If you want to bring lush, graceful greenery to your porch or patio, learning how to care for Boston ferns outside is the key. These classic plants thrive in outdoor conditions that mimic their native forest habitats, but they do need a specific kind of attention to look their best.
With the right placement, consistent moisture, and seasonal adjustments, your ferns can grow into stunning, full specimens. This guide walks you through all the essential steps, from choosing the perfect spot to helping them survive the winter.
How to Care for Boston Ferns Outside
Outdoor care revolves around three main things: light, water, and humidity. Get these right, and your fern will reward you with vibrant green fronds all season long.
Finding the Perfect Outdoor Spot
Boston ferns cannot handle direct, hot sun. Their delicate fronds will scorch and turn brown quickly. Instead, they need dappled or filtered light.
Look for a location that provides bright shade for most of the day. Ideal spots include:
- Under a covered porch or eave that faces north or east.
- Beneath a pergola with a shade cloth.
- Under the canopy of a tall, open-branched tree.
- In a courtyard that gets only morning sun.
A good test is if you can comfortably read a book in the spot at midday without squinting. That’s the light level your fern wants. Also, choose a place sheltered from strong winds, which can tear fronds and dry the plant out to fast.
Watering Your Outdoor Fern Correctly
This is the most crucial part of care. Boston ferns love consistently moist soil, but they hate sitting in soggy, waterlogged dirt. Their roots need air as well as moisture.
During the hot summer months, you will likely need to water every day, sometimes even twice. Always check the soil first. Stick your finger about an inch into the potting mix. If it feels dry, it’s time to water.
Water thoroughly until it runs freely from the drainage holes. This ensures the entire root ball gets hydrated. Avoid just sprinkling the surface, as this encourages shallow roots. In cooler spring or fall weather, you may only need to water every two to three days.
Tips for Boosting Humidity
Even outdoors, humidity can be low in some areas. If your fern’s fronds look dry or have brown tips, it might need more ambient moisture. Here’s how to help:
- Group your fern with other shade-loving plants. They create a mini-humid microclimate as they release moisture.
- Place the pot on a saucer filled with pebbles and water. Ensure the pot’s bottom is not sitting directly in the water.
- Mist the fronds lightly in the morning with a spray bottle, especially during dry spells.
Feeding for Lush Growth
To support all that beautiful foliage, your fern needs regular nutrients. Use a balanced, water-soluble fertilizer (like a 20-20-20 or 10-10-10 formula) diluted to half strength.
Feed your plant every 4 to 6 weeks during its active growing season, which is from late spring through early fall. Do not fertilize in the winter when growth slows or stops. Over-fertilizing can burn the roots and cause brown leaf tips, so when in doubt, use less.
Seasonal Care and Winter Prep
Boston ferns are tropical perennials (Nephrolepis exaltata) and are not frost-hardy. Temperatures below 55°F (13°C) can damage them, and a freeze will kill them. You must bring them indoors before the first frost in autumn.
- About a month before your average first frost date, start checking for pests. Look under leaves and along stems.
- If you find any bugs, treat the plant with an insecticidal soap or a strong spray of water outdoors.
- Prune away any dead, damaged, or excessively long fronds to tidy up the plant. This makes the transition easier.
- Choose a bright, humid spot indoors, like a bathroom with a window, and acclimate the plant by bringing it in for longer periods each day over a week.
If you live in a very mild climate (USDA zones 9-11), you might try leaving it outside in a protected spot, but be prepared to cover it if a cold snap is forecasted.
Common Problems and Simple Solutions
Even with great care, you might encounter a few issues. Here’s how to fix them.
Brown Fronds or Tips
This is the most common complaint. Causes include:
- Underwatering or low humidity.
- Too much direct sunlight.
- Over-fertilizing.
- Using water with high salt or chlorine content (let tap water sit out overnight before using).
Simply snip off the brown parts with clean scissors, or remove the whole frond at the base. Adjust your care routine based on the likely cause.
Yellowing Fronds
Yellow leaves often signal overwatering or poor drainage. Check that your pot has holes and the soil isn’t compacted. It could also be a sign the plant needs feeding.
The Fern Looks Sparse or Leggy
This usually means it needs more light. Move it to a brighter (but still shaded) location. You can also give it a gentle trim to encourage bushier new growth from the center.
Repotting and Soil Basics
Boston ferns grow quickly and can become root-bound. If you see roots growing out of the drainage holes or the soil dries out extremly fast, it’s time for a new pot.
- Choose a new container only 1-2 inches larger in diameter.
- Use a high-quality, peat-based potting mix that retains moisture but also drains well. You can add a handful of perlite for extra drainage.
- Gently loosen the root ball and place it in the new pot. Fill around it with fresh soil.
- Water well and keep the plant in a shady spot for a few days to recover.
The best time to repot is in the spring, just as new growth begins.
FAQ: Your Boston Fern Questions Answered
Can Boston ferns take full sun?
No. They prefer bright, indirect light or full shade. Direct afternoon sun will burn their leaves.
How often should I water my outdoor Boston fern?
Check daily in summer. Water when the top inch of soil is dry. This often means daily watering in heat.
What’s the best fertilizer for outdoor ferns?
A balanced liquid fertilizer, diluted to half strength, applied monthly during the growing season works great.
Why are the leaves on my Boston fern turning brown?
The most common reasons are lack of water, low humidity, or to much direct sun. Review your placement and watering habits.
Can I leave my Boston fern outside all year?
Only in frost-free climates (zones 9-11). In most areas, you must bring it indoors before temperatures drop near 50°F.
Should I cut off dead fronds?
Yes. Use clean pruners to remove dead or damaged fronds at the base. This keeps the plant healthy and looking tidy.
Caring for a Boston fern outside is a rewarding practice that adds a touch of timeless elegance to your space. By providing filtered light, consistent moisture, and protection from the cold, you’ll be able to enjoy its arching green fronds for many seasons. Pay attention to it’s signals, and don’t be afraid to adjust your routine. With these tips, your outdoor fern will be a thriving centerpiece of your garden oasis.