How to Grow Boston Fern Plants Outside

By Bethany Hayes

One of the easiest plants to identify is Boston ferns. The bright green, lacy foliage stands out against other plants, and they’re a popular choice for indoor and outdoor gardeners. If you want a simple plant to add to your landscaping or container garden, learn how to grow Boston fern plants outside for a bit of character and texture. 

Can Boston Ferns Grow Outside?

Boston ferns are most often grown as a houseplant because these plants prefer growing outside in warm, humid climates. The best USDA zones for Boston ferns are 9-11; these are the only zones where you can plant them outside as a perennial in the ground. 

Anyone can grow Boston ferns outside in containers. You still need to follow the same recommendations as growing them outdoors, but you can bring the plants inside as houseplants for the winter or allow them to die and start a new plant next year. 

If you head to a warm climate, such as Florida, you’ll see hundreds of Boston ferns hanging from balconies. The warm and humidity combination is ideal for these plants. These climates allow these plants to grow for years in these hanging baskets, but gardeners in the North typically only grow ferns in hanging baskets as annuals. 

How to Grow Boston Fern Plants Outside

Whether you’re growing your Boston ferns in a garden bed or a container, you’ll need to follow the same recommendations while growing these plants outside. Here are the basics on Boston fern care outside. 

Find the Right Spot 

Boston ferns prefer to grow in partial or full shade, but dappled, filtered light works as well. If you have any shady, damp areas, Boston ferns are an excellent option to give some color to these areas. That’s why many people grow Boston ferns on covered patios that receive little to no sunlight. 

Preferably, these plants should be sheltered from winds because winds dry out the soil faster. Drying winds mean that you need to water more often, and no one wants to deal with that. 

Get the Right Container 

If you grow ferns in containers and want to put your plant in a new container, move up to a container that is one to two inches in diameter larger than the container it was in at the nursery. 

A self-watering pot is an excellent option because it keeps the soil moist, which is necessary for growing ferns. Another option is to use a plastic pot, which doesn’t cause evaporation as fast. Make sure that the container has drainage holes to prevent the soil from becoming waterlogged. 

Create the Right Soil for Boston Ferns

Whether you use containers or not, these plants prefer a rich, organic soil that is full of nutrients. If your garden soil is low-quality, add several inches of compost, leaf mulch, or finely chopped bark to increase the humus while also ensuring that the soil drains well. 

For container-grown ferns, use a potting soil designed for pots. Peat moss and perlite can be added to the soil to improve airflow to the roots while ensuring proper drainage. Avoid using an excess of peat moss because it can cause your soil to be too acidic. 

Give Plenty of Water

Boston ferns aren’t drought-friendly plants; they need plenty of water to survive. The soil should stay consistently moist but not soggy or waterlogged. Standing water is never a good thing for your plants. Those living in dry climates need to mist their plants on hot days because the humidity is required for proper growth. 

Container grown plants require more frequent watering because the water drains quickly out of the holes. Check your plants daily, and on hot days, check more than once. Boston ferns often need a second watering on sweltering days. 

Over-watering is problematic; it leads to the development of root rot. That can kill your plants. It’s suggested that you should water with lukewarm water.

How do you know if you are watering your ferns properly? 

• If your fern looks paler or starts to yellow, you need to water more. 
• When new fronds appear at the end of spring, increase your watering schedule.
  

Fertilize When Needed

Boston ferns don’t require excessive fertilizers, so you only need to apply occasional applications. Yellowing or pale leaves are indicators that your plant lacks the nutrients necessary for growth. 

If you don’t see these indicators, fertilizing throughout the season is still a smart idea; every six to eight weeks is an appropriate space. Feed the plant with either a water-soluble fertilizer or add a slow-release fertilizer in the spring. 

Watch for Pests

One of the great reasons to grow Boston ferns is that pests don’t bother them too much, but that doesn’t mean they aren’t invulnerable. Some pests enjoy taking a bite out of your plants, and the biggest culprit is slugs.

