Ornamental Horticulture Update

Sweetbay Magnolia

Dec 19

Written by:
Monday, December 19, 2011

Ornamental Plant of the Week
December 26, 2011

Sweetbay Magnolia

from Allen Owings

(Note: Sweetbay Magnolia will be a Louisiana Super Plant for fall 2012!)

Sweetbay magnolias are native to a large portion of the eastern and southeastern United States. They are very common in the coastal regions of Louisiana, Mississippi and Alabama and are found in association with swamp red maple (Acer) and titi (Cyrilla). These magnolias perform well under a wide range of soil and planting conditions – their native habitat is swamp, bog, pond or sandy stream areas, but they grow best in fertile, moist, well-drained, silty loam soil. A slightly acid soil is preferred.

An upright, columnar type growth habit having a single truck is what you will see with most sweetbay magnolias planted in a commercial landscape setting. But you will see sweetbay magnolias with multi-trunked, shrubby growth forms also. In their native habitat, plant size and growth habit are highly variable. Pruning at a young age can be used to direct shoot growth to the desired form.

Mature trees will average about 30 feet tall with a spread of 20 feet, but larger sizes are common. Most of the time, these trees have a tendency to be semi-evergreen. The further south they are planted, the more likely it is for foliage retention to extend into winter. Some improved selections of sweetbay magnolia are close to being evergreen. A nice feature of the sweetbay magnolia is the silvery gray color on the underside of foliage. Flowers are creamy white and about 2-3 inches in diameter. Flowers are present in April and May and have a lemony fragrance. Fruit is your typical magnolia cone that is yellow-green. It splits open in late summer through fall to reveal red seeds.

Sweetbay magnolias are being produced more now in wholesale nurseries. Landscapers are using the tree in commercial plantings. Trees are good for wildlife habitat plantings. In the home landscape, they make a great small-to-medium-size tree for a woodland edge situation. They work well as individual specimen trees or in a clustered group of 3-5 trees. Try to select trees for grouped plantings that have similar habits.

FURTHER ARTICLES

A Final Review of People’s Choice Winners for 2011
Amaryllis Information
Sustainable Landscape News Articles

A Final Review of People’s Choice Winners for 2011
from Allen Owings

The LSU AgCenter’s Hammond Research Station evaluates ornamental plant performance in the landscape and hosts many events for home gardeners, Master Gardeners, and nursery and landscape professionals throughout the year. Being at year’s end, here’s a report of the plants that were People’s Choice winners this past year.

Over 130 nursery and landscape professionals attending the landscape horticulture field day at the LSU AgCenter’s Hammond Research Station on October 18 were provided an opportunity to vote for their two “favorite” plants in the sun garden plant trial evaluation area at the station. Plants in the sun garden are annual bedding plants for sun, herbaceous perennials, roses and companion woody ornamental shrubs and small trees.

Gold Winners, receiving the most votes by attendees, were Carefree Celebration rose and pink muhly grass. The Silver Winner was the new Sombraro Salsa Red echinacea (purple coneflower). Bronze Winners were Double Scoop Bubble Gum echinacea, Mesa Bright Bicolor gaillardia (an All-America Selection winner), Henry Duelberg salvia and Belinda’s Dream rose (a fall 2011 Louisiana Super Plant).

Others plants receiving a significant number of votes included Babywing Pink and Babywing White begonia, Carita Purple angelonia, dwarf tibouchina (princess flower), Bandana Lemon Zest lantana, Bandana Rose Improved lantana, Carefree Marvel rose, Black Pearl ornamental pepper, Golden Edge duranta, Henna coleus, Marginata Bronze copper plant, Dreamland Scarlet Elegance zinnia, Florida City Bonnifay coleus, and Profusion Double Fire and Profusion Orange zinnia.

