Boston fern
Nephrolepis exaltata
A fern that drops fronds and sheds crisp leaflets all over the floor in dry air, which is what a centrally heated room provides. In a bathroom, a shaded porch or anywhere genuinely humid it is luxuriant and undemanding, and it is safe around pets.
- Position
- Bright, out of direct sun
- Water
- high demand
- Drainage
- Moisture-retentive
- Grows to
- 40–90 cm × 60–120 cm
- Frost
- Frost tender
- Difficulty
- Some care needed
August
Nothing to do
No sowing, planting, harvesting or pruning window falls in August.
Boston fern’s year
Resolved for United Kingdom (general). Every window is stored against a climate event rather than a date, so a late frost pocket runs later than the band shows. What else August calls for.
| Activity | J | F | M | A | M | J | J | A | S | O | N | D |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Take cuttings | April. | May. | June. |
Timing that travels
The band above resolves this plant's windows into months for one region. These are the windows themselves, stored against a climate event rather than a date — which is the form that survives being carried to a colder garden, a frost pocket, or next year.
Conditions it needs
- Light
- Partial shade, Dappled shade
- Frost
- Frost tender
- Grows best at
- 16–24 °C
- Soil
- Peat-free compost
- Soil pH
- 5.5–6.5
- Drainage
- Moisture-retentive
- Water needs
- high
- Drought
- poor tolerance
- Waterlogging
- moderate tolerance
- Heat
- poor tolerance
- Wind and exposure
- poor tolerance
Where these figures come from
- LightSourced guidancemoderate confidence
- Royal Horticultural Society: Boston fern — position
Checked 2026-08-13
- FrostSourced guidancehigh confidence
- Royal Horticultural Society: Boston fern — hardiness
Checked 2026-08-13
- Grows best atSourced guidancemoderate confidence
- Royal Horticultural Society: Boston fern — temperature
Checked 2026-08-13
- SoilSourced guidancemoderate confidence
- Royal Horticultural Society: Boston fern — soil
Checked 2026-08-13
- Soil pHSourced guidancemoderate confidence
- Plant Finder — Missouri Botanical Garden: Nephrolepis exaltata — culture
Checked 2026-08-13
- DrainageSourced guidancemoderate confidence
- Royal Horticultural Society: Boston fern — soil
Checked 2026-08-13
- Water needsHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- DroughtHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- WaterloggingHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- HeatHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Wind and exposureHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
On your soil
Computed by comparing this plant's recorded requirements against each soil's recorded characteristics. A recorded horticultural fact overrides the comparison where GrowingHQ holds one.
| Soil | Verdict | Why |
|---|---|---|
| Heavy clay | Grows well here | Boston fern grows perfectly well on heavy clay without special measures, though it is not the soil it would choose. |
| Sandy | Struggles here | Included because the record exists and the comparison would otherwise pass it: a Boston fern is a container houseplant and is never planted in garden soil in Britain. Where it does go outside for the summer it wants a moisture-retentive mix, not sand. |
| Chalky and alkaline | Struggles here | Boston fern struggles on chalky and alkaline: The soil is substantially too alkaline for it: it wants pH 5.5 to 6.5, and this soil sits around 7.8 to 8.5. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering. A container or a raised bed of imported soil sidesteps the problem entirely. |
| Loam | Grows well here | Boston fern grows perfectly well on loam without special measures, though it is not the soil it would choose. |
| Silty | Grows well here | Boston fern grows perfectly well on silty without special measures, though it is not the soil it would choose. |
| Peaty and acid | Grows well here | Boston fern grows perfectly well on peaty and acid without special measures, though it is not the soil it would choose. |
| Shallow over rock | Works, with one condition | Boston fern will crop on shallow over rock, but one thing has to be dealt with first. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering.Water and mulch will carry it through. On this soil the watering is not optional in a dry spell, which is the difference between a crop and a failure. |
| Made ground and urban soil | Works, with one condition | Boston fern will crop on made ground and urban soil, but one thing has to be dealt with first. The soil is substantially too alkaline for it: it wants pH 5.5 to 6.5, and this soil sits around 7.2 to 7.8.The pH is the obstacle. Small shifts are achievable and slow; large ones are not. On made ground and urban soil the dependable answer is a container of the right compost rather than an attempt to change the ground. |
Not sure which you have? Four hand tests will settle it.
