Nephrolepis cordifolia aka Boston Fern

Water when the top 1-2 inches of soil feel dry, but never allow the soil to dry out completely. Nephrolepis cordifolia prefers consistently moist, well-drained soil and is sensitive to drought. During the growing season (spring through early fall), water moderately with soft water. In winter, reduce watering slightly but maintain soil moisture. Overwatering can lead to root rot, so ensure good drainage.

Nephrolepis cordifolia thrives in temperatures between 60-80°F (15-27°C), with an ideal range of 65-75°F (18-24°C). It can tolerate brief temperature drops to around 50°F (10°C) but prolonged cold will damage the plant. Keep it away from cold drafts, air conditioning vents, and heating sources. The plant is hardy in USDA zones 8-11 and can be grown outdoors year-round in frost-free climates.

Nephrolepis cordifolia prefers high humidity of 60-80%, though it can tolerate levels as low as 50%. Increase humidity by misting regularly, placing the pot on a tray of wet pebbles, grouping with other plants, or using a humidifier. Low humidity often causes brown leaf tips and crispy fronds. This fern appreciates good air circulation along with high humidity to prevent fungal issues.

Nephrolepis cordifolia can be propagated by division, runners, or spores. The easiest method is division: carefully separate the root ball into sections, ensuring each has fronds and roots, then pot in fresh soil mix. You can also separate rooted runners (offsets that sprout from rhizomes) in late winter or early spring. For spore propagation, sow spores at 21°C when ripe, though this method is more challenging and time-consuming.

Prune Nephrolepis cordifolia in early spring to prepare for new growth. Remove dead, yellowing, or brown fronds by cutting them at the base with clean, sharp scissors or pruning shears. Trim back overgrown fronds to maintain shape and improve air circulation. Regular removal of old fronds keeps the plant neat and healthy. Always sterilize pruning tools between cuts to prevent disease transmission.

Repot Nephrolepis cordifolia every 1-2 years in spring when roots become crowded or grow through drainage holes. The Lemon Button Fern variety (N. cordifolia 'Duffii') grows more slowly and may only need repotting every 2-3 years. Use a pot 1-2 inches larger and a well-draining, porous potting mix—ideally peat-free multipurpose compost or a mixture of 1 part loam, 2 parts sharp sand, and 3 parts leaf mould.

Clean Nephrolepis cordifolia fronds every 2 weeks using a soft, damp cloth to gently wipe both sides of the leaves, or use a soft brush for hard-to-reach areas. Dust blocks sunlight and affects photosynthesis, so regular cleaning keeps the fern healthy. Alternatively, give the plant a gentle shower with lukewarm water. Avoid leaf shine products, which can damage delicate fern fronds and clog pores.

Yellow leaves on Nephrolepis cordifolia typically indicate insufficient light or watering problems. If the plant doesn't receive enough bright indirect light, it can't photosynthesize properly, resulting in pale, yellow, weak fronds. Overwatering or underwatering can both cause yellowing—check that soil is consistently moist but not waterlogged. Other causes include nutrient deficiency (fertilize monthly during growing season) or natural aging of older fronds.

Brown tips on Nephrolepis cordifolia are most commonly caused by low humidity or underwatering. This fern needs 60-80% humidity, and dry air quickly causes crispy brown edges. Other causes include over-fertilizing (use only half-strength balanced fertilizer monthly), tap water with high fluoride or chlorine (use filtered or rainwater), or fronds becoming too wet (which can cause rotting). Increase humidity with a pebble tray or humidifier.

Nephrolepis cordifolia has no significant diseases but can be affected by scale insects, mealybugs, Florida Fern Caterpillar, ants, and slugs. Mealybugs appear as white cotton puffs on new growth and are difficult to treat due to the fern's many crevices—treat with a strong water spray, alcohol on cotton swabs, then neem oil or insecticidal soap. Root rot can occur from overwatering in poorly-draining soil. Generally, this fern is quite disease-resistant with good care.

Popular Nephrolepis cordifolia cultivars include 'Duffii' (Lemon Button Fern)—a compact dwarf with rounded leaves and lemon scent when crushed, growing to about 1 foot; 'Plumosa'—slow-growing with 32-inch arching fronds reaching 3 feet tall and 5 feet wide; 'Kimberly Queen'—enhanced sun tolerance; 'Tessellata'—recognized cultivar; 'Petticoat'—rare variety with fronds forming a petticoat-like shape; and Living Lace® Cute as a Button™—compact dwarf with petite lemon-scented leaves.

Nephrolepis cordifolia can be grown outdoors year-round in USDA hardiness zones 8-11 (frost-free or minimal frost areas). In cooler climates (UK hardiness H1b), it can be moved outdoors during summer months when temperatures stay above 50°F (10°C). Plant in partial shade with well-draining soil, spacing 18 inches apart. Be cautious in warm climates like Florida where it's considered invasive.

The underground tubers of Nephrolepis cordifolia are edible and traditionally eaten in some cultures, particularly in Nepal and the Philippines. The tubers can be eaten raw (tasting sweet, crunchy, and earthy like Jerusalem artichokes) or cooked. Small roots roasted in an oven become sweet and chewy, while large roots can turn powdery. However, this is a marginal food source rather than a cultivated food crop. The fronds are not typically consumed.

In traditional medicine, Nephrolepis cordifolia rhizomes treat rheumatism, chest congestion, and anorexia, while fresh fronds serve as a diuretic, contraceptive, and remedy for fever, coughs, and skin diseases. Scientific research has confirmed antibacterial, antifungal, anticancer (anti-tumor), hepatoprotective, and antioxidant properties in plant extracts. These compounds show potential for cancer chemoprevention. However, these are traditional uses and research findings—consult healthcare professionals before using medicinally.

Beyond ornamental use, Nephrolepis cordifolia serves as an excellent air-purifying houseplant, removing toxins from indoor air. In Hawaiian culture, the fronds (known as kupukupu or ni'ani'au) are traditionally used to make wrist and ankle lei. The compact growth makes it ideal for terrariums and bottle gardens. In landscapes, it provides erosion control on slopes and works well as ground cover in shaded areas. The tubers also store water, helping the plant survive drought conditions.