Garden Talk

with Rebecca Jordi


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Q: You added a swamp dogwood to your demonstration garden this year. I have never heard of this tree. Please give me more information.

Swamp Dogwood

Swamp Dogwood

A:  Swamp dogwood, Cornus foemina is found frequently throughout Florida’s wet hammocks, along the edges of swamps and floodplain forests. It grows to 15 feet high, with stiff, upright branches, reddish-purplish stems; dark green leaves which are 1 to 4 inches long.  The creamy white flowers bloom in a cluster measuring up to 3 inches across.  The fruit turn blue once they mature in the fall. Typical of most dogwood plants, this shrub is deciduous and drops its leaves in the fall.  It should be planted in partially shady sites in well-drained, moist areas but not in continually wet soil.  It prefers slightly acidic soil.


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Q: Can we grow olives here ?

Olive Fruit

Olive Fruit

A:  It appears we can.  We have two olive tree/shrubs planted in the Fruit Demonstration garden and this year we have a few olives on one of the trees. The fruit turns green in the summer and should ripen and turn black in the fall.  The olive originated in the eastern Mediterranean area, and has been cultivated by man since ancient times. Trees are extremely long-lived, up to 1,000 years, and are tolerant of drought, salt and almost total neglect.  Olive trees have been reliable producers of food and oil for thousands of years. Earliest references of olive oil use and international trade date to 2000-3000 BC. The olive was spread throughout Mediterranean Europe and North Africa very early, due to its ease of vegetative propagation and cultivation in dry climates. The Romans built on earlier work on olive culture by Greeks, Arabs, and Egyptians, and refined olive oil extraction and improved cultivars used for oil.  Today, the industry remains largely confined to Mediterranean countries of Europe, the Middle East, and North Africa, where it began thousands of years ago. The California industry began in the late 1800s as settlers planted orchards from cuttings taken from the original trees planted at Spanish missions. By 1900, there were about ½ million trees being grown in California, largely for olive oil production, but shortly thereafter, pickling and canning procedures were developed for producing black olives, the primary olive product from California today.  The trees appear to have no insect or disease issues.  Olive might be a good choice to consider as a hedge as long as we consider keeping it at a 6-10 foot height.   Check out our website for more complete information on our olive tree: http://nassau.ifas.ufl.edu/horticulture/fruit/olive.html


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Q: What can you tell me about the herb marjoram?

Sweet Marjoram

Sweet Marjoram

A:  There are three kinds of marjoram commonly used as herbs: sweet marjoram (Origanum marjorana), pot marjoram (O. onites), and wild marjoram (O. vulgare) (see Oregano). Sweet and pot marjoram are the ones usually grown in herb gardens. The perennial plants are very similar, except sweet marjoram tends to grow upright while pot marjoram runs along the ground. Marjoram is similar to oregano, but it has a finer texture. This tender perennial has a dense, shallow root system and is grown as an annual. Marjoram attracts bees and flowers late spring to summer.  When planting pot marjoram, space the plants about 12 inches apart in the row, and sweet marjoram should be placed every 6 inches. Plants can be started early in the spring from seeds, cuttings, or clump divisions. The leaves are used fresh or dried; they are similar to oregano but more delicate. Marjoram is sufficiently attractive to make an excellent border planting for a flower garden. Aromatic qualities led to its historical use as a strewing herb which means it was spread across floors of homes and buildings. Marjoram has mild antiseptic properties and is often added to herb bath mixtures. The leaves and flowers are used fresh or dried in cooking many foods, including beef, veal, lamb, poultry, fish, green vegetables, carrots, cauliflower, eggs, mushrooms, and tomatoes. Marjoram can be used to flavor stews, marinades, dressing, vinegars, butter, and oils. The plant can be grown in containers in cold hardiness zones 9-10, in full sun and well drained, slightly acidic soil. Dried marjoram can be added to herb wreaths, especially culinary wreaths. It is said to have some medicinal qualities. In ancient Egypt, marjoram was used in healing, disinfecting, and preserving. Aphrodite, the goddess of love, was said to treasure this herb. The Greeks called this plant “joy of the mountain” and used it to make wreaths and garlands for weddings and funerals. For more complete information about growing herbs in Florida, read the University of Florida publication:  https://edis.ifas.ufl.edu/pdffiles/VH/VH02000.pdf


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Q: I just moved here and there is a cluster of large bamboo plants in my yard. Can you identify them for me?

