Fern Runners: How to Propagate and Care for Them

Fern runners are wiry, leafless stems that creep along or just below the soil surface, sprouting new plantlets at their tips or nodes. They are one of the easiest and most reliable ways to multiply ferns at home, requiring no spores, no tissue culture, and very little special equipment. The process is straightforward once you understand what a runner actually is, which ferns produce them, and what conditions encourage more of them to form.

What Runners Actually Are

If you grow a Boston fern for long enough, you will notice thin, fuzzy stems snaking out from the base of the plant. These are stolons, commonly called runners. They look nothing like the arching, leafy fronds above them, and that contrast is not accidental. Research on Nephrolepis exaltata (the Boston fern) describes the plant as having “extreme stem dimorphism,” meaning it produces two very different kinds of stem: upright shoots that carry the familiar feathery fronds, and horizontal, leafless stolons that spread outward to colonize new ground.¹ The runners have a simpler internal plumbing system than the main shoots, which makes them lighter, faster-growing, and well suited for reaching new patches of soil.

A runner’s job is colonization. Once the tip touches moist soil or another favorable surface, it can root and develop a new rosette of fronds. That new plantlet stays physically connected to the mother plant through the runner, receiving water, sugars, and nutrients through the shared stem until it is established enough to survive on its own. This parent-to-offspring resource pipeline is a defining feature of clonal ferns: the mother subsidizes its daughters until they can photosynthesize and absorb minerals independently.

Which Ferns Produce Runners

Not every fern makes runners. The trait is concentrated in a handful of genera that gardeners encounter regularly:

Nephrolepis (sword ferns): The most prolific runner producers. The Boston fern and its many cultivars send out runners freely. The Dallas fern, Kimberly Queen fern, and other Nephrolepis species do the same, though some cultivars are bushier and less generous with stolons than others.
Davallia (rabbit’s foot ferns): These produce thick, furry rhizomes that creep across the soil surface and over the edges of pots. While technically rhizomes rather than stolons, they function the same way for propagation: they extend outward, root at intervals, and produce new frond clusters.
Salvinia and Azolla (floating ferns): These aquatic ferns spread by fragmentation of connected ramets along branching stems. The growth habit is clonal in the same way as terrestrial runner-forming ferns, though the practical details differ because the plants float.
Pteris (brake ferns): Some species produce short stolons, though less aggressively than Nephrolepis.

The most commonly propagated houseplant ferns by runners are the Nephrolepis species, and the Boston fern in particular is the textbook example. If you have a mature, healthy Boston fern in a hanging basket, you have probably already seen its runners dangling over the pot’s edge, sometimes with tiny plantlets already forming at the tips.

How to Propagate Ferns from Runners

The process is simple enough that it barely qualifies as a technique, but doing it at the right stage makes a noticeable difference in success rate.

When to Take Runners

The best time to separate runners is during active growth, typically spring through early summer. A runner is ready when the plantlet at its tip has developed its own small root system, usually visible as a cluster of white or pale brown roots at least a couple of centimeters long. If the plantlet has only a tuft of tiny fronds and no visible roots, it is too early. You can still propagate it, but you will need to keep conditions more carefully controlled.

The Pinning Method

The gentlest approach is to leave the runner attached to the mother plant and simply pin the rooting tip into a small pot of moist soil placed next to the parent. A bent paperclip, a hairpin, or a small stone works to hold the runner’s tip in contact with the soil. Once the plantlet is visibly growing new fronds on its own, which usually takes two to four weeks, you can cut the runner connecting it to the mother. This method gives the baby fern the best start because it receives parental support throughout the rooting process.

The Cut-and-Pot Method

If the runner already has a rooted plantlet, you can cut it from the parent and pot it directly. Use clean scissors or a sharp blade and cut the runner about five centimeters back from the plantlet, leaving a short stub of runner tissue attached. Pot the plantlet into a small container filled with a light, moisture-retentive mix. Peat-based or coir-based mixes with added perlite work well. Water it in thoroughly and keep humidity high for the first week or two by covering the pot loosely with a clear plastic bag or placing it in a humid room.

Rooting Unrooted Tips

Sometimes you end up with runner tips that have tiny frond buds but no roots. These can still be rooted by treating them like softwood cuttings: press the cut end into moist sphagnum moss or a fine perlite-and-peat blend, keep humidity near saturation, and provide bright indirect light. Success rates drop compared to already-rooted plantlets, and the process takes longer, but it works often enough to be worth trying rather than discarding the material.

Conditions That Encourage More Runners

If your fern is not producing runners, the growing environment is almost always the limiting factor. Research on Nephrolepis exaltata has teased apart the effects of temperature, day length, and light intensity on runner production, and the results are useful for anyone trying to encourage their fern to spread.

Warmer temperatures drive more runner production. In controlled experiments, Boston fern mother plants held at 27°C produced significantly more runners than those kept at 18°C.² The cooler plants did produce runners whose tips were slightly more vigorous when cultured, but the sheer number of runners at the warmer temperature more than compensated. For practical purposes, keeping your fern in a warm room, ideally above 20°C and closer to the mid-twenties Celsius range, will produce more propagation material.

Light matters too. Increased light levels caused an increase in both overall plant growth and runner production.² This does not mean you should blast your fern with direct sun; Boston ferns scorch easily. But the common tendency to tuck ferns into dim corners works against runner production. Bright, indirect light, the kind you get a meter or two from an east- or north-facing window in the Northern Hemisphere, hits the sweet spot.

Day length also plays a role. Runner tips harvested from plants grown under long-day conditions produced more vigorous new shoots than those from short-day plants.² In practice, this means spring and early summer, when days are naturally longer, are the seasons when your fern is most primed to produce and send out strong runners. If you grow under artificial lights, running them for 14 to 16 hours a day can mimic summer conditions.

Caring for the Mother Plant

A fern that is stressed, pot-bound to the point of drying out, or starved of nutrients will produce fewer runners and weaker offspring. The mother plant fuels runner growth from its own reserves, so keeping it in good shape directly translates to more propagation success.

Watering is the most common point of failure. Ferns like consistently moist soil, not waterlogged and not bone dry. The classic advice to “keep the soil evenly moist” is genuinely the right target here. In practice, that means watering when the top centimeter or so of soil feels dry to the touch, and ensuring the pot drains freely so roots are not sitting in standing water. Hanging baskets dry out faster than table pots because air circulates around the entire root ball, so check them more frequently.

Humidity above 50% is important for frond health, but runners themselves are tougher than fronds and tolerate lower humidity. If your fronds are browning at the tips, the air is too dry for the plant to thrive, and runner production will suffer as a consequence of the plant’s overall stress. Grouping plants together, using a pebble tray, or running a humidifier all help.

Feeding during the growing season with a balanced liquid fertilizer, diluted to about half the label rate, every two to four weeks gives the mother plant enough nutrition to produce runners without risking salt buildup. Ferns are not heavy feeders, and overfertilization causes more problems than underfeeding.

How Parent Ferns Support Their Offspring

The runner connecting a parent fern to its offspring is not just a structural tether. It functions as a supply line. Research on clonal ferns has shown that mother plants actively channel resources, including phosphorus and other minerals, to their daughter ramets through these connecting stems. When the parent’s resources are compromised, daughter production drops: stressed parent ramets produce fewer and smaller offspring because there is less surplus to send down the line.³

This has a practical implication for propagation. If you sever a runner too early, before the plantlet has developed enough roots and fronds to feed itself, it loses access to the mother’s support network and may fail to establish. The pinning method described earlier works well precisely because it preserves this connection during the critical rooting phase. Think of the runner as an umbilical cord: cutting it is fine once the baby can breathe on its own, but premature separation reduces survival.

Interestingly, when resources are limited, clonal ferns do not simply reduce output uniformly. They redirect resources among their offspring, diverting more to the most promising growing tip at the expense of secondary ones.³ This means a mother plant with limited energy may funnel everything into one strong daughter rather than spreading itself thin across several. If you want multiple plantlets from one parent, keeping the mother well fed and well lit is the most effective strategy.

Runners Versus Other Ways to Multiply Ferns

Ferns can also be propagated by division, by spores, and in some cases by tissue culture. Each method has a different place in a grower’s toolkit.

Division means physically splitting a mature clump into two or more pieces, each with its own root system and fronds. It works well for clumping ferns that do not produce runners, like maidenhair ferns and many woodland species. For runner-producing ferns, division is still an option but is more disruptive than simply taking runners, and it leaves you with fewer, larger pieces rather than many small plantlets.

