Blechnum 'Silver Lady' Ferns

Blechnum gibbum 'Silver Lady'.

(Some sources state that the species was reclassified as 'Oceaniopteris gibba' in 2016; however, this isn't an accepted name according to Kew Science). 

Contents

1. Top Tips
2. Location, Water, Humidity & Fertilisation
3. Common Issues
4. Origins, Temperature, Propagation, Repotting & Toxicity.

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Top Tips & Info

• Care Difficulty - Moderate 
• Provide a bright, indirect location with adequate humidity and air circulation. We'd recommend introducing a pebble tray for those situated in dry air below 40%.
• Keep the soil evenly moist, allowing the top third to dry in between waters. Periods of droughts will result in the browning or yellowing of foliage that'll take months to rectify.
• Fertilise using a 'Houseplant' labelled feed every four waters in the spring and summer, reducing this to every six in the colder months.
• Repot every three years with a 'Houseplant' labelled compost in the next sized pot; this is the perfect time to perform basal offset cuttings as seen in the 'Propagation' section.

Location & Light - 🔸🔸

We'd recommend locating your Silver lady Fern in a location that promotes good levels of indirect light and humidity. The ideal site would be within two metres of a north or east-facing window, along with the light being able to penetrate the compost to alleviate the risk of soil mould.  Prolonged exposure of the sun's rays will result in severe dehydration and bleaching, and for information regarding the rejuvenation of crispy specimens, scroll down to the "Common Issues' section now!

Water - 🔸🔸

Allow the soil's top third to dry out in between irrigations, reducing this slightly further in the autumn and winter. Do not, under any circumstances, promote periods of droughts due to the species' reduced ability to endure dehydration. Symptoms of under-watering include crispy or greying of leaves, little to no growth and brown patches forming on the fronds. Since the foliage has a bluish-grey tinge, under-watering symptoms are typically masked until it's too late. Over-watering symptoms include yellowed fronds, rotten rhizomes and a general decline in health. These issues are commonly the product of too little heat or light, waterlogging or an overly-large pot used during the repotting process. 

Humidity - 🔸🔸🔸

Moderate to high humidity should be at the forefront of a Silver Lady Fern. Introducing a pebble tray will not only keep the leaf-tips from browning over, but it'll also slow the risk of drying soil and potential dehydration. A gentle monthly hose-down in the shower will also benefit the specimen, as it'll hydrate the leaves and reduce dust particles resting on its foliage.

Fertilisation - 🔸🔸

Feed every four waters during the growing period and every six in the autumn and winter, using a 'Houseplant' labelled fertiliser. Never apply a 'Ready to Use’ product into the soil without a pre-water first, as it may burn the roots and lead to yellowed leaves.

Common Issues with Silver Lady Ferns

When any fern is severely dehydrated, most of its fronds will yellow/brown and crisp-up - leaving you with a naked plant. Although it may spell the end of juvenile plantlets, there may still be light at the end of the tunnel for more established specimens. Keep the soil continually moist, providing a good level of indirect light and temperatures above 15°C (59°F). After a few weeks, new life will form in the nodal junctions in the plant's centre, signalling the start of its recovery process. For the prevention of dry air, be sure to introduce a humidity tray for higher levels of atmospheric moisture around the foliage. Not only will this ease the specimen back into healthy functioning life, but it'll also reduce the rate of transpiration (water-loss in the leaves), and therefore downplay the risk of dehydration and further decline.

An under-humid room will not favour them in the slightest. Humid air and an absence of dry soil are what keeps this genus happy, so dry air will lead to browning leaf tips and weakened growth. Either mist weekly or introduce a humidity tray to keep life manageable. Avoid situating any fern within four metres of an operating radiator, as the dry air will spread up the process of browning leaf-tips.

Due to the fern's sensitivity to chemicals, Leaf Shine shouldn't be used to improve the appearance of the foliage, and instead should be cleaned using warm soapy water. Failure to do so may cause yellowed, mottled spots that cannot be undone.

Black roots are natural for Silver Lady Ferns. Only treat for root rot if the soil smells 'earthy' and the roots feel collapsed or squishy. Click on this link to learn about this issue and what to do next!

Sudden crispy, grey or wilted foliage shortly after being repotted is a symptom of transplant shock. Increase the humidity around the plant, maintain evenly moist soil and feed every third water with a 'Houseplant' labelled fertiliser. Your Silver Lady Fern is wilting due a damaged root system that doesn't uptake enough moisture to keep its foliage hydrated. Wrap the plant (& its pot) in a transparent plastic bag and check for drying soil. Provide a bright, sunless windowsill with temperatures above 18 ℃ (64℉) and wait for new growth to emerge in a few weeks. Additional Step: Purchase a 'foliar feed' from a local garden centre and mist the foliage to nourish the plant, thus helping its recovery process.

Yellowing leaves are the result of either over-watering or excess moisture settling on the foliage, typically promoted by dark locations. Instead of pouring water directly onto the foliage, irrigate carefully at the soil line by lifting the greenery at the side to prevent wetting the leaves unnecessarily. Do not to over-water your fern if it's situated in a dark location as the combination of both overly moist soil and improper light will allow Rhizoctonia to develop beneath the soil line. For further information about this disease, click on this link. In some instances, yellowing leaves may be caused by under-watering. If this is the case, and the fern has endured persistent droughts, increase irrigations and avoid direct sunlight at all costs. The time in which it takes the specimen to bounce back solely relies on the cultivation and the quality of its current environment.

Never allow temperatures to dip below 10ºC (50ºF) as irreversible damage will occur in the likes of yellow foliage and weakened health. When this happens, remove the severely affected areas and immediately improve growing conditions - never cut through softened yellow growth, and only around brown, crispy squares. As rehabilitation can take several months because of its slow-growing nature, be sure to provide a stable location with better growing conditions to speed this process.

