LSU AgCenter Ornamental Horticulture E-News & Trial Garden Notes Early and Mid May 2016

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1 LSU AgCenter Ornamental Horticulture E-News & Trial Garden Notes Early and Mid May 2016 Nursery, Landscape & Garden Center Updates Compiled by Allen Owings, Professor (Horticulture), Hammond Research Station, LSU AgCenter Edited by Rick Bogren, Professor (Communications), LSU AgCenter Phone ; Headline News and Other News Notes of Interest SunPatiens May 5 Mid South Green Industry Conference 2016

2 LFVGA Spring Meeting and Olive/Fig Field Day May 19

3 LSU AgCenter Control Information for Chamberbitter/Phyllanthus (from Ron Strahan and Dan Gill) Landscape Beds: This summer annual weed can be controlled in beds by hand weeding the bed or using a nonselective herbicide. Hand weeding works well because there are no below ground bulbs or rhizomes to resprout. Where you can apply an herbicide just to the foliage of the chamberbitters without getting it on the nearby desirable plants, you can use glyphosate (Eraser, Killzall, Roundup, Grass and Weed Killer). Use a shield when spraying or cover nearby ornamentals with plastic sheeting or bags to prevent the spray from getting on them. If the herbicide gets on the foliage of desirable ornamentals, it will damage or kill them. Once the weeds have been cleaned out of a bed by hand weeding or glyphosate, thoroughly mulch it with 2 inches of mulch to minimize new weeds showing up. The mulch will suppress the germination of the chamberbitter seeds in the soil. The thickness of the much is important for effective control. Chamberbitter does not respond well to some preemergence herbicides, but isoxaben is recommended in some publications. After hand weeding or killing with glyphosate, apply a product containing isoxaben (such as Green Light Portrait Broadleaf Weed Preventer) following label directions. But 2 inches of mulch will also do a good job suppressing weed seeds. In Lawns/Turf: If you have St. Augustine, centipede or zoysia, spot treat with atrazine during the summer. It is too hot to apply over the entire lawn, but you can spray spots or patches of the chamberbitter weeds where they occur. Make two applications following label directions. Atrazine also serves as a preemergence herbicide, so the areas where you have treated twice should not see much regrowth. (Do not use atrazine in beds.) For best control, spray the lawn with atrazine in early to mid-may before it gets so hot. Then, spot treat during the summer if needed. Isoxaben (see above) could be applied to the lawn in early summer as a preemergence herbicide to prevent seeds of this weed from sprouting and growing. Also, mow your lawn at the highest recommended height to make it more competitive St. Augustine at 3 inches, centipede and zoysia at 2 inches. A bad chamberbitter infestation in a lawn may indicate a lawn that is in poor vigor. Chamberbitters have a harder time establishing in a thick, healthy, vigorous lawn. Make sure you provide your lawn with proper care (mowing, watering, fertilizing, sun) to minimize chamberbitter problems.

4 Success with Oakleaf Hydrangeas (from Allen Owings) May is when hydrangeas in Louisiana landscapes began bursting into flower. Hydrangeas are part of our Southern landscape heritage. Garden hydrangeas, with their pink or blue flowers, have been around the southeastern United States for 250 years since their introduction from Japan. We do, though, have other species of hydrangeas that are native and could be an alternative landscape selection. Oakleaf hydrangea, scientifically called Hydrangea quercifolia, is indigenous to the southeastern United States. It grows in nature in mixed hardwood forests, along streams and on forested hillsides. Plants are usually found on calcareous soils. Oakleaf hydrangea is an understory shrub and grows, adapts well in shade provided by oaks, hickories, magnolias, and American beech. This shrub grows to 6 to 10 feet tall and has deeply lobed, oak-like, 8-inch leaves, which turn reddish bronze in fall. The whiteflowered panicles start opening in late April through early May in Louisiana and gradually turn pinkish as they age. Notice the sun and shade situations where you might consider planting. Oakleaf hydrangea can colonize an area, spreading by stolons. Hydrangeas prefer to grow in well-drained soils containing plenty of organic matter. Most species prefer warm, morning sun and cooler, afternoon shade. Avoid deep shade. Flower production is better with about five hours of direct sunlight in the morning. Oakleaf hydrangea is especially sensitive to saturated soils. Root rot of hydrangeas is a common problem in Louisiana. This is due to poorly drained soils and is common after significant rain events. Even large, established plants may die in this situation. There are several recommended oakleaf hydrangea varieties to plant. Consider Alice, Snowflake and Ellen Huff. Alice produces creamy white, 10- to 14-inch inflorescences. It tolerates more sun, and foliage turns burgundy-red in fall. This selection is from the University of Georgia. Snowflake is special due to its double sepals that make blooms appear to be double. The florets continue to open throughout summer, giving 'Snowflake' a longer bloom time than any of the single-sepal varieties. Plants can grow to be 8-10 feet tall.

5 Ellen Huff is a strong grower from the Gulf Coast area. It is a variety that needs more use and availability. This variety has good heat tolerance. Plants reach 6-8 feet tall. The USDA has some new varieties of oakleaf hydrangea Queen of Hearts, Munchkin and Ruby Slippers. These have been performing well in the landscape of the Piney Woods Garden at the LSU AgCenter research station in Hammond. Some garden centers sell unnamed oakleaf hydrangea seedlings. When they are available, consider obtaining those from more Southern plantings in order to achieve the best success in Louisiana. Oakleaf hydrangea success includes a well-rooted plant, a morning sun/afternoon shade planting location, well-drained soil with a ph of , and consideration for planting in the fall. Remember that every landscape in Louisiana may not have an ideal location for this great native. Following these guidelines, though, will aid in success. Grandstand Salvia from Green Fuse Botanicals Grandstand is one of the new vegetatively prorogated annual salvias. From Green Fuse Botanicals, the series is currently being trialed at the LSU AgCenter Hammond Research Station. Grandstand is ideally suited for 8-inch and larger containers. Grandstands are a true breeding breakthrough for their continuous flowering until autumn frost. Expect highly branched plants and extra-large flowers that create tremendous color in the landscape. The series introduction included Lavender, Purple and Red for the 2016 spring sales season. Green Fuse also has Blue Bicolor (pictured) and Salmon in production as a trial offering. The series seems to not have a day-length flowering response.

