Caring for Ferns in Summer – How to Keep Them Fresh and Healthy

Warm summer days are wonderful for us, but for ferns, high temperatures can be quite a challenge. These lush, green plants are naturally accustomed to moist, sheltered spots in forests or tropical regions. When the thermometer rises, their roots dry out faster, and their fronds can burn. Fortunately, with the right care, you can keep both your outdoor ferns and indoor ferns healthy and beautiful.

Why ferns struggle in the heat

Ferns love consistent moisture, both in the soil and in the air. However, during warm and dry periods, three things happen that can cause stress:

• The sun evaporates moisture from the soil more quickly, causing the roots to dry out.

• Strong sunlight can damage fronds, leaving yellow or brown spots.

• Dry air (outdoors from heat, indoors from air conditioning) causes the fronds to dry out, making them turn brown and curl more quickly.

By keeping these factors in mind, you can prevent most problems.

Outdoor ferns in summer

Outdoor ferns, such as Dryopteris, Athyrium, or tree ferns (Cyathea and Dicksonia), can handle a warm summer day quite well. However, when temperatures rise above 25°C (77°F), they need some extra attention.

1. Provide shade

Ferns naturally grow beneath the canopy of trees, where they receive filtered light. Make sure they are placed in a spot with morning sun or dappled daylight, but protected from the intense midday sun.

• Is your fern in a border that’s too sunny? Consider using a shade cloth during the hottest days.

2. Smart watering

• In warm weather, it’s better to water twice a day in smaller amounts (early in the morning and late in the evening).

• Keep the soil consistently moist, but avoid letting the roots sit in standing water – this can cause root rot.

• A drip irrigation system in the garden can be ideal for providing a steady, gentle supply of moisture.

3. Protect the soil with mulch

A layer of bark, compost, or leaves around the base of the fern helps retain moisture and protects the roots from extreme heat.

4. Protect the fronds

For some varieties, such as tree ferns, you can gently mist the fronds on hot days. Do this preferably in the early morning so the foliage has time to dry before the sun is directly overhead.

Indoor ferns in warm temperatures

Indoors, temperatures can rise quickly due to sunlight and heat coming through windows. Indoor ferns, such as Nephrolepis (Boston fern), Asplenium (bird’s nest fern), or Adiantum (maidenhair fern), enjoy warmth but thrive best in high humidity.

1. Shelter from direct sunlight

Direct sunlight can scorch the leaves. Place your fern about a metre away from the window, or use a sheer curtain to filter the light.

2. Increase humidity

• Place a shallow dish of water nearby or use a humidifier.

• Group plants together: as they release moisture, they naturally raise the humidity in the surrounding air.

• Lightly mist the foliage from time to time, but avoid the centre of the plant to prevent mould growth.

3. Check the potting soil more often

Warm indoor air causes the soil to dry out more quickly. Insert your finger 2–3 cm into the soil: if it feels dry, it’s time to water.

4. Watch out for air conditioning and fans

Do not place your fern directly in the airflow. This will dry out the fronds and can cause brown edges.

Rainwater: the bonus for healthy ferns

Ferns prefer soft water. Tap water often contains lime (calcium), which can cause leaf damage or discoloration over time. Rainwater is perfect: it’s softer, natural, and usually just the right temperature.

Conclusion

With a little extra care during hot days, your ferns will stay beautifully green and healthy. Keep their natural preferences in mind: filtered light, consistent moisture, and protection from extreme heat. This way, you can create a little tropical forest feeling in your garden or living room even in the middle of summer.