320 Louisiana Master Gardeners attending an “Appreciation Day” at the LSU AgCenter’s Hammond Research Station this past spring also voted for their People’s Choice winners. We had a total of 384 votes for the spring 2011 Master Gardener People’s Choice plant awards. The medal winners received 19.5 percent of the total votes. Other plants receiving significant votes accounted for 63.3 percent of the total votes, and plants not listed received the remaining 17.2 percent of the total votes.

The Gold Winner was the cool-season Guardian Blue delphinium, with the Silver Winner Redbor kale (a fall 2011 Louisiana Super Plant) and Bronze Winner PowWow Wild Berry purple coneflower (a 2010 All-America Selections winner).

Others plants receiving significant votes were Camelot Rose foxglove (a fall 2010 Louisiana Super Plant), Blue Chip butterfly bush (buddleia), Shoal Creek vitex (a spring 2011 Louisiana Super Plant),Spreading Salmon Variegated, Compact Blush Pink and Compact Orange SunPatiens, Cassia corymbosa, Fireworks gomphrena, Curled Green and Starbor kale, Early Bird Gold black eyed Susan, Tricolor hibiscus (Hibiscus tiliaceus), Cherry Brandy hardy hibiscus, Tidal Wave Silver, Suncatcher Pink Lemonade, Tidal Wave Hot Pink and Picnic Light Pink, All the Rage Easy Elegance rose, Frostproof gardenia (a spring 2011 Louisiana Super Plant), Guardian White and Guardian Lavender delphinium, dwarf variegated tibouchina (princess flower), Sorbet Lemon Royale and Sorbet Lemon Chiffon viola , President canna, Saratoga Red and Perfume Antique Shade nicotiana (flowering tobacco), PowWow White echinacea, Wasabi coleus, Julia Child rose, and Curly Q copper plant.

Louisiana Master Gardeners attending the appreciation day also were provided a survey to indicate areas of interest in ornamental/landscape plant evaluation research. Participates were asked to vote for three plant categories from the list provided. Percentages of Louisiana Master Gardeners desiring research in the following topic areas were: Future Louisiana Super Plants – 70.2%, new herbaceous perennials – 66.0 %, new herbaceous annuals – 42.6%, new purple coneflowers – 34.1%, butterfly bush cultivars – 25.5%, Easy Elegance shrub roses – 23.4%, foliage (coleus, Joseph’s coat, copper plants) – 23.4%, Southern Living trees and shrubs – 10.6%, heirloom hybrid tea roses – 6.4%.

Interest in Louisiana Super Plants is considerable among Master Gardeners, especially what is coming in the future. In addition, it was interesting to note the desire for information on new herbaceous perennials (66 percent) – as compared with annuals (42.6 percent). There also seems to be some desire for alternative rose cultivars. It was also noted that specifically focused areas, such as butterfly bushes (Buddleia) and purple coneflowers (Echinacea), received high marks.

Home gardeners from south Louisiana attending events and garden strolls at the station this past spring also voted on their People’s Choice selections.

Their Gold Winner winner was Guardian Blue delphinium. The Silver Winners were PowWow Wild Berry Echinacea and Guardian Lavender Delphinium. Bronze Winners were Suncatcher Pink Lemonade petunia, Tidal Wave Silver petunia and Peppermint Schnapps hardy hibiscus. Other receiving consideration in the vote totals include Intensia Lavender Glow and Intensia Blueberry phlox, the Sanguna series of petunias, several colors in the Lani series verbena (primarily Bright Pink, Purple Rain Mix, Twister Pink and Lavender Star), the Sorbet series viola (primarily Blue Heaven, Yellow Delight and Black Delight), Compact Blush Pink SunPatiens, Tidal Wave Cherry and Tidal Wave Hot Pink petunia, Guardian White delphinium, Fireworks gomphrena, Camelot Rose foxglove, Starbor and Redbor kale, Saratoga Red nicotiana (flowering tobacco), New Blue Wonder Scaevola (fan flower), Blue Chip butterfly bush (Buddleia), Opelousas Red copper plant and White cat whiskers (Orthosiphon).

