The Secret to Growing Ferns Successfully Indoors or Outdoors

Ferns are one of the oldest plants in existence. They were around with the dinosaurs and you can still find ferns growing on every continent today.

If you enjoy long walks in nature, hiking, or live in a rural area with a reasonable amount of moisture, you’ve most likely spotted ferns growing all over the place. You probably also know that you can also keep ferns as indoor plants, since they’re incredibly popular.

Ferns are relatively simple to grow, but they do have specific requirements. If you can meet those, you’ll be in good shape. Here’s what it takes:

Propagating Ferns

Before we jump in, there are a few terms you should know. First of all, ferns don’t have leaves, they have fronds. Those fronds are made up of the pinna (the part that looks like a small, individual leaf) and the rachis (the center stem).

When the plant is ready to reproduce, it will form spores all over the undersides of the pinna. These tend to group in clusters called sori.

The stipe is the bit at the bottom of the frond that holds the stem to the roots. Underneath the ground is the main rhizome and the little individual roots. In the spring when new growth emerges, it’s called a fiddlehead. On some species, these are edible.

You can propagate ferns in a few different ways, including by spores or division. If you’d prefer, you can always go the easy route and just buy yourself some pretty specimens. Local nurseries often carry species that are ideal for your particular region.

By Spores

To propagate by spores, you’re going to need to plan well in advance of when you want to plant because the process can take a long time. To collect the spores, go out and snip a few fronds from plants you like (make sure you have permission).

Take a look at the undersides of the leaves to see if the spores are present. You’ll see clusters of brown or bronze raised bumps or lines. You can usually find spores in the late spring.

Lay the fronds on wax paper with the undersides down, and leave them in a warm spot out of direct sun overnight. In the morning, gently tap the fronds on the wax paper and look for the dust left behind. These are the spores.

Combine equal parts peat and potting soil and sprinkle the spores on top. Soak the soil well and sprinkle spores on top. Cover with clear plastic wrap. Place in a warm, dark spot. Keep the soil moist. After a few weeks, you’ll see a green surface form on the potting medium.

This green stuff is water and gametophytes, which contain the sperm and eggs that the ferns need to reproduce. Continue to keep the container moist. Eventually, you’ll see tiny fronds forming. Thin the ferns and allow them to grow a few inches tall before transplanting.

By Division

Propagating by division is easy. All you need to do is find a willing friend or some ferns growing wild (make sure it’s legal to take them). Gently dig down the center of the plant and remove half of the fern. Fill in the hole you left behind with some soil.

Plant the portion that you removed in prepared soil.

Growing Ferns Indoors

Here is a list of some of the most common species of ferns for growing as houseplants:

• Boston Fern (Nephrolepis exaltata)
• Staghorn Fern (Platycerium spp.)
• Maidenhair Fern (Adiantum raddianum)
• Lemon Button Fern (Nephrolepis cordifolia)
• Crocodile Fern (Microsorum musifolium)
• Bird’s Nest Fern (Asplenium nidus)

Soil and Light

Most ferns need well-draining soil that has lots of organic matter. Pick a water-retentive potting medium and be sure that whatever container you use at least one drainage hole.

Ferns are fine in low light or indirect light indoors. Pick a spot near the window, but never expose the plant to direct sun. If you place the fern in direct sun, it will damage it and burn the fonds.

You can also use artificial lights, but don’t place them too close.

Temperature and Humidity

When it comes to temperature and humidity there are a few important things to know about when growing ferns inside as houseplants. Depending on the variety of ferns you purchase, the temperature will be slightly different.

For instance, tropical ferns should have at least 60-70℉. Whereas if you have a fern that likes moderate climates then the temperature can drop as low as 50℉. Some species are perfectly fine in colder temps, too. Luckily, most homes are within the ideal range.

Humidity is also essential for growing ferns indoors. It’s not good for ferns to be in dry conditions for too long. If they dry out the leaves can turn brown and drop off.

Mist your fern regularly or place the pot in a tray filled with pebbles or clay granules and water. You can also group plants or use a humidifier. Alternatively, you can keep your fern in your bathroom where there is always constant humidity.

Watering and Feeding

If you’ve ever paid attention to where ferns grow in the wild, they’re usually in spots that are nice and moist, as well as shady. That means you need to keep your fern houseplants moist.

In summer, you should fertilize the plant every four weeks with a liquid fertilizer. Dilute the liquid with equal parts water, since full-strength fertilizer can damage the root system.

During winter, you won’t have to fertilize the plant at all.

Growing Ferns Outdoors

In their native habitat, ferns usually grow in forests or woodlands. That means they prefer moist soil, dappled or little sunlight, and lots of organic matter. Of course, the type of fern will determine the growing conditions for the plant.