6 Plants with Potential for 2016 Introduced at Spring Industry Field Day (from Jason Stagg, Gina Hebert and Allen Owings) "Plants with Potential" is a new outreach program created at the Hammond Research Station last year to annually introduce and distribute unfamiliar, non-patented plants to our nursery and landscape industry. Species selected for this program have excellent landscape performance potential in the challenging Gulf South climate but are not commercially available in the trade. Nine species were introduced in 2015 and six more in plants are: 1. Copper Plant Kapioloni Bronze 2. Copper Plant Musaica 3. Begonia Barbara Rogers 4. Lantana Belle Starr Gold 5. Geranium Mary Helen 6. Pentas Nova 7. Purslane Florida Dwarf Rose 8. Salvia Silke s Dream 9. Turnera Trailing Yellow 2016 plants (continuing numbering system) are: 10. Aerva sanguinolenta Amaranthaceae (Red Velvet Plant) Unusual tropical foliage plant ideal for bed edgings and mixed containers. Aromatic, richly-colored burgundy leaves. Produces small Alternanthera-like flowers during short day seasons. Grows 18 inches x 14 inches. Plant in full to partial sun. Easily propagated by cuttings. Can be perennial in warmer areas of Zone 9. The LSU AgCenter provided this plant to the LSHR for its 2016 plant release. 11. Cestrum x Orange Peel Solanaceae (Orange Peel Cestrum, Orange Peel Jessamine) This is one of the best cestrums at the Hammond Research Station. A hybrid of Cestrum diurnum x Cestrum nocturnum, this large tropical shrub will take the heat and can quickly grow to 4-8 feet x 3-5 feet, making it an ideal background planting. Dark green, deer-resistant narrow leaves provide good contrast for the numerous golden yellow/light orange tubular blooms. Plant in full sun with good drainage. Excellent hummingbird and butterfly attractant. Fragrance is released at night, but does NOT smell like oranges! Blooms May-June until first frost. Propagated by cuttings. Wholesale availability from Southwest Perennials in Dallas, Texas. Can be a deciduous shrub in warmer parts of Zones 8 and 9, but may die back to the roots during cold winters of Zone 8. Needs good winter soil drainage. 12. Glandularia canadensis Carlos Verbenaceae (Carlos Verbena, Carlos Smith Verbena) Unique bi-color blooming verbena named after the late LSU AgCenter Avoyelles Parish agent/horticulturist Carlos Smith, who collected it from his great aunt s home site near Monroe, Louisiana. Possibly dates to the 1890s. Striking white to lavender flower clusters adorn silver-green foliage. Individual flowers can express both colors. Early season bloomer that slows during the summer heat. Cut back clump in late summer for blooms to reappear in fall. Prefers drier soils, so good drainage is important. Excellent in hanging baskets and containers. Attracts butterflies. Grows 9-10 inches x inches. Propagates easily from cuttings. Typically evergreen in Zones 8 and 9.

7 13. Glandularia canadensis Snow Flurry Verbenaceae (Snow Flurry verbena, possibly Colonial White verbena) If you only have room for one verbena other than Homestead Purple, this is it! The Hammond Research Station received its original plants from Billy Welsh at the Ira Nelson Horticulture Center in Lafayette, Louisiana. Pure white flower clusters bloom profusely on lush, dark green foliage. Vigorous grower is more upright than most verbenas. Fewer disease or pest issues. Will bloom all year long, but spring and fall flushes are the most spectacular. Flowering slows during the heat of summer. Should be considered for fall-planted winter color as a companion to violas and snapdragons. Grows 8-12 inches x inches. Plant in full sun with good drainage. Beautiful in containers and hanging baskets. Propagates easily from cuttings. Butterfly attractant. Retail availability from Plant Delights Nursery in Raleigh, North Carolina. Evergreen in Zones 8 and Iresine herbstii Amaranthaceae (Red Iresine, Bloodleaf Plant, Chicken Gizzard Plant, Beefsteak Plant) Striking, colorful, lush tropical foliage plant has burgundy or red leaves with magenta veining. Can be used as an annual similar to coleus. Grow in full sun or part shade. Average size is 1-2 feet x 1-2 feet. Water regularly. Occasionally found at retail garden centers. Very easy to propagate from cuttings. May be cold hardy in Zone Pentas lanceolata Pink Remembrance Rubiaceae (Pink Remembrance Pentas) This old variety is very similar to Nova but has a softer, light pink bloom that looks great planted with Nova. Plants at the Hammond Research Station are hardy but not quite as vigorous as Nova. Grows to 3 feet x 2 feet in full sun. Large clusters of 3-4- inche, light pink, star-shaped flowers appear atop dark green leaves from late spring through fall. Excellent butterfly and pollinator attractant. Not known to be available commercially but has been established for years at the New Orleans City Park Botanical Garden. Propagated by cuttings, but less success than Nova. Perennial in warmer areas of Zone 9. LSU AgCenter Plant Diagnostic Clinic