Ferns generally require consistently moist soil but not soggy conditions. The frequency of watering depends on the type of fern, whether it is indoors or outdoors, the climate, and the potting conditions. Indoor Ferns:

• Water when the top inch of soil feels dry, usually about once a week or once every two weeks. In warmer or drier indoor environments, watering may be needed more frequently, up to twice a week

• Boston ferns may need watering every 1–3 days in winter and daily or multiple times a day in summer due to their thirstiness and love for humidity

• Other types vary: Maidenhair ferns may require daily watering, Kimberly Queen ferns every 3-5 days, and Lemon Button ferns about once a week

Outdoor Ferns:

• Outdoor ferns often need watering at least once a week, with more frequent watering during hot, dry weