Providing form and texture, ferns are easy to grow and make ideal foliage plants for a shady spot. Their unfurling new growth can be delicate and feathery or large and lush, ensuring there are ferns to suit every style and size of garden.
Ferns are a diverse group of plants that have been around for over 300 million years. With over 10,000 species, ferns can be found growing in a wide range of habitats around the world. But when it comes to growing ferns in your own garden, one question often arises – do ferns need acidic soil? This article takes an in-depth look at fern soil preferences to help you understand what conditions are ideal for healthy fern growth.
Examining Fern Soil pH Preferences
The majority of ferns grow best in slightly acidic soil conditions. A pH between 5.5-6.5 is preferable for most ferns. However some ferns can tolerate a wider pH range from 5.0-7.0. Very few ferns actually require strongly acidic soils below pH 5.0.
On the opposite end of the spectrum, certain ferns prefer more alkaline soils above pH 7.0. Examples include maidenhair ferns, hart’s tongue fern, and ebony spleenwort. But these are the exception – acidic soil tends to be the norm for optimal fern growth.
Here’s a quick rundown of soil pH guidelines for ferns
- Most ferns favor slightly acidic soil, pH 5.5-6.5
- Some ferns tolerate a wider pH range of 5.0-7.0
- Very few ferns need highly acidic soil below pH 5.0
- A small number of ferns prefer alkaline soils above pH 7.0
While soil pH does play a role, it’s also important to note that drainage and moisture play a huge role in fern health. Many ferns demand moist, humid conditions. Ensuring proper drainage prevents ferns from becoming waterlogged.
Why Do Ferns Tend to Prefer Acidic Soil?
Over millions of years, ferns evolved and adapted to grow best in forest environments. The slightly acidic soil conditions found in woodlands suit the needs of most ferns very well.
The acidic soil provides ideal nutrient availability for healthy fern growth. The lower pH releases micronutrients like iron, manganese, zinc, copper and boron from the soil. Ferns can then readily absorb these minerals through their roots.
Acidic soils also contain lower levels of calcium, which can be toxic to ferns when present in excess. The reduced calcium in acidic conditions prevents fertilizer burn.
Finally, acidic soils help suppress weed growth that could otherwise compete with establishing ferns. Taken together, these factors explain why most ferns evolved a preference for acidic soil mimicking their native woodland habitats.
How Acidic Does the Soil Need to Be?
Aim for a soil pH between 5.5-6.5 to accommodate most ferns’ preference for slightly acidic conditions. This pH range provides the right balance of nutrients without getting too extreme.
For ferns that tolerate a wide pH range, aim for pH 5.0-7.0. Just avoid drastic pH fluctuations within this range.
Only highly acid-loving ferns like Christmas fern and hay-scented fern demand more extremely acidic soils down to pH 5.0. Woodland natives like these require soils mimicking their natural forest environment.
On the other end of the spectrum, the few alkaline-loving ferns will need pH above 7.0. But the vast majority of ferns will thrive right around the pH 5.5-6.5 sweet spot.
Achieving the Proper pH for Your Ferns
Test your soil’s pH annually to ensure conditions remain ideal for your ferns. soil testing kits are available at garden centers.
Here are some tips to modify soil pH for ferns:
-
To lower pH, mix in elemental sulfur, peat moss, pine bark or pine needle mulch. Good for acid-lovers.
-
To raise pH, incorporate wood ash, limestone or crushed oyster shell. Targets alkaline-loving ferns.
-
Work amendments into the top 3-6 inches of soil before planting.
-
Re-test pH after adjusting to confirm the desired range.
-
Moderate pH over time with organic matter instead of drastic inputs.
-
Ensure proper drainage regardless of pH targets.
Group ferns with similar needs together in beds tailored to their preferred pH range for healthy growth. Avoid planting acid-lovers alongside lime-loving ferns in the same bed.
Signs of Improper pH for Ferns
Monitor ferns for signs of incorrect soil pH:
-
Poor or stunted growth
-
Yellowing of new fronds
-
Smaller fronds than expected
-
Failure to thrive or spread
-
Inadequate moisture and nutrients
-
Increased susceptibility to diseases
-
Leaf scorching or browning at tips or edges
These issues signal it’s time to re-test and adjust soil pH to better match your ferns’ requirements.
Provide Proper Care for Healthy Ferns
While soil pH is important, also be sure to give ferns the following care:
-
Rich, organic matter to mimic forest floor conditions
-
Consistent moisture through rainfall or irrigation
-
High humidity around fronds
-
Filtered light or dappled shade to avoid full sun
-
Protection from strong winds
-
Space for air circulation between plants
-
Division every 3-5 years to maintain vigor
Meeting these cultural needs along with an optimal soil pH will keep your ferns thriving. Select ferns suited to your growing conditions for success. With a little trial and error, you can create just the right habitat for magnificent ferns tailor-made for your unique garden environment.