Slugs are the most common pests that attack Boston ferns growing outside. Inspecting your plants in the morning or evening and removing the slugs by hand is one way to tackle the problem. Sprinkling coarse substances over the soil, such as eggshells or diatomaceous earth, is another solution.

Repot When Needed

As your plants grow and get larger, you will need to repot your ferns if you grow them in a container. When repotting, make sure your new pot is only one to two inches larger in diameter than the current pot. 

Don’t get a much larger pot than your current one because the excess potting soil could cause too much moisture retention that leads to root rot. 

If you’re using a previously used container, be sure to clean out the pot with hot water and soap. Bacteria live in old containers, and you don’t want to infect your healthy fern plant. 

Propagate by Division 

You can propagate Boston ferns by root division. Dividing your fern is an essential step because ferns can become pot-bound or root-bound, making it hard to keep your plant watered. When the roots fill the pot, you can divide your fern and repot half of it elsewhere. 

Spring is the best time to divide your plants, as well as repotting. First, let the soil dry out and remove the plant from its pot. Using a serrated knife, cut the roots apart. Plant each of the divisions into a new pot with fresh potting soil amended with compost and water deeply to help the roots establish in their new home. 

Prune Your Outside Boston Ferns 

When you grow Boston ferns outside all summer, you might notice some shriveled, brown, or discolored leaves. Like many plants, ferns need to be pruned. Pruning gets rid of the fronds that are drying or discolored. It’s like giving your plant a good haircut, trimming off dead ends. 

Ferns handle hard prunes well, leading to bushier, healthier growth. If you want to prune your Boston ferns hard, cut off all of the old-growth in the early spring before it comes out of dormancy. Soon, your plant will be lush and full of new fronds. 

Overwinter Boston Fern Plants

Most people toss out their Boston ferns when the weather gets colder, but that’s wasteful and unnecessary. Ferns can continue to grow for years if you properly overwinter them. 

The first step is to find the best location to overwinter Boston ferns. Bringing your plants inside can be problematic if your house is too hot and dry. Temperatures shouldn’t exceed 75℉, and ferns need high humidity levels when kept as a houseplant. 

If the inside of your house doesn’t provide the right conditions, allow your ferns to go dormant and store them in your garage, basement, or outdoor building where the temperatures don’t dip below 55℉. Taking care of a dormant Boston fern is no big deal. Make sure there is no light accessing the plant; they’re sleeping! Keep the plant thoroughly watered, but limited. That means watering once or twice per month. 

Overwinter Boston Ferns Outside

If you live in a subtropical zone that doesn’t frost or have freezing temperatures, overwintering Boston ferns outside is possible. Only those living in USDA zones 8b-11 can attempt to do so without killing their plants. 

Here are some suggestions for keeping your Boston fern outside in the winter. 

• Prune Your Plants

It’s best to prune your ferns before wintertime. Leave only newly sprouted fronds on your plant; this is especially true if you bring your plant inside because it prevents your plant from dropping all of its old leaves.

• Don’t Move Abruptly 

If you decide you want to move your plant’s location, don’t do so abruptly. Environmental changes need to be gradual. 

• Stop Fertilizing

Don’t fertilize Boston ferns throughout the winter. Resume feedings and regular watering when new shoots appear in the soil. 

Enjoy Growing Boston Ferns Outside

Boston ferns grow outside well in the right conditions. If you live in the right USDA zones, these ferns can grow all-year-round in garden beds or containers. If you live in colder regions, keep your Boston ferns in containers so that you can move them into a sheltered location in the winter months. It’s not as hard as you might think!

Learn More About Growing Boston Ferns

• https://mrec.ifas.ufl.edu/foliage/folnotes/bostonF.htm
• https://extension.uga.edu/publications/detail.html?number=B737&title=Growing%20Ferns