Ferns look lovely indoors, but they can be fussy to grow. Whats the secret of success?
Scientists tell us that ferns have been around for as long as 400 million years. Eons ago, before much of anything interesting existed, ferns covered much of the prehistoric terrain. Along with club moss, horsetails, and other old plants, ferns grew, died, and broke down, making a cycle that may have helped rich coal deposits form later on.
Because they were hardy and adaptable, ferns evolved in all but the world’s most hostile climates. Along the way, many different kinds showed up. Some liked water, while others grew on other plants and got their food and water from the air and rain.
More than 10,000 species of ferns have been identified, and many more await discovery. Approximately 200 species, including the familiar Christmas fern, still populate the temperate areas of the United States.
Prior to the 18th century, naturalists knew little about the intimate activities of ferns. Spores had nothing to do with reproduction, and since no one had ever seen a seed, people thought ferns had supernatural powers.
Ferns are graceful ornamentals that add vibrant green foliage and natural texture to indoor spaces. But nothing mars a fern’s beauty faster than its fronds turning yellow. This troubling color change usually indicates an underlying problem. By identifying the specific cause, you can restore your fern to its former verdant glory.
Overwatering
The most common culprit behind yellowing ferns is overwatering. Ferns prefer an evenly moist soil environment. Too much water saturates the soil, depriving roots of oxygen. It also encourages fungal root rot that damages the root system. With compromised roots unable to take up nutrients the fronds respond by turning yellow.
Check that your fern’s soil is fast-draining and not staying soggy between waterings. Water only when the top inches become dry. Pour water until it flows from the drainage holes, then empty any excess from the saucer. Allowing a fern to sit in water invites decay.
Underwatering
While overwatering is more prevalent, underwatering can also cause yellow fronds. If the soil dries out too much between waterings, the fern becomes stressed and unable to transport nutrients. Leaves first turn light green, then yellow and dry out.
Monitor soil moisture closely and water ferns before the soil dries out entirely. The soil should never be bone dry nor stay saturated. Lifting the pot provides a quick moisture check – the weight changes as the soil dries out.
Excess Light
Too much light burns a fern’s delicate foliage. Direct sunlight scorches the fronds, causing yellowing or browning. Bright, unfiltered light also bleaches the chlorophyll from leaves, giving them a faded yellow appearance.
Position ferns where they get bright but indirect sunlight. Sheer curtains or a frosted window filter the harsh rays. Rotate the plant occasionally since ferns grow towards the light source. If possible, provide shaded outdoor time in summer.
Low Humidity
Humidity is another critical factor for lush ferns. In dry indoor air, the leaf edges often first turn yellow then brown. Mist ferns daily or place the pots on pebble trays to increase local humidity.
Group ferns together to mutually boost humidity. Run a humidifier in the room. Enclose small ferns within open terrariums. Monitor with a hygrometer and aim to maintain at least 50% humidity around ferns.
Nutrient Deficiencies
Like all plants, ferns need a regular supply of essential nutrients. Nitrogen, magnesium, and iron deficiencies most often manifest as yellowing leaves. Insufficient micronutrients hamper chlorophyll production and photosynthesis.
Use a balanced liquid fertilizer every 2-4 weeks during spring and summer when ferns actively grow. Avoid overfertilizing as excess salts can burn tips. If soil nutrients are depleted, repot ferns in fresh potting mix.
Pests
Spider mites, scale, and mealybugs infest ferns and suck nutrients from foliage. Heavy infestations cause stippling damage and yellow spots. Inspect closely for cottony webs, bumps on stems, and tiny insects on leaf undersides.
Isolate and treat infested plants immediately. Remove pests with a strong spray of water every few days. Apply natural pesticides like neem oil or insecticidal soap sprays. Ensure good air circulation and keep humidity levels low to deter pests.
Cold Temperatures
Chilly temperatures shock ferns adapted to warm, humid tropical forests. Prolonged exposure to temps below 50°F causes the tips to yellow and eventually turn brown. Keep ferns away from cold drafts. Move outdoor container plants indoors before first frost.
Place portable heaters or heating mats nearby ferns in winter. Avoid setting heaters too close which creates hot, dry air. Insulate window glass near ferns to reduce cold radiating indoors.
Root Problems
Trouble below ground also manifests through yellowing fronds above. When ferns become severely root bound in a small pot, nutrients cannot be absorbed properly. Root rot from overwatering murders roots. Repot promptly into fresh, well-draining soil.
Remove the fern gently from its pot. Trim off dead roots and comb out the remaining root ball. The new container should be 2 inches wider than the old pot. Use sharp shears to remove any yellow fronds after repotting.
Transplant Stress
Ferns dislike having their roots disturbed. Repotting or dividing plants inevitably causes some transplant shock. Yellowing of older fronds often results as the fern copes with the stress. While largely unavoidable, take care to minimize root damage.
Water thoroughly after repotting and provide ideal growing conditions. Trimming off the most affected fronds focuses energy on new growth. Give the fern time to settle and establish regrowth before fertilizing.
Preventing Yellow Ferns
While the causes vary, avoiding a yellow fern is easier with proper care. Water when just the topsoil is dry. Mist often and fertilize monthly. Provide bright indirect light and night temps above 55°F. Repot before roots bulge from drainage holes. Inspect regularly for pests. By promptly addressing issues, you can nurture a healthy emerald jewel.
The vibrant green fronds of a fern bring beauty indoors. But when those delicate leaves instead turn yellow, it signals trouble. Review the common culprits like overwatering, low humidity, and pests. Take corrective action to restore your fern’s graceful greenery once again. Your indoor garden will thank you!
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Ferns look lovely indoors, but they can be fussy to grow. Whats the secret of success?
Scientists tell us that ferns have been around for as long as 400 million years. Eons ago, before much of anything interesting existed, ferns covered much of the prehistoric terrain. Along with club moss, horsetails, and other old plants, ferns grew, died, and broke down, making a cycle that may have helped rich coal deposits form later on.
Because they were hardy and adaptable, ferns evolved in all but the world’s most hostile climates. Along the way, many different kinds showed up. Some liked water, while others grew on other plants and got their food and water from the air and rain.
More than 10,000 species of ferns have been identified, and many more await discovery. Approximately 200 species, including the familiar Christmas fern, still populate the temperate areas of the United States.
Prior to the 18th century, naturalists knew little about the intimate activities of ferns. Spores had nothing to do with reproduction, and since no one had ever seen a seed, people thought ferns had supernatural powers.
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