells.

Bulbs: Caladiums, cannas, elephant ears, dahlias, and others require deep weekly watering. Lilies, gladiolas, blackberry lilies, crocosmia, pineapple lilies (Eucomis), and others do not need watering.

Lawns: Cool-season grasses such as bluegrass, perennial ryegrass, and tall and red fescues will naturally go dormant. Warm season grasses like burmuda and zoysia tough it out over dry hot spells. Leaf blades turn brown, but green back up when rainfall returns. If you routinely irrigate your lawn during the summer, cutting off water may be devastating. Keep cool season grasses mowed tall, at least 3 inches or more.

Perennials: Most established perennials and ornamental grasses commonly survive moderate dry spells. Most newly planted perennials, planted 6 weeks or more and mulched, should be okay. Water perennials and grasses deeply before leaving on your trip. Shallow rooted ground covers like ferns, astilbes, and some sedges (Carex) should be irrigated by a trustworthy neighbor.

Roses: supply one inch of water per week, either from rainfall or supplied by you. Drip irrigation or soaker hoses irrigate roses without wetting foliage which can trigger disease outbreaks.

Trees and Shrubs: Some species are more drought-tolerant than others. Deeply water newly planted additions before leaving on trip; maintain 2-3 inch mulch layer around the base of young trees and shrubs to hold over trees 2-3 weeks without natural rainfall.

Houseplants: are best left in the hands of a neighbor. Otherwise, repot plants into larger containers. Small pots require more frequent watering. For extended stays away for home, first water plants thoroughly; fill bathtub with a shallow amount of water (to increase humidity). Do not set the base of pots in water. Keep room temperatures cool and reduce direct sunlight.

Tree Diversity Important In Urban Parks And Streets

Posted by Hugh on January 12th, 2016

Blue ash (Fraxinus quadrangulata) at East TN State University Arboretum in Johnson City, TN

Young Princeton elm (Ulmus Americana)

In recent years urban tree diversity has become a buzz topic. The threat of losing entire street plantings to a deadly exotic disease or pest has to often become the reality. Nearly a century ago, urban tree-lined thoroughfares were laid bare by losses of American elms (Ulmus americana) and chestnuts (Castanea dentata) to Dutch elm and chestnut blight diseases respectively.

Thousand cankers disease (TCD) is a disease complex currently threatening millions of black walnut (Juglans nigra) trees in forests and urban areas. TCD is the result of the combined activity of a fungus and walnut twig beetle.

Asian long-horned beetle continues to kill tree populations in several Mid-Atlantic and Midwest states. It is an invasive wood-boring insect that attacks hardwood trees, including maple (Acer spp.), birch (Betula spp.), beech (Fagus spp.), poplar (Populus spp.), and elm (Ulmus spp.).

Emerald ash borer is destroying native and European ash (Fraxinus spp.) across the U.S. and around the world. Oak wilt disease is laying ruin to oaks (primarily the “black oak” species) in several states.

Norway maple has been widely used on residential streets because it is a long -lived attractive tree, and holds up to soil compaction and air pollution. Unfortunately, this non-native maple is weedy, producing abundant seeds which invade native woodlands and aggressively compete with native plants.

Tree scientists are keen about Shantung or Purpleblow maple (Acer truncatum). It has an attractive appearance, but does not propagate well (USDA hardiness zones 4 – 8). This Asian maple species grows 25 – 30 feet tall and wide, is exceptionally heat and drought tolerant, and adapts to either full sun or moderate shade. Hybrid cultivars like Norwegian Sunset® and Pacific Sunset® exhibit exceptional heat and drought tolerance, good disease and pest resistance, and boasts bright red fall leaf color.

‘Norwegian Sunset’ maple (photo from J. Frank Schmidt Nursery)

Three Easy Care Foliage Plants For Your Home

Posted by Hugh on January 9th, 2016

Dumbcane (Dieffenbachia)

Calthea for sale at a garden center

Chinese Evergreen (Aglaonema), Dumbcane (Dieffenbachia), and Calthea (Calthea spp.) are three similar looking tropical house plants (USDA hardiness zones 8 through 11). Likely, you have seen these easy to grow foliage plants inside restaurants, shopping malls, offices, and at the public library.

They grow in medium to low light areas of the home or work place where many flowering plants will not thrive. They dislike room temperatures below 55 °F and a dry atmosphere. Browning leaf edges may be a symptom that room air is too dry. Turn plants every few weeks for furnish adequate light to all sides of the plant.

