Boston fern
Nephrolepis exaltata, epiphyte, evergreen
Water a Boston fern when the soil is dry a few centimetres down, which indoors means every 4–11 days in summer and every 7–18 in winter. It wants plenty of light but not the hot midday sun, and starts to suffer below 15 °C (59 °F).
Updated 12 October 2026. How we write these pages
Boston fern at a glance
Water, indoors
4–11
days in summer
7–18
days in winter
When the soil is dry a few centimetres down.
Month by month
Minimum temperature
10–15 °C
It starts to suffer between 10 and 15 °C (50–59 °F).
Humidity
It likes humid air.
Cats and dogs
Not toxic to dogs or cats.
Eating a lot of it can still upset their stomach.
Growth
Fast. In the wild it grows on trees.
Repotting
When the roots fill the pot.
Pruning
Remove dead leaves.
Where does your plant live?
Pick its place and see what changes.
What changes
- Indoors, near the window. The light is right, as long as the hot midday sun doesn’t hit the leaves through the glass.
- Indoors, away from the window. With less light it grows more slowly and new leaves come in smaller. If you can, move the pot closer to the window.
- Outdoors, in the shade. This suits it: outdoors, bright shade is the light it likes best.
- Outdoors, in the sun. Full sun scorches its leaves, so move the pot into the shade, at least for the hottest hours.
- Indoors, summer. In July it usually needs water every 4–11 days. Heat dries the soil faster, so feel it more often.
- Indoors, winter, heating on. In January it usually needs water every 7–18 days, and more often near a radiator, because warm air dries the soil.
- Indoors, winter, heating on. It likes humid air, and the heating dries it out. Stand the pot near other plants or on a tray of wet pebbles.
- Indoors, winter, cool room. In January it usually needs water every 7–18 days, and less often in a cool room, where the soil stays damp for a long time.
- Indoors, winter, cool room. It starts to suffer below 15 °C (59 °F), so the room has to stay warmer than that.
- Outdoors, summer. Outside the soil dries faster than indoors, where in July it needs water every 4–11 days, so in the sun feel it often.
- Outdoors, winter. It starts to suffer below 15 °C (59 °F). Bring the pot indoors before the first cold nights.
How often to water a Boston fern
Indoors, month by month. Tap a column.
In October
Every 6–15 days
Usually every 9 days. Feel the soil first, and water when it is dry a few centimetres down.
Every month in a table
| Month | Usually | Usually between |
|---|---|---|
| January | every 11 days | 7–18 days |
| February | every 11 days | 7–18 days |
| March | every 10 days | 6–16 days |
| April | every 9 days | 5–14 days |
| May | every 8 days | 5–12 days |
| June | every 7 days | 4–11 days |
| July | every 7 days | 4–11 days |
| August | every 7 days | 4–11 days |
| September | every 8 days | 5–12 days |
| October | every 9 days | 6–15 days |
| November | every 10 days | 6–17 days |
| December | every 11 days | 7–18 days |
Typical intervals indoors in the northern hemisphere: light, the pot and the season stretch or shorten them. How to tell when to water, with a finger and the weight of the pot.
Soil, propagation and problems
Soil
A free-draining soil: extra water has to leave through the hole, not sit in the pot.
Common problems
The most frequent: Scale insects · Caterpillars · Mealybugs · Slugs and snails · Whiteflies
When you feel the soil, look under the leaves too: pests show up there first.
Boston fern: questions and answers
How often should you water a Boston fern in winter?
Indoors in January, usually every 11 days (between 7 and 18), compared with every 7 in July. The longest gaps run from December to February.
How can you tell when a Boston fern needs water?
When the soil is dry a few centimetres down, not just on the surface.
How much light does a Boston fern need?
Plenty of light, without the direct midday sun, which can scorch the leaves. Indoors it does well near a bright window, and further from the window it grows more slowly.
Is a Boston fern toxic to cats and dogs?
Not toxic to dogs or cats. Eating a lot of it can still upset their stomach.
How much cold can a Boston fern take?
It starts to suffer from the cold somewhere between 10 and 15 °C (50–59 °F). If it spends the summer outside, bring the pot in before nights drop below 15 °C, and in winter keep it away from cold glass and draughts.
When should you repot a Boston fern?
When the roots fill the pot. If needed, the best time is spring, when it starts growing again.
How do you prune a Boston fern?
Remove dead leaves.
How can you tell if a Boston fern is getting too much water or too little?
Too much water often shows as leaves drooping even though the soil is wet and roots brown and mushy, or hollow when squeezed. Too little shows as leaves drooping while the potting mix is dry and leaf edges brown and crisp.
How much humidity does a Boston fern need?
Wants humid air: indoors, keep it away from radiators and close to other plants, or on a tray of wet pebbles.
What soil does a Boston fern need?
A free-draining soil: extra water has to leave through the hole, not sit in the pot.
Which pests and diseases affect a Boston fern?
The most frequent are scale insects, caterpillars, mealybugs, slugs and snails and whiteflies. When you feel the soil, look under the leaves too: pests show up there first.
Read next
Every plant has its own rhythm. LINFA keeps track for you.
It looks at the light where your plant stands, its pot and the season, and tells you when to check it.
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