Key Takeaways on Fern pH Preferences
-
Most ferns grow best in slightly acidic soil from pH 5.5-6.5.
-
Drainage and consistent moisture are just as important as soil pH.
-
Acidic soils provide ideal nutrition and suppress weed growth.
-
Only some rare ferns require highly acidic soils below pH 5.0.
-
A few ferns actually prefer alkaline soils above pH 7.0.
-
Test soil pH annually and gradually amend to fit your ferns.
-
Group ferns in beds with similar pH needs for healthy growth.
-
Monitor for signs of incorrect pH like yellowing fronds.
-
Adjust soil pH while also providing proper cultural care.
-
Select ferns suited to your garden’s conditions for success.
With the right soil pH and care, you can create a lush landscape brimming with diverse fern varieties. They may have prehistoric origins, but their graceful beauty is timeless when planted in suitable habitat that caters to their acidic soil-loving nature.
Where to get ideas and advice
To explore and narrow down your potential planting choices, you can:
- Visit gardens that feature lots of ferns and see which ones you like best. Woodland gardens are often a good choice, especially in spring when ferns are unfurling their new fronds
- All the RHS Gardens feature ferns, and all the plants are labelled, so you can note down your favourites
- Ask at nearby garden centres, which should offer a range of ferns that do well in your local conditions
- Go to RHS Find a Plant and search for ‘ferns’ to browse the photographs and plant descriptions, and find out where to buy them
- Visit a specialist nursery, in person or online
Ferns are best planted in spring or autumn, as this gives them time to settle in before any extremes of hot or cold weather.
Most ferns are woodland plants that like light or dappled shade. They can usually tolerate some sun, as long as they have plenty of moisture.
Ferns like soil that is rich in organic matter, such as garden compost or leafmould. Most prefer neutral to alkaline soil – see how to test your soil – but a few need acidic conditions. They usually prefer plenty of moisture, but not waterlogging, although certain types will tolerate either very wet or dry soil.
Ferns can also be grown in large containers. 
Growing plants in containers
Growing plants in containers
Shade planting: annuals, bulbs and perennials
Shade planting: annuals, bulbs and perennials
Most of the ferns readily available to gardeners are hardy, which means they will survive cold winters outdoors (check plant labels before buying). However, you may find some half-hardy or tender ferns on sale. These need to be kept frost-free over winter, so are best planted in containers that can be moved indoors.
Tree ferns are not fully hardy, so give them a warm, sheltered spot. Larger specimens, with the growing point higher off the ground, may survive outside over winter if protected with straw or fleece, especially in milder parts of the UK. It’s best to bring smaller tree ferns indoors over winter.
Dig in plenty of organic matter such as garden compost or leafmould to improve the soil structure and hold in moisture. This is particularly important when planting under trees, where the soil can be poor and dry.
Ferns are easy to plant and should settle in quickly. They are perennials, meaning they live for several years, and should be planted in the same way as most other container-grown perennials – see our guide to planting perennials.
You can also plant ferns in large containers, either singly or with other shade-loving plants. It’s simple and takes little time – see our guide to planting up containers. Ideally use a mix of three parts peat-free multipurpose compost, one part John Innes No.3, and one part horticultural grit by volume. Ongoing care
Water newly planted ferns regularly for at least their first year. After that, most will only need extra water during long dry spells. Be sure to direct the water to the roots and not onto the fronds or crown, as this can encourage rot.
Ferns in containers should be watered regularly during the growing season aiming to keep the compost moist but not soggy, and especially in hot weather.
Those in very dry soil beneath trees may also benefit from additional watering in summer.
Tree ferns need damp conditions and will not survive drying out, so spray the trunk with water regularly, especially during hot or dry spells. 
Video guide to efficient watering
Video guide to efficient watering
Most ferns planted in the open garden need no additional feeding, but if soil conditions are particularly poor, you could add a well-balanced fertiliser, such as Growmore or blood, fish and bone, in spring.
Apply a mulch of garden compost or well-rotted manure to the soil surface annually in spring, to enrich the soil. Ferns in containers should be given a general fertiliser, such Miracle-Gro, during the growing season.
Tree ferns will benefit from a liquid feed applied monthly to the trunk, in spring and early summer, or a controlled-release fertiliser scattered around the base in spring.
Fertilisers
Fertilisers
Most ferns form quite a dense clump, which hinders weed growth. Mulching around the base with garden compost in spring will help to deter the germination of annual weeds. 
