Nephrolepis exaltata, also known as Sword or Boston ferns, are lush, evergreen plants with a maximum height of up to 7 feet when they are grown outdoors. These slow-growing plants require quite a bit of care and attention, so they are usually recommended for intermediate gardeners.
Boston ferns have a height range of 1 – 7 feet tall. Boston ferns that are kept as houseplants will usually grow as tall as 3 feet and can have a width or spread of up to 3 feet as well. Outdoor Boston ferns can grow as tall as 7 feet and usually have an even larger spread.
If you own a Boston fern and are wondering about its growth patterns, then you’ve come to the right place. Our guide on Boston fern growth habits will help you on your way to becoming a certified fern connoisseur.
Boston Fern Growth
Boston ferns are popular plants for houseplant enthusiasts and avid gardeners alike. These versatile plants can be kept both in and outdoors to give your home or garden a lush and unique look.
However, these plants can have very different growth heights and widths, depending on where they’re grown.
Boston Fern Growth Rate
No matter where you plant your Boston fern, you can expect your plant to grow around 8 to 10 inches taller each year during its growing season. Their growth period starts in early spring and continues until the end of the warmer months as summer ends.
Your Boston fern will become dormant during the winter months, so you shouldn’t expect much – if any – growth during this time. But a healthy and happy plant can produce between 10 to 12 new leaves each year.
How Big Do Boston Ferns Get Indoors?
If you’re keeping your Boston fern as a hanging or indoor plant, you can expect your plant to reach 1 to 3 feet tall when it has reached full maturity. Similarly, your plant will have a foliage spread or width of around 2 to 3 feet wide.
How Big Do Boston Fern Get Outdoors?
If you’re growing your Boston fern outdoors, it’s important to note that these plants will only survive and flourish in hardiness zones 9 – 11. But if you live outside of these hardiness zones, you may want to consider growing your fern indoors instead.
When grown outdoors, Boston ferns can reach a height of up to 7 feet and have a much larger width or spread than their houseplant counterparts.
How to Grow Huge Boston Ferns
Growing a large Boston fern requires patience and a lot of care. These plants are relatively slow-growing, so you may need to wait before your fern reaches its full growth potential.
Before growing your plant, you will need to consider its maximum height. If you are growing your fern indoors, you can grow your fern as large as 3 feet tall. But, if you are planting this unique fern outdoors, you may be rewarded with a 7-foot-tall plant after a few years of dedication!
It’s also important to remember that your Boston fern plant may not reach its full growth potential if it is not growing correctly. This fern can be grown outdoors and should flourish in hardiness zones 9 – 11. But if you live outside of these zones, your plant will need to be grown indoors. In that case, your fern will be restricted as to its maximum growth.
The secret to growing larger Boston ferns is knowing how to properly care for your plant, no matter where it’s planted. We’ve put together a simple Boston fern plant care guide to help you on your way to encouraging maximum growth in your plant.
Boston Fern Pots and Containers
Boston ferns will usually only grow as large as their pot or container allows. So, if you want to help your fern grow even bigger, you’ll need to make sure that it is planted in a container with lots of space to grow.
You will also need to repot your plant as soon as it outgrows its current container to encourage even more growth.
Boston Fern Light Requirements
To give your Boston plant the best chance of reaching its growth potential, you will need to ensure that your plant is getting a lot of bright, indirect light. If you’re growing your fern indoors, you should keep it in a room that receives plenty of warmth and sunlight without directly letting the light shine on your plant.
If you’re growing your fern outdoors, you may need to make sure that it receives dappled or filtered shade and that it is partially covered by other plants or trees.
Bost Fern Water Requirements
Boston ferns love warm, humid environments. For this reason, this fern also loves damp soil. You will need to keep the soil moist at all times without letting it become soggy or waterlogged. Over-watered ferns will not be able to grow well, and staying in wet soil for too long can stop your Boston from growing altogether.
Boston Fern Pruning Requirements
Boston ferns absolutely love being pruned! By pruning your plant regularly, you will help to encourage faster growth, making your plant thicker and more voluminous than ever.
For indoor Bostons, you should trim them regularly using sharp gardening shears. You will need to prune any leafless stems and get rid of brown or discolored leaves. You can also cut around the plant to stop overgrowth and to keep it looking neat.
Conversely, outdoor Bostons should be cut to around four or five inches above the ground before their dormancy period. They will begin to grow slowly during the colder months, but your pruning efforts will be rewarded with more extensive, thicker growth in the spring and summer.
Can You Keep Boston Ferns Small?
Boston ferns will only grow as large as their container allows. So, by keeping them in a smaller container, you can keep your fern smaller. However, it’s important to note that you will need to remove your plant from its container to trim its roots back every once in a while.
Trimming the roots of your Boston is essential because, without special care and attention, your plant may fall victim to root rot or other problems. These problems can potentially harm your plant or cause it to wither and die.
Boston ferns are beautiful, relatively slow-growing plants that can be kept indoors and outdoors. As a houseplant, this fern can reach up to 3 feet and have a foliage spread of around 3 feet wide. However, these ferns will flourish outdoors in zones 9 – 11 and can reach massive heights of up to 7 feet!
Growing up with a mom who filled her home (inside and out) with all sorts of plants, Lisa got her start in gardening at a young age. Living now on her own with a home and yard full of plants (including an indoor greenhouse), she shares all the gardening tips she’s gained over the years.