Spore propagation is the sexual reproduction route. Ferns produce spores on the undersides of their fronds, and these spores can germinate on moist surfaces to produce tiny intermediate plants called gametophytes, which eventually develop into new ferns. The process is fascinating but slow, often taking six months to a year or more to yield a plant of any real size. It also requires careful sterile technique to prevent mold from overtaking the spores. For most home growers, runners are vastly faster and easier.

There is one important caveat. Many popular Boston fern cultivars are selected mutations that do not come true from spores. The ruffled, compact, or unusually colored forms you see in garden centers were originally found as sports on individual plants and are maintained by vegetative propagation, including runners. If you grew spores from a fancy cultivar, the offspring would likely revert to the plain species form. Runners, being clonal, produce exact genetic copies of the parent, which is why they are the standard commercial method for multiplying named cultivars.

Common Mistakes and How to Avoid Them

A few recurring errors trip up people who are new to fern runner propagation:

Cutting too soon: Separating a plantlet before it has roots is the most common cause of failure. Wait until you can see a small but definite root cluster at the runner tip. If in doubt, leave it attached another week.
Potting into heavy soil: Standard garden soil or dense potting mixes hold too much water around delicate new roots and invite rot. Use a light, airy mix with plenty of perlite or coarse peat.
Letting humidity crash: Newly separated plantlets have tiny root systems and cannot replace water fast enough if the air is dry. A loose plastic cover or a spot in a humid bathroom for the first week or two makes a real difference.
Overfeeding young plantlets: Fertilizer at full strength can burn the roots of a small plantlet. Wait until the new plant has put out several new fronds before feeding, and start at quarter strength.
Ignoring the mother plant’s health: A depleted mother produces weak runners. After taking several plantlets, give the parent time to recover with good light, water, and a modest feeding schedule before harvesting more.

Dealing with Rabbit’s Foot Ferns and Other Creeping Rhizome Types

Davallia ferns, commonly sold as rabbit’s foot ferns, are often grouped with runner-producing ferns even though their spreading stems are technically rhizomes rather than stolons. The distinction matters less than you might think for propagation purposes. A Davallia rhizome creeps along the surface, is covered in soft, furry scales, and produces fronds at intervals along its length. To propagate, you cut a section of rhizome that has at least one or two active growing points (visible as small green bumps or emerging frond tips), pin it onto the surface of moist soil, and keep humidity high. The rhizome roots into the new medium within a few weeks.

The key difference from Nephrolepis runners is that Davallia rhizomes are thicker, woodier, and more self-sufficient. A section of rhizome can survive longer without roots than a thin Nephrolepis runner tip can, which makes propagation a bit more forgiving. On the other hand, Davallia rhizomes grow more slowly, so you get fewer propagation opportunities per year from a single plant.

One thing to watch with Davallia: the creeping rhizomes resent being buried. They are adapted to grow along the soil surface or even over rocks and tree branches. Burying them under soil often causes rot. Pin them on top of the medium and let them root downward on their own schedule. Many growers mount Davallia on slabs of cork bark or in wire baskets lined with sphagnum moss, which gives the rhizomes a textured surface to grip while keeping them exposed to air.

When Runners Become a Problem

In the right climate, runner-producing ferns can become aggressively invasive. Nephrolepis cordifolia, the tuberous sword fern, is a serious weed in parts of Australia, Hawaii, and the southeastern United States. Its runners spread rapidly through garden beds, and it also produces small underground tubers that store water and nutrients, making it drought-tolerant and difficult to eradicate. Each fragment of runner left in the soil can regenerate into a new plant.

Even the common Boston fern, which is less aggressive than its wild relatives, can take over a garden bed in frost-free climates. In containers, this tendency is an advantage: the plant fills out its pot lushly and provides plenty of material for propagation. In the ground in subtropical or tropical regions, it requires borders, root barriers, or regular trimming to keep it from spreading into areas where it is not wanted.

Bracken fern, one of the most widespread ferns on Earth, spreads by deep underground rhizomes rather than surface runners, but the principle is the same: clonal expansion through horizontal stems. Bracken’s rhizomes can extend meters underground, making it extraordinarily difficult to remove once established. Its success across a wide range of elevations and climates is partly due to its ability to produce protective compounds in its fronds that help it tolerate environmental stresses like intense UV light at high elevations.⁴ Bracken is not a fern you would propagate on purpose in a garden, but understanding its aggressive clonal strategy helps explain why runner-producing ferns as a group are so successful in the wild and so easy to multiply at home.