Ferns

Q:  Please give me some alternatives to Boston fern.

A:  We have several different ferns which behave themselves to much better than Boston fern but Royal fern, Osmunda regalisstill have similar light (shady) requirements.  Here are just a few:  Royal fern, Osmunda regalis, can be found growing in cold hardiness zones 3-10; shrives in rich, organic soils, can reach heights up to 6 feet but will generally die back in the winter.  Good news – the deer don’t seem to like it.  New growth in the spring is a pretty pale pink. Giant leather fern, Acrostichum danaeifolium, is a Florida native fern.  This can grow in cold hardiness zones 8b – 12b – definitely not a northern U.S. fern.  Individual fronds can grow up to 12 feet tall and the plant can spread to 5 feet wide. This fern prefers to grow in moist soil and is often found along fresh water swamps. To keep the plant looking its best in cultivated areas, consider removing old fronds and annual fertilization is not required. Maidenhair fern, Adiantum spp., is also a Florida native fern. Maidenhair fern has delicate fronds and is fund more often in Central and Southern Florida in cold hardiness zoned 9-11 but could be planted along the eastern coastline. This fern might be a good choice for smaller landscape areas as it grows 3 feet tall and 3 feet wide. The southern maidenhair and brittle maidenhair grow best in alkaline soils while others grow best in acid soils. With so many of our along the coast having high soil pH readings, this is a good plant to consider for shady sites. It will cascade over the side of a container in a shady garden spot. Some of the available species include: Adiantum capillusveneris, southern maidenhair, 1.5 feet tall; A. hispidulum, rosy maidenhair, one-foot-tall, young fronds rosy brown; A. pedatum, western maidenhair, 1 to 2.5 feet tall, most popular one grown; and A. peruvianum, silver dollar maidenhair, 1.5 feet or more tall, leaf segments quite large, up to 2 inches wide.  Then consider other common ferns such as holly fern, autumn fern, and staghorn fern. 

Asparagus Fern

Q:  What is the name of this fern growing it all over my neighbor’s yard.  It is very pretty and filly, but I noticed it has tiny thorns. 

A:  The plant you showed me is called Asparagus fern, Asparagus setaceus, but it is also known as Common Asparagus Fern.  There are many varieties of asparagus fern and a few, such as Asparagus aethiopicus, are classified as type I Invasive according to FLEPPC (Florida Exotic Pest Plant Council).  Common Asparagus Fern is native to the moist, forest areas of South Africa.  It prefers dappled light but can tolerate a wide range of light conditions once it is established.  Common Asparagus Fern is slightly drought tolerant but it responds well to occasional irrigation.  Its cold hardiness zone is 9-12, which means it can die back during cold winter seasons in zone 8.  It can over-grow perennials although it is not as aggressive as similar vines.  Common Asparagus Fern is not a true fern as it produces flowers and seeds rather than spores. Don’t be fooled by the soft, feathery look of the leaves as the stems have small, fine needle-like projections that prick like thorns.  These projections make it unique from other asparagus species and therefore easier to identify.

Austrailian Fern

 Q:  Please identify this palm for me. 

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

 

Autumn Fern

Q:  I have a very shaded lot and I have been adding ferns to my landscape.  I know this is a silly question, but I want to know why they call my most recent purchase - autumn fern. 

A:  No question is silly if you are curious about the answer.  Dryopteris erythrosora, Autumn Fern, is also commonly known as Japanese Shield Fern. It has a slow spreading habit and an ability to tolerate neglect which makes it an ideal candidate for use as a groundcover here in Northeast Florida.  Autumn fern is one of the few ferns to have seasonal color value; the newly forming fronds appear red to purple in color when young.  It is this combination of colors on the new growth which give it the name autumn fern. It will grow to about 18 inches tall with single plants spreading no more than 24 inches. It requires very little care, tolerates most any kind of soil but must be grown in partial shade to full shade.  For more complete information, please look at the University of Florida publication by Dr. Ed Gilman: http://edis.ifas.ufl.edu/fp189

 

Bird's Nest Fern

Q:   I am having large dead areas on the leaves of my bird’s nest fern.  What is wrong with it? 

A:  Bird's-nest fern, Asplenium nidus, is a large epiphytic fern, with erect, simple, wavy, bright green leaves which can reach lengths of 4 feet. Asplenium nidus `Crispafolium', the wavy Bird's-nest fern, is similar to Bird's-nest fern but fronds are much wavier. This plant grows best in warmer, humid climates.  It does not tolerate temperatures below 40°F.  Bird’s nest fern needs continual moist soil; it should never be allowed to go dry between watering.  The linear lines you see are spores from which new plants can be propagated.  The large dead areas are probably caused by fungal spores.  Plants often have disease issues when grown out of their preferred environment.  Bird’s nest ferns might work best in interior environments here as long as they are receiving sufficient humidity such as a bright, sunny bathroom.  In additional, this plant, when grown outside, prefers shady sites so placing it in full sun areas can cause even more stress.  If you plan to keep it, you might consider moving it to a different site, perhaps a screened pool area or under large shade trees. The plant may grow better in protected areas, away from dry cool air or full sunny spots.  In south Florida, these plants are often hung under tree limbs to give them dappled light, high humidity and temperature protection, in other words… the perfect environment.

