By LSU AgCenter Horticulturists Dan Gill, Allen Owings and John Young
One of the most widely planted landscape shrubs in Louisiana is the gardenia. Several different varieties work well.
Dwarf gardenias, however, are more prone to problems that regularly occur. A planting may do very well the first year with no plants being lost, or the opposite might happen – the planting may do poorly with all plants being lost.
Sometimes a few plants in a grouping die each year; thus, after two to four years, no living plants remain. Here are a few points to consider improving gardenia landscape performance.
– Soil pH. The recommended pH for dwarf gardenias is 5.0-5.5. Adverse nutrient availability and root growth problems occur when soil pH climbs above 6.0 and become a major problem at soil pH above 6.5
– Soil drainage. Improvement of internal drainage and construction of raised beds are usually necessary when planting dwarf gardenias in Louisiana. Root rots will occur if irrigation is not properly managed and/or adequate bed preparation/soil drainage is not provided.
– Planting depth. Monitor planting depth and be careful about piling mulch around the base of the stems (this simulates planting too deep). The root ball should be a little higher than the soil line when planted in the ground. Allow for soil settling.
– Irrigation management. A slightly stressed dwarf gardenia will decline rapidly when over-watered.
– Irrigation monitoring. Watering once a week should be sufficient. Make sure distribution of irrigation is uniform. Water quality can also play a role in performance of dwarf gardenias in a landscape or wholesale nursery production operation.
– Nitrogen and iron requirement. Dwarf gardenias need a moderate amount of nitrogen fertilizer but also are harmed when nitrogen is applied excessively. Apply a recommended slow-release fertilizer shortly after spring bloom. This should handle nitrogen needs for that growing season. Dwarf gardenias are also frequently fertilized with foliar or soil applications of iron, such as Ironite. This basically offsets a slightly higher-than-recommended pH that inhibits iron uptake from the soil.
Come to LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is located near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge across the street from the LSU baseball stadium. Go online to Louisiana Yards and Neighborhoods for additional information.
Editor: Mark Claesgens
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