Here are some of the most common outdoor ferns:

• Lady fern (Athyrium fern-female)
• Autumn fern (Dryopteris erythrosora)
• Christmas fern (Polystichum acrostichoides)
• Male fern (Dryopteris fern-mas)
• Japanese painted fern (Athyrium niponicum)
• Maidenhairs (Adiantum spp.)
• Cinnamon ferns (Osmunda cinnamomea)
• Ostrich ferns (Weather in Matteuccia spp.)

Any of these ferns are a great choice for growing outdoors. You will also commonly see bracken ferns (Bracken spp.), though these can become invasive in some regions.

Ferns can survive in a range of conditions, from dry to extremely moist and full sun to full shade.

Most of the time, the best point of the year to plant ferns is in early spring after the last frost.

Soil and Light

There are lots of different options for the fern-lover, but most ferns prefer fairly similar growing conditions.

Almost all ferns should be planted in full to partial shade. They also need well-draining, loamy, loose, rich soil. A mixture of your native soil combined with well-rotted compost and grit is a good choice for growing ferns.

Dig in the compost using a shovel at least 8-10 inches deep into the soil. That way, the nutrients will reach the roots of the fern.

Next, dig a hole as deep as the fern’s root ball and twice as wide. Gently remove the fern from the growing pot and place it into the hole in the ground. Just be sure not to disturb the root system too much.

Temperature and Humidity

There are species that can survive in USDA Growing Zones 2-11. Some survive at -40°F, while most prefer warmer conditions in Zones 5 and up. In other words, you’ll need to check and see what the specific species you’re considering can handle.

If you live in a dry region, you’re going to have some trouble finding ferns that will thrive in your area. Brackens are pretty drought tolerant, especially if they’re growing in a nice shady area, but there might be others available.

If you need a little extra humidity, consider planting near a pond or river, though not where the roots will get wet.

Watering and Feeding

Remember that ferns love water, but they don’t love wet feet. You should be able to stick your finger into the soil and it should feel moist, like a well wrung-out sponge. If it feels drier, add water. If it feels soggy, don’t add water for a few days and then check again.

Most ferns will be fine if they’re soggy for just a few days, but longer than that and you’re inviting all kinds of diseases.

Feed ferns in the spring after the fiddleheads have unfurled with a foliage-focused fertilizer like Neptune’s Harvest Fish & Seaweed Fertilizer.

Potential Pests and Diseases

Luckily, ferns don’t suffer from anything too serious when it comes to pests and diseases. However, there are some insects and other issues that can affect your plant’s health.

Pests

Slugs and snails are a common problem for ferns growing outdoors. Use animal-friendly slug pellets to prevent these insects from devouring your ferns. For more tips on creating a slug or snail-free garden, head to our guide.

You could also find aphids or mealybugs on your indoor plants. These are very common with houseplants, so if you’re keeping your fern in your home it’s best to check your plant for any signs of these pests.

You can use neem oil or horticultural oil to control aphids or mealybugs. Otherwise, you can remove the infected area to prevent them from spreading to more plants.

Fern Diseases

Most of the time, fertilizing your plant too much, or not providing enough water is the primary reason that fronds turn yellow.

Some of the most common diseases to impact ferns are root rot, nematodes, and blight.

Root rot is caused by fungi in the Pythium genus, causing yellowing or brown foliage. Underground, the roots rot away. Treat with a copper fungicide.

While most people are familiar with root nematodes, ferns are impacted by foliar nematodes (Aphelenchoides fragariae). It’s difficult to eradicate them and you can only e certain they’re present by testing the frond (either at home or through your local extension office).

You’ll notice brown or dark green spots that gradually enlarge on the fronds. Discard plants or prune away the infected fronds. Otherwise, just learn to live with the pest.

Rhizoctonia blight (caused by the fungus Rhizoctonia solani) causes brown, irregular spots. These enlarge and merge together. Use a copper fungicide to treat.

Companion Planting

Ferns look beautiful in any garden or home, but they can also make a lovely addition to a group of other plants. If you want to plant ferns near other plants outside then some great companions are astilbe, bugloss caladium, hostas, and barrenwort.

For indoor ferns, avoid mixing them with snake plants, aloe plants, succulents, and peperomia. All of these prefer far drier conditions than ferns do. Calathea, pothos, philodendron, spider plants, and begonias all do well with ferns.

Using Ferns

Outdoors, ferns tend to look best in big clusters of either more ferns or other compatible plants. Imagine a single fern alone in a garden under a tree versus a fern next to several big hostas and a blooming bleeding heart plant. Pretty, right?

Use ferns to fill in low-light areas and northern exposures in your yard. Some species can spread readily, so you can use them to fill in areas that can use a little help.

Indoors, feel free to grow them alone in a pot or bunched together with friends.

In the spring, you can eat the fiddleheads of ostrich and lady ferns. Be absolutely sure you’ve identified the right fern by asking an expert and doing your research. Then, remove a few fiddleheads from each plant.

The heads should be tight and curled up, not loose and opening. You can cook them in butter with some salt and pepper. Delicious!