Spring-summer-fall fertilizing should be every 2 weeks with a water soluble “house plant fertilizer” at one-half package directions. Winter feeding is usually unnecessary. Irrigate with room temperature non-fluoridated water to avoid burning the foliage.

Plants may be moved outdoors in summer and placed under a large shade tree to receive filtered or indirect light only.

Always water plants thoroughly and do not leave them sitting in standing water for long periods. Plants should be repotted annually, usually in early fall or in late winter. Snip off older bottom leaves that have withered and died.

Diseases rarely bother all three foliage plants. Occasional pests are aphids, mealy bugs, spider mites and scales that may curl, speckle and bronze leaves. Inspect the leaf underside for webbing and spray with insecticidal soap or neem oil. Respray every one to two weeks until pest has been managed.

Chinese evergreen (Aglaonema) has a decorative patterned foliage and available in many varieties.

Dumbcane (Dieffenbachia spp.) reach heights of 4 to 6 feet; related to Aglaonema, Spathiphyllum and Philodendron.

Calthea (Calthea spp.) available in many varieties with colorful foliage and flowers in plant family Maranthaceae.

Caution: Foliage of Chinese evergreen and dumbcane are toxic and should not be ingested. If chewed or eaten, it can cause temporary swelling of the tongue and throat, leading to a temporary loss of speech and sometimes may result in suffocation. Keep plants away from children or pets. Calthea leaves are not toxic.

Asian Pears Becoming Very Popular

Posted by Hugh on January 6th, 2016

‘Korean Giant’ Asian pear

Whether home-grown or store bought, Asian pear (Pyrus pyrifolia) fruits ripen sweet and tasty on the tree (USDA hardiness zones 4-9). There are over 100 varieties available worldwide, many with difficult to pronounce.

Investigate variety cold hardiness and winter chilling rating as some cultivars are hardier than others. Southern varieties require only 300- 600 hours of winter chilling temperatures (under 45°F) to set a crop annually. They ripen on the tree (ready to eat) compared to European pear varieties that are first harvested and ripened off the tree.

Asian pears trees bear fruits in 2-3 years compared to European pears in 4-5 years. Plant bare root trees either in late winter or in early fall. You will need to plant two or more different varieties to insure good cross pollination. Trees should be set 12-15 feet apart in a well-drained, moderately acidic soil; keep the graft union 2-4 inches above ground.

Trees should be pruned during late winter. Asian pears exhibit different growth habits than European pears. Asian pears are smaller trees (usually 8 feet to 12 feet tall). Some branches develop very narrow crotch angles, which may break under a heavy crop load.

Trees should be trained to a modified leader system. At planting, cut back the central leader to 36-42 inches above the ground to encourage lateral shoots. These shoots become the main scaffold branches. Remove any broken, low branches and root suckers at any time.

Do not fertilize newly planted trees in year one. Going forward, fertilize trees annually with granular 10-10-10 or equivalent. Keep trees mulched around the base. Loosely wrap chicken wire or mesh around trunk of newly planted fruit trees to protect the tender bark from rabbits and field mice (voles). The wire should be removed after two years.

Asian and European pears have their share of disease and pest problems. Consult fruit spray guides published by your state land grant university. Some Asian pears varieties are more disease resistant than others. Unfortunately, both Asian and European pears are susceptible to fireblight.

Depending on variety and growing region, Asian pears are ready for picking from mid-July to early-October. Fruits are thin skinned.

Fall Anemone 2016 Perennial Plant of The Year

Posted by Hugh on January 3rd, 2016

‘Honorine Jolbert’ anemone

Anemone at Biltmore Estates in Asheville, NC

Japanese anemone (Anemone x hybrida), popularly called “fall anemone”, are long-lived, fall-flowering perennials for cottage and open woodland gardens. They start to flower in late summer in many parts of the U.S. (USDA hardiness zones 4 to 7). Several colorful varieties are available. Fall anemones make great additions to cut floral arrangements.

For nearly 5 weeks, showy 2-4 inch wide flowers stand 2-4 feet tall (depending on variety), on long wiry stems above dark-green basal mounds. Anemones tend to be floppy and may need staking. Each flower is composed of 6-9 overlapping white petals with numerous yellow stamens in center. The dark green leaves are 3-lobed. This long-lived perennial spreads vigorously via creeping rhizomes and seeds.

Fall anemones prefer moderately moist soils and perform poorly on dry sites. They’re best sited in partially shade locations. Foliage tends to burn in hot, dry, sunny conditions. They fail in wet clayey soggy soils over winter. Plants may be slow to establish, but, once established, will aggressively naturalize, spreading by rhizomes to form large colonies. They can be propagate by root cuttings in winter (perhaps most effective) or by division in spring.