How to identify common weeds
How to identify common weeds Pruning and trainingSimply snip off any dead or ragged fronds before the new crosiers (leaf buds) start to unfurl in spring. Cut them off at the base with secateurs or snips, taking care not to damage any newly developing fronds. Clear away the debris to encourage good air circulation.
After removing the old tattered fronds, chop them up and add them to your compost bin. You can then use the resulting compost as a mulch around your ferns. Propagating
The easiest way to propagate ferns is by division. There are two main methods, depending on how the fern grows.
Getting the right look
Consider what you want from your plant, such as:
- Size – most ferns reach 60cm-1.2m (2-4ft) tall, with only a select few being smaller or significantly taller
- Shape – you can choose from bold, vertical growth or low arching fronds, or anything in between. The fronds can be densely packed, or light and airy, and are often intricately toothed, lacy or feathery, but can also be tufted, ruffled or curly
- Evergreen or deciduous – do you want foliage all year round (evergreen) or from spring to late autumn (deciduous)? Some
Deciduous refers to plants (mainly trees and shrubs) that lose their leaves seasonally, usually during autumn. This is a natural process triggered by the seasons shorter days and lower temperatures and allows plants to conserve energy during the winter months. deciduous ferns turn attractive coppery shades in autumn
- Colour – you can choose from foliage in every shade of green, as well as tinged with purple, pink, silver or bronze. The stems can be also be various colours, including coppery or dark purple
- Style – do you prefer the natural look of
A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since. native British ferns such as Blechnum spicant, or something more exotic, such as a Japanese painted fern or a tree fern?
7 Best Plants That Grow Well in Acidic Soil // Acidic Soil? No Problem!
FAQ
How do I make my soil more acidic for ferns?
Add Sulfur
Sulfur will take some time to lower the soil pH, so it should be added the year before you want to plant. It’s the best option because it lasts for years in the soil and does a better job of acidifying than most other amendments.
Why do you put Epsom salt on ferns?
Super-short science lesson: Epsom salt contains high levels of the micronutrients magnesium and sulfur, essential elements for plants that help them grow, produce more flowers, and increase chlorophyll production (which makes them greener!).
What is the secret to growing ferns?
… to provide ferns with plenty of humidity, generous watering, lots of space, sufficient light without direct sun exposure, and rich, well-draining soilOct 24, 2019
Do coffee grounds help ferns?
-
Nutrient Source:Coffee grounds are a natural source of nitrogen, potassium, and other beneficial nutrients that can contribute to healthy fern growth.
-
Soil Improvement:They can improve soil structure and water retention, which is beneficial for ferns that thrive in moist environments.
-
Compost Ingredient:Coffee grounds are a popular ingredient in compost piles, which can then be used to enrich the soil for ferns.
Do ferns like acidic soil?
Most of the ferns like acidic soil. Ferns exhibit the best growth in the acidic to neutral soil. pH from 4.0 to 7.0 is suitable for the fern to grow. Though ferns like acidic soil, some ferns such as maidenhair ferns prefer alkaline soil in order to grow. Most of the ferns like acidic soil. Soil pH ranges from 2 to 6 is termed acidic soil.
What is the pH of soil for ferns?
Ferns generally prefer shady gardens with acidic soil. It is considered neutral if the soil has a pH of 7. A pH below 7 is acidic, while a pH above 7 is alkaline. The acidic-alkaline range has specific soil pH requirements for different types of ferns. Soil pH is measured in parts per million (ppm).
Can ferns grow if soil pH drops?
Though ferns prefer slightly acidic soil, ferns can’t grow if the soil pH drops drastically. Coffee grounds make the soil drastically acidic. Ferns can’t tolerate such acidic soil conditions and the growth of the ferns drastically decreases.
Do Boston Ferns prefer acid or alkaline soil?
Boston fern prefers acidic soil. Boston fern grows best in the low pH condition ranges from 5 to 5.5. Boston fern is also named the royal fern as they grow in lower pH conditions. Do ferns prefer acid or alkaline soil? Do ferns tolerate acidic soil? Most of the ferns prefer slightly acidic to neutral soil.
Can ferns grow in alkaline soil?
If the soil is too alkaline, gardeners can add sulfur or sphagnum moss to lower the pH. If the soil is too acidic, they can add lime to raise the pH. In addition to adjusting the soil pH, gardeners should also pay attention to the other soil conditions that ferns need to thrive. These include good drainage and plenty of organic matter.
What kind of soil do ferns need?
Ferns need a soil that is high in organic matter and has a lot of nutrients to remain healthy. Ferns do not like standing water, so a soil that easily drains water is necessary. Ferns thrive in acidic soil, so it’s best to use a soil with a pH of 5.5-6.5. Ferns need a soil that is not too fine, as this will not allow for good aeration and drainage.