Space and spacing
- Mature height
- 40–90 cm
- Mature spread
- 60–120 cm
- Rooting depth
- 20 cm
Where these figures come from
- Mature heightHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Mature spreadHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Rooting depthHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
In a container
- Minimum volume
- 4 litres or more
- Minimum depth
- 18 cm
Where the container figures come from
- Minimum volumeHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Minimum depthHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
Where and how you can grow it
Each way of growing is assessed separately, and “not assessed” is a real answer rather than a gap we have filled in with a guess.
| Method | Suitability | What it needs |
|---|---|---|
| Indoor pot | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | High humidity — a bathroom is ideal |
| Container | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | Shade; Indoors, or outside in summer shade |
| Greenhouse | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Windowsill | MarginalsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Hydroponics | Not assessedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Open ground | Not suitablesourceSourced guidancemoderate confidence
Checked 2026-08-13 |
Growing it
- ProtectionPut it somewhere genuinely humid rather than trying to raise the humidity around it. A bathroom or a kitchen works; a pebble tray in a heated living room does not raise humidity enough to matter, whatever is commonly written.
- PruningCut old browned fronds off at the base rather than trimming the ends. New fronds unfurl from the centre continuously, and removing the tired ones keeps the plant looking well without affecting growth.
- WateringThis is the plant on the shelf that must not dry out. Keep the compost consistently moist all year, water as soon as the surface feels dry, and stand the pot on damp gravel — the fronds crisp from the tips inward when the air or the compost is dry, and crisped fronds do not recover and have to be cut off. Reduce a little in winter because it is growing more slowly, but far less than you would for anything else here; the real winter danger for a Boston fern is not the watering can but the radiator underneath it, which dries the air around the plant far faster than the compost. It will not tolerate standing in water either, so drain it properly each time.
- FeedingA half-strength balanced feed monthly from spring to early autumn. Ferns have fine roots that scorch easily, so use it dilute and never on dry compost — water first, feed second. Stop from October. Yellowing, thinning fronds in midwinter are almost always dry air or too little light rather than hunger, and feeding into that produces nothing. Old fronds browning off from the outside of the crown while new ones unfurl in the centre is normal renewal; cut them out at the base.
Where this guidance comes from
- ProtectionSourced guidancemoderate confidence
- Royal Horticultural Society: Ferns indoors
Checked 2026-08-13
- PruningSourced guidancehigh confidence
- Royal Horticultural Society: Ferns — care
Checked 2026-08-13
- WateringSourced guidancehigh confidence
- Royal Horticultural Society: Nephrolepis exaltata — cultivation
Checked 2026-08-13
- FeedingSourced guidancemoderate confidence
- Royal Horticultural Society: Nephrolepis exaltata — cultivation
Checked 2026-08-13
What goes wrong
Start from what you can see
Safety and edibility
Listed as non-toxic to cats and dogs
Boston fern appears on published non-toxic lists for cats and dogs. That is a statement about the plant's chemistry, not a guarantee: any plant eaten in quantity can upset an animal, so it is still worth discouraging heavy chewing.source
Sourced guidancehigh confidence
- ASPCA Animal Poison Control Center — toxic and non-toxic plant list — American Society for the Prevention of Cruelty to Animals: Nephrolepis exaltata — non-toxic plants list
Checked 2026-08-13
- Pets and livestockpetsNot toxic to cats or dogs. One of the safest choices for a household with pets that chew plants.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Nephrolepis — toxicity
Checked 2026-08-13
No particular precautions needed.
Sources for this page
GrowingHQ editorial synthesis · Plant Finder · Royal Horticultural Society
Each figure on this page carries its own citation, under the “where these figures come from” note in its section. Record last reviewed 2026-08-14.
If something is wrong with it
- Growth has stalled — 2 causes GrowingHQ holds for boston fern
- Lower leaves turning yellow — 2 causes GrowingHQ holds for boston fern
Something else? Work through it with the diagnostic tool.