LSU AgCenter Plant Disease Diagnostic Clinic

Amaryllis Information
from Jeff Kuehny

Amaryllis species and hybrids (Amaryllidaceae family, genus Hippeastrum), grown from bulbs, have long been a favorite flowering plant in U.S. homes. What Americans have called an amaryllis for many years is actually a Hippeastrum. These plants are native to the tropical areas of Brazil where they are considered more of an evergreen perennial. The flowering bulbs belonging to the genus Amaryllis are native to South Africa and vary from Hippeastrum by differences in their inflorescence. These are not used commercially as Hippeastrum
.

In subtropical climates (USDA Hardiness Zones 7b through 8) Hippeastrum bulbs flower naturally during April and May. Foliage matures and slowly fades during the summer. In autumn the bulbs go dormant (whether this is true dormancy is a subject of debate) until emergence of leaves and usually two buds per bulb each spring. Dormancy can be imposed by harvesting the bulbs, shipping temperatures, storage temperatures or drought. Most of the Hippeastrum grown commercially for forcing are hybrids, but numerous species and hybrids should be reconsidered for their use as both flowering pot plants and landscape plants. Some of these bulbs have been grown in Southern landscapes for years and are often referred to as the “Lily of the South.”

Hippeastrum x johnsonii, often referred to as Saint Joseph’s lily in the South, has a bright red flower that has a thin white stripe down the center of each petal. A close relative is the Voodoo Lily (Naughty Lady) – variety names – that have a broader white stripe and recurved petals. Many of the more popular hybrids used as flowering, potted plants will also do well in the landscape. These plants require a well-drained soil and full sun for best growth. If you decide that Hippeastrum won’t work for your customers as landscape plants, then consider growing them as potted plants. Their popularity, especially as an alternative Christmas holiday pot plant, has steadily increased.

The sale of Hippeastrum bulbs for forcing occurs in late August and early September. The bulbs can be marketed as “dry bulbs” to be potted in soil or gravel by homeowners or sold in ready-to-plant kits where the bulb, pot and soil are sold in a decorative box. The plants can also be sold as a finished flowering pot plant for use in the home, office or large commercial interior display. Whether the plants are sold as flowering pot plants or as a dormant bulb to be forced, they have a high dollar value.

Hippeastrum bulbs are planted in pots in October through January for production as potted plants. There is simultaneous emergence of four leaves and a 12-inch flowering stalk. The average forcing time to market stage is three to five weeks. Sizes for bulb grades for commercial use are 20-22, 22-24, 26-28, 30-32 and 32-up centimeters in circumference. Flowering is regulated by bulb size (diameter or circumference and not by weight) with a minimum size of 20 centimeters (8 inches) in circumference.

The environments for bulb production and storage vary among growers and by the country in which they are produced. Bulbs produced in the Netherlands, Israel, South Africa and Brazil are harvested at different times of the year, resulting in storage times and temperatures that vary. These differences in harvesting have had a positive impact by providing a greater availability of bulbs at reduced prices. However, these differences have also increased the variability in growth and flowering during forcing. Because these bulbs are brought out of storage for forcing or for sale as a dormant bulb, emergence and flowering may be highly variable.

Growers should pay careful attention to where the bulbs originated and the storage conditions they were exposed to before they were delivered. If bulbs are going to be stored prior to forcing, the storage temperature should not exceed 48 degrees, and they should not be stored for more than 15 weeks. The minimum storage temperature is 41 degrees, which causes more rapid emergence and flowering. Different varieties will respond differently to storage times and temperatures.

High temperatures during forcing (77-86 degrees) hasten development and elongation of the leaves and increase growth of bulbs, but may prevent flowering. Low temperatures (54-63 degrees) cause the leaves to unfold and elongate slowly, and bulbs are slow to enlarge with little floral development. Temperatures of 63-75 degrees induce intermediate vegetative growth and bulb enlargement and optimum flower emergence. Research has found that there is no effect of day length on growth and flowering.