EDITOR’S NOTE: A University of Florida faculty member and Nassau County Extension Horticultural Agent, Rebecca Jordi addresses some of the questions she receives about landscaping and gardening in northeast Florida, in GARDEN TALK. The Extension also offers helpful clinics throughout the year, providing assistance to local gardeners on Amelia Island and in the surrounding areas of Nassau County, Florida.
Growing Gardenias in Northeast Florida
GARDEN TALK _________________
QUESTION: My gardenia is showing yellowing leaves. My neighbor told me to add iron sulfate. Will it help? TO
JORDI: Adding iron sulfate to the soil around the root area of the gardenia may help if the problem is a deficiency in iron. Yellow leaves may be the result of low nitrogen levels or high pH soil among other things. If the pH of the soil is too high then even the presence of enough iron will not solve the problem completely.
You might consider working materials into the soil such as peat moss or coffee grinds which will lower the soil pH on a temporary basis. Consider using pine products for mulch as they also help lower the soil pH. The “sulfate” part of iron sulfate can also temporarily lower soil pH so the plant is able to absorb the nutrients it needs.
It is best to use an acid loving fertilizer on plants such as azaleas, camellias, gardenias and holly as it should contain the element sulfur. Recognize the sulfur? Yes, you are correct; this also lowers the pH slightly on a temporary basis.
Did you also notice I have stated several times the pH is lowered on a “temporary basis”? Lowering pH or trying to make it more acid is difficult and can usually be done only for a short span of time. The natural tendency of alkaline soil is to stay alkaline. Any Extension office will be glad to run a soil test for you to determine the soil pH. Please call the Nassau County, Florida office at 904-548-1116 or 904-879-1019 to determine the best time to drop off your soil specimen. This test is free of charge but please limit the number of samples you bring in to no more than two or three. Take your soil samples where roots would be growing rather than just skimming the top of the soil.
The gardenia photo (above) is from Clemson University. For more complete information regarding soil pH, check out the University of Florida publication titled “Soil pH and the Home Landscape or Garden”: http://edis.ifas.ufl.edu/ss480
For additional information on growing gardenias in Florida look at the following publication: http://edis.ifas.ufl.edu/pdffiles/MG/MG33600.pdf
QUESTION: My Queen palm appears to be dead. Will it come back? GP
Freeze Damage on Queen Palm, Northeast Florida
JORDI: The short answer is you will have to wait until later in the spring by determining if any fronds come out green. The long answer is regarding which palms really can tolerate our colder winter weather. I know you are thinking you moved here because the average temperature is well above freezing, which is true, but nothing about this and the previous winter falls into the “average” category.
Queen palms, Syagrus romanzoffiana, have feathery fronds and tall slender trunks which reach heights of up to 50 feet. The cold hardiness zone for this palm is 9B – 11 (remember we are in cold hardiness zone 8B-9A which is just above the Queen palm’s preferred area). This explains why so many of these palms have suffered over the last two years.
CHOOSE A COLD-HARDY PALM FOR NORTHEAST FLORIDA
It would be better to choose a cold hardy palm such as Pindo, Cabbage, Chinese Fan or Indian Date. Refrain from planting the Pygmy Date Palm, Phoenix roebelenii, as it is also a south Florida palm in the 10-11 cold hardiness zones. (The photos here were taken by me last year after the freezing temperatures occurred and the Queen and Pygmy palms did not recover. )
We have several cold hardy palms in the UF/IFAS Nassau County demonstration garden, which we will be refurbishing later this spring and summer if we receive the grants we wrote this winter. Remember to use palm fertilizer on your palms spring, summer and fall. For more complete information check out the publications from the University of Florida on the Queen palm: http://hort.ufl.edu/trees/SYAROMA.pdf and the Pygmy Date palm: http://hort.ufl.edu/trees/PHOROEA.pdf
QUESTION: What is wrong with my sago palm? The newer fronds are brown and twisted. EB
Frizzle Top on Sago Palm, Northeast Florida
JORDI: Your sago palm appears to have a nutrient deficiency called frizzle top. The photo I took shows several seasons of fronds which have experienced this nutrient problem.
The sago is lacking manganese (Mn), which can be found at your local garden center in the form of manganese sulfate. Do not confuse manganese sulfate with magnesium sulfate which is the ingredient found in Epsom salts. You will need to be sure to add manganese sulfate to your normal palm fertilizer if it does not already contain manganese. The fertilizer should be spread totally under the canopy of the fronds. Add a small amount of water to be sure the fertilizer reaches the root area.
Adding Mn now will not change the look of the current fronds. However, do not be tempted to remove all the ugly fronds, especially if they still have any green color. The green color tells you the fronds are still providing food to the palm and removing them will stress the palm even more. Regarding removal of palm fronds, it is best to keep all fronds on all palms until they are totally brown.
Rebecca Jordi
Rebecca L. Jordi
University of Florida/IFAS
Nassau County Extension
Environmental Horticulture Agent III
543350 U. S. Highway #1
Callahan, FL 32011
904 548-1116 or 904 879-1019
http://nassau.ifas.ufl.edu