Fall anemones prefer partial sun to partial shade, never in full day sun or deep shade. At planting time, add lots of compost to a well-drained, mildly acidic garden soil (pH 5.5 to 7.0 range preferred). Plants are mostly deer tolerant and have few disease and insect problems. From the Greek, the word anemone means “windflower”; shelter plants from extreme winds. Anemones seed in readily (think weedy).

Special note: ‘Honorine Jobert’, an heirloom hybrid anemone popular in France since the mid-19^th century, has been designated the 2016 Perennial Plant of The Year.

Cultivars to try:

‘Honorine Jobert’ (2-3 inch single white flower)

‘Queen Charlotte’ (3 inch semi-double pink flower)

‘September Charm’ (3 inch single rose-pink flower)

‘Whirlwind’ (4 inch semi-double white flower)

Invincibelle Spirit Hydrangea Raises Money For The Cure

Posted by Hugh on December 31st, 2015

Hydrangea ‘Invincibelle Spirit’ in Conlon Garden

Since the introduction of the Invincibelle Spirit® hydrangea in 2009, sales from this special plant have raised funds for The Breast Cancer Research Foundation® (BCRF). At the end of 2015, fundraising efforts reached over $900,000 toward its million dollar goal. In addition to donating one dollar for every plant sold, it serves as the heart of hundreds of Pink Day fundraisers hosted at garden centers across the United States and Canada.

Proven Winners® ColorChoice®, the brand behind Invincibelle® Spirit hydrangea, selected The Breast Cancer Research Foundation (BCRF) because it is the highest rated breast cancer organization in the U.S. with an A+ rating from Charity Watch and 4 out of 4 stars from Charity Navigator. BCRF provides critical funding for cancer research worldwide to fuel advances in tumor biology, genetics, prevention, treatment, metastasis and survivorship.

New to the campaign in 2015 was the introduction of Invincibelle Spirit® II hydrangea. This new variety improves upon the original Invincibelle® Spirit while continuing the legacy of donating one dollar from each plant sold to BCRF. The Invincibelle Spirit hydrangeas (H. arborescens) is the result of the breeding of Dr. Tom Ranney, NCSU Ornamental Plant Breeder. This new hydrangea improves upon the original with brighter flower color, stronger stems, and superior performance in containers. Like its predecessor, Invincibelle Spirit II hydrangea is a reliable re-bloomer that will perform from Manitoba to Mobile (USDA hardiness zones 3-9).

Smooth hydrangea (Hydrangea arborescens) is a loosely branched deciduous shrub that typically grows to 3 – 6 feet tall and wide in the wild. This native shrub is easy to grow in average, moisture, well-drained soil in partial sun to shade. Invincibelle® Spirit hydrangea series is more compact at 3-4 feet in height and width. Irrigate shrubs during dry periods to keep summer foliage looking fresh. It flowers on new wood from late spring thru early summer.

Credit: data on sales of Invincibelle® Spirit hydrangeas provided by Mark Osgerby, Spring Meadow Nursery, Inc.

House Plants Purify Indoor Air

Posted by Hugh on December 30th, 2015

Snake Plants (Sanseveria)

Rubber plant (Ficus)

Yes, house plants do indeed clean, filter and purify the air of various toxins and pollutants. Back in the 1980’s the National Aeronautics and Space Administration (NASA)conducted tests to determine the best house plants that helped purify indoor air in homes and work environments.

If humans were to traveled to inhospitable planets, humans would inhabit biospheres full of plants scrub the air and supply life giving oxygen. NASA proved plants could remove volatile organic chemicals from the air, including formaldehyde, tobacco smoke, and some toxic gases. Some pollutants were shown to be dangerous to human health, including some found to be carcinogenic.

Over 50 species were identified, including some popular gift giving plants like poinsettias and kalanchoes. Below is a list of twenty (20) foliage house plants that people maintain in their home and office environments.