Christmas Fern

Q   I received a plant catalog and they mentioned Christmas fern.  Can we grow it here? 

A:  According to North Carolina State University, it is in cold hardiness zone 9, so you might want to try it.  Christmas fern, Polystichum acrostichoides, gets its common name from some parts of the plant remain green throughout the year in Northern states which makes it one of the few available greenery plants for use in decorations at Christmas time. The dark, green leaves (fronds) of the fern grow from 2-3 feet long and are about four inches wide. They are tough, leathery and have a pointed tip. The fronds are attached to a relatively short stalk that is brown at its soil base and green toward its apex.  So don’t worry if you see the color differentiation – it is perfectly normal. It can grow in dense shade to partial shade, but must be kept out of the sun.  Dappled light through tree canopy would be acceptable.  Soils of moderate moisture and a more neutral pH are preferred. This pH preference is reflected in the increased densities of Christmas ferns in soils found in areas which overlie limestone bedrock, a similar situation for Northeast Florida. Christmas fern is seldom found in soils too waterlogged, so be sure you do not over-water these plants. All of my ferns are seldom watered except by rain.  Christmas ferns, like many other ornamentals, are susceptible to fern scale insects and mealy bugs which can cause extensive damage to the plants if not caught early. Food grade diatomaceous earth (not the powder used in pool filtration) will control the mealy bugs. You can also apply ultra-fine horticulture oil or insecticidal soap for the scale or mealy bugs.  Christmas fern is a much better choice of fern than the Class I invasive Boston or Sword fern.  Please, please, please, stop planting the invasive fern (Boston) in the landscape and in palms – sorry, I got on my soap box!

Ghost Fern

Q: I have a very shaded lot and I am thinking of adding more ferns to my plant beds.  What can you tell me about the Ghost fern?  It sounds so intriguing. 

A: ‘Ghost’ is a hybrid fern which was developed from a cross between Athyrium niponicum var. pictum and Athyrium filix-femina.  It gets the popular name Ghost because of the silvery color of the outer edge of the fronds.  When temperatures get warmer, the color often gets a hint of blue. The silver color on the fronds comes from its Japanese painted fern parent and the upright growth of the fronds comes from its lady fern parent. It generally grows to no more than 2 ½ feet tall with an even smaller spread. The mature size makes it a wonderful plant for small, shade gardens. It can tolerate dappled light, but direct afternoon sun here will cause brown edges and the plant will be very unattractive if it survives.  Ghost fern is less sensitive to dry soils but it should not be allowed to get too dry.  If you have a rabbit problem, this plant does not appear to be very appetizing to the furry creatures.  However, I must warn you, if rabbits or deer get hungry enough, they will eat most any plant. I have a Ghost fern in my garden now, and it survived the winter beautifully.  In some colder climates, the fern is considered deciduous, meaning it will lose its fronds but return when temperatures are warmer.  Its cold hardiness zone is 4-8. I am in cold hardiness zone 9a, so those of you on the east part of Nassau County Florida might want to add this little beauty to your landscape. Those of us on shaded lots should consider adding more ferns as they add texture and color to our beds and are fabulous fillers for small, tight areas. But, you know how I feel about Boston fern – please keep it in the pot and do not plant it in the ground here. 

Giant Leather FernGiant Leather Fern

Q: What can you tell me about the giant leather fern?  Can we grow it here?

A:  Giant leather fern, Acrostichum danaeifolium, can indeed be grown here as it is suitable for cold hardiness zones 8b through 12.  Remember we, in Northeast Florida are 8b (west part of the county) – 9a (east part of the county).  It can reach heights upward to 12 feet which is why it gets the name giant fern.  It has been used along retention ponds as it can tolerate fresh to brackish water. This fern can be grown in full sun but will look better in partial shade. Too much sun will cause the edges of the leaflets to turn brown causing people to assume it is dying. Old fronds need to be removed periodically to keep a fresh look.  It also does not tolerate drought well, which means it would need weekly irrigation. 

Resurrection fern

Q: My neighbor wants to cut down here tree because it is covered with a small fern.  She seems to think this means the tree is dying.  Will this fern kill the tree? 

A:   I am so glad you brought in a photo of the fern as this made it very easy for me to identify the fern as Resurrection fern, Pleopeltis polypodioides. This plant is native to Florida and found in moist areas and sometimes on the trunks of trees.  Resurrection fern is classified as an epiphyte, similar to Spanish moss and “air” plants.  It uses the trunk of the tree as a place of attachment but does not derive any of its nutrients from the tree but instead takes moisture and nutrients from the outer surface of the bark.  Because it does not form true roots it must live in areas where the air is continually moist.  The name resurrection comes from the plant appearing to be dead and dried up but once the rains come and moisture returns the plant suddenly comes back to life.  Resurrection fern is not a parasite and it will not kill the tree.  Having Resurrection fern on the trunk of the tree does not indicate the tree is dying or in decline.  However, it does indicate the area is moist and conditions are perfect for the fern to thrive.