Giant Reed

Giant Reed

A:  I am glad you brought me a photo of this plant.  The grasses and grass-like plants are very difficult to identify but this one is fairly easy since you showed me a seed head and it was about 12 feet tall.  I believe is it Giant reed, Arundo donax, which is a very large plant often found growing as a dense stand in water, topped by very large, feathery, plume-like inflorescences or seed heads. Giant reed is a source of reeds for musical instruments and industrial cellulose.  Giant reed is a non-native large grass and is classified as a noxious weed in 46 states, according to the USDA. The rhizomes are hard and thick; the stems are cane-like, tall, erect or leaning reaching heights up to 20 ft. tall. The cane-like stems are what made you think it was bamboo. Controlling this plant is going to be difficult because of the rhizomes.  Applying a concentration of glyphosate (Round-up) on cut stems will be necessary to control it. It will most likely take more than one application to work.  Removing the seed heads will also be beneficial.  When removing the seed heads, be sure to bag them immediately and throw them away. 


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Q: Please identify this palm for me.

Australian Fern

Australian Fern

A:   Thank you so much for sending me a photo, which helped me narrow the field.  I believe your palm is actually an Australian fern tree, Sphaeropteris cooperi. It was introduced to the United States from Australia. The Australian tree fern is a tropical, single-trunked, giant fern. It has long, bi-pinnately compound, lacy leaves with a fine texture. The 1 to 1.5 foot long leaves form a handsome canopy and impart a tropical effect. The fern produces one trunk with a woolly appearance, and the trunk may grow to a diameter of 1 foot. This plant reproduces by spores found on the undersides of mature leaves – typical of many ferns. These spores cause problems for Hawaii’s native flora as it reproduces quickly and overtakes the native plants.  The fern tree, also called Coopers Cyathea, is considered invasive in Hawaii. It grows in cold hardiness zones 10a – 11, which is South Florida for us.  This means the tree fern really should be located in a patio or screened area here in Northeast Florida.  Consider keeping it protected if we get temperatures below freezing.  It grows at a slow rate and reaches heights upward to 18 feet with a potential 15 foot spread.  Australian fern tree prefers shady sites and will show browning on the fronds if it receives direct sunlight, especially intense afternoon sun.  It prefers sandy, moist, well-drained soils.  This plant is not salt tolerant, therefore it should not be planted along the coastline.  For more complete information please look over the University of Florida publication:  http://edis.ifas.ufl.edu/fp557


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Q: What kind of vegetables can I grow in August?

Celebrity Tomato

Celebrity Tomato

A:  There are plenty of vegetables. Consider beans (lima, pole, bush), broccoli, cauliflower, sweet corn, cucumbers, onions, Southern peas, peppers, summer or winter squash, tomatoes, turnips or watermelon. I think with that long list, you could find something you would like to plant. Let’s look at specific examples of cultivars to select such as tomatoes:
Large Fruit: Celebrity, Heat Wave II, Better Boy, Beefmaster, BHN444-Southern Star*, Amelia*, BHN 640*
Small Fruit: Sweet 100, Juliet, Red Grape, Sun Gold, Sugar Snack, Sweet Baby Girl
Heirloom: Green Zebra, Cherokee Purple, Eva Purple Ball, Brandywine, Mortgage Lifter, Delicious
*Resistant to TSWV (Tomato Spotted Wilt Virus)
For more complete information, specifically the best cultivars for our area; look over the publication from the University of Florida:  http://edis.ifas.ufl.edu/vh021