List of 20 House Plants

Bromeliad

Philodendron vines (Philodendron)
Pothos vines (Epipremnum)
Arrowwood vine (Syngonium podophyllum)
Weeping Fig (Ficus benjamina)
Rubber Plant (Ficus robusta)
Schefflera / Umbrella Plant (Schefflera)
Snake plant / Mother-in-Law’s Tongue (Sansevieria)
Dumb Cane (Dieffenbachia)
Corn Plants (Dracaena)
Prayer Plant (Maranta)
Thanksgiving or Christmas Cactus (Schlumbergera)
Spider Plant (Chlorophytum)
Peacock Plant (Calthea)
Chinese Evergreen (Aglaonema)
Boston Fern (Nephrolepis)
Peace Lily (Spathiphyllum)
Anthurium (Anthurium)
Bromeliad (Aechmea)
Moth Orchid (Phalaenopsis)
Norfolk Island Pine (Araucaria)

Arrowhead Vine- Easy Care House Plant

Posted by Hugh on December 27th, 2015

Arrowwood (Nephthytis) Vine

Arrowwood vine in Biltmore Conservatory, Asheville, NC

Arrowhead vine (Syngonium podophyllum), often called nephthytis, is a easy to grow trailing or vertical climbing house plant. It is indigenous to the Central and South America tropics and is botanically related to philodendron. Its 5-7 inch long leaves are arrowhead shape, with a dull pointed tip (apex) and two basal lobes. Foliage of modern day varieties come in more color choices, including silvery white, cream, and pale pink variegation. Plants grow more compact and foliage is disease resistant.

Arrowhead tolerates low winter light inside the home. Grow in a east facing window with room temperatures between 60-75°F and with moderate room humidity. Plant in a potting media having good drainage and keep media moist. Water less frequently in winter and periodically mist the foliage. Every 1-2 years, repot in early spring so plant never becomes root-bound.

If moved outdoors over the summer, keep arrowhead vine under heavy tree shade and adequately watered. In early fall move all tropical plants indoors before night temperatures fall below 40°F. From spring through fall, feed plant(s) every 2 weeks with a balanced house plant fertilizer such as Peters®, Daniels®, or Miracle-Gro® diluted by half the recommended package rate; do not fertilize over the winter months.

Arrowheads are constantly growing new leaves and shedding older ones. Prune out old straggly shoots and dying foliage at any time. At start of summer, cut older vine(s) back at least by two-thirds to refreshen their appearance. Use prunings to start new plants. To propagate, take a terminal stem tip cutting or stem segment containing a healthy node, leaf and petiole.

Newly purchased plants start out trailing. Within 6-12 months some developing stems turn upright and are easily trained as a climbing vine to a pole fashioned from osmunda fiber.

Caution: Sap of this plant may be toxic to pets and cause skin irritation. Wear protective gloves when working with arrowhead vine.

Care of Holiday Cactus

Posted by Hugh on December 25th, 2015

Thanksgiving cactus

Thanksgiving cactus for sale

Thanksgiving cactus (Schlumbergera truncata) and Christmas cactus (S. bridgesii) are popular fall- and winter-flowering houseplants. Flower colors (by variety) include red, purple, lavender, cream, and white.

Holiday cacti thrive in hanging baskets. The scalped stems and foliage start out growing vertically and weeks later begin to spill over the edge of the pot. Plants flourish for many years if these simple care tips are followed.

Fall-Winter Care In Your Home: Place in bright light in an east or south facing window for maximum flower numbers. Avoid cold, drafty areas close to window or near a dry heat source. Increase room humidity by sitting the pot on a tray of moist gravel, but do not allow bottom of container to stand in water.

After bloom finishes, prune back stems to develop a bushier plant. Feed monthly with a water soluble fertilizer such as Miracle-Gro™, Peters™, Nature’s Source™, or Schultz™ at one-half package directions.

Spring-Summer Outdoors: Move plant outside once night temperatures remain above 45°F. Avoid placing cactus in direct sunlight. Over the first 1-2 weeks, acclimate the plant to outdoor temperature, light, and wind. If leaf edges start to redden, move plant to a shadier spot. Increase frequency of watering, particularly when rainfall is lacking.

Feed holiday cactus every 2-3 weeks with a water soluble fertilizer at full label rates. This is during the periods of active spring/summer growth and full bloom indoors.

To Initiate Holiday Blooms: In early to mid-October, place cactus in the dark for 12 hours daily, such as in a closet from 8 p.m. to 8 a.m. over 6 to 8 consecutive weeks. An alternative method is to chill the plant in temperatures between 50 – 55°F at night. This may be done outdoors, weather permitting. Don’t subject plant to temperatures below 40°F.

Holiday cacti are not desert cacti, but true epiphytic succulents that live in the shade of Brazilian tropical rain forests. They have high water and humidity needs. Drought is taboo to these plants; drought symptoms include shriveled scalped leaves and blooms and buds drop off. Plants need to be watered regularly, at least weekly. Plant(s) should be repotted annually, usually in March, into a larger pot containing a well-drained potting media, preferably one designated for succulents. After potting, prune the plant back by at least one-half and encourage good branch symmetry around pot.