Mould developing on the soil means two things - too little light and over-watering. Despite the harmlessness of the mould, it'll prove unsightly to most gardeners and is therefore removed once known. To remove, replace the top two inches of the soil for a fresh batch of 'Houseplant' compost. Either increase the amount of light received slightly (no direct sunlight) or decreased the frequency of waters slightly. If yellowing older fronds accompany the mould, you may also have a case of root rot.

Blechnum 'Silver Lady' Ferns are popular among growers due to their easy-natured care requirements. Some garden centres will stock them over the course of the year, but can be purchased online for a relatively cheap price. 

Origins

Jacques-Julien Houtou de La Billardière first described the species in the late 18th century, classifying it under the genus of Blechnum, first penned by Carl Linnaeus. 'Blechnum' comes from the Greek word, blēchnon, whereas the specific epithet of 'gibbum' or 'gibba' refers to the hunched arch of mature fronds in the wild. In 2016, Gasper & Salino reclassified the species into Oceaniopteris, which is a group of ferns predominantly grown around the Pacific islands of easter Australia. Kew Science subsequently declined the move, and the species was reverted back to Blechnum shortly after.

The Distribution of Blechnum gibbum.

Temperature

12° - 26℃   (54° - 78℉)
H1b  (Hardiness Zone 12)  - Can be grown outdoors during the summer in a sheltered location with temperatures above 12℃  (54℉),  but is fine to remain indoors, too. If you decide to bring this plant outdoors, don't allow it to endure more than an hour of direct sunlight a day as it may result in sun-scorch. Regularly keep an eye out for pests, especially when re-introducing it back indoors.

Spread

Up to 0.8m in height and 1m in width. The ultimate height will take between 5 - 8 years to achieve, with several new fronds being developed each season.

Pruning & Maintenance

Remove yellowed or dying leaves and plant debris to encourage better growth and improve the all-round appearance. Pruning must be done with clean scissors or shears to reduce the chance of bacterial and fungal diseases - remember to make clean incisions as too much damage can shock the plant

Propagation

Via Spores & Division. 

Spores (Moderate) - You may have noticed little brown spots under the leaves - those are reproductive spores that can be propagated in the same way as seeds, once matured. These zygotes will develop on the under-leaves of each frond; you'll know when they're ready to be propagated, as they'll brown over and begin to crisp.

1. Choose an appropriate potting-mix; we'd recommend a 'Houseplant' labelled compost as it boasts a good balance of aeration and water retention. Place the soil into a plastic pot (any size is fine) that has adequate drainage holes.
2. Separate the spores from the under-leaves using your hands. If the spores are brown and crispy, but can't be removed, cut the entire frond off. Make sure that the diameter of the pot is wider than the frond's span; however, you can cut the frond (sideways) to fit the desired container better.
3. Place the spores or fronds ON TOP of the compost, making sure that they sit flat against the soil-line.
4. If you've managed to separate the spores, maintain moist soil by misting the top layer every few days. Do not submerge into the compost as this will reduce the rates of success. For those who still have entire fronds, place the foliage on top of dry compost. The dehydration will allow the spores to detach from the leaf, settling on the soil below.
5. Place the potted spores/fronds into a transparent bag and situate it into a bright, indirect location. Provide temperatures above 18°F (64°F).
6. Keep the spores moist, misting the top layer of the soil every few days. The fronds, however, must stay dry until you start to notice missing spores from the under-leaves. Once the majority have detached, discard the frond and begin misting the soil to aid hydration.
7. As long as you provide high humidity (aided by the transparent bag locking in moist air) and good soil moisture, germination should begin. This process can take up to two months, but don't discard until it hits five months of nothingness.

Once the spores have developed their first frond, place them into their own pot to grow. Safely remove the transparent bag and follow the care requirements listed at the top of the article.

Division (Easy) - The best time to divide is during the repotting period. Gently tease away some of the soil, separating a basal offset from the mother plant's base which has a good root system and amount of fronds. Place the separated plantlet in a moist, 'Houseplant' labelled potting mix and avoid direct sunlight with prolonged droughts. Although this method is quite easy, be mindful of transplant shock and do not perform this method if the plant is displaying signs of stress. Always moisten the soil 24hrs before repotting or division to avoid shocking the root systems.

Flowers

True ferns will not flower and instead must be propagated by either spores, rhizomes, plantlets or stems, depending on the species. 

After a few years, your Blechnum Fern will reach maturity and will produce spores across the leaf-undersides. Scroll up to learn about spore propagation. 

Repotting

Repot every three years in the spring, using a 'Houseplant' labelled compost and the next sized pot with adequate drainage. Hydrate the plant 24hrs before tinkering with the roots to prevent the risk of transplant shock. For those that are situated in a darker location, add a thin layer of small grit in the pot's base to improve drainage and downplay over-watering. Click here for a detailed step-by-step guide on transplantation, or via this link to learn about repotting with root rot.

Pests & Diseases

Keep an eye out for mealybugs, aphids, spider mites, scale, blackfly, vine weevils & root mealybugs that'll locate themselves in the cubbyholes and undersides of the leaves, with the exception of the latter two in the soil. Common diseases associated with Silver Lady Ferns are root rot, leaf-spot disease, botrytis, rust, powdery mildew & southern blight - click here to learn more about these issues.

Toxicity

Not known to be poisonous by consumption of pets and humans. If high quantities are eaten, it may result in vomiting, nausea and a loss of appetite.

Retail Locations

Dobbies,  IKEA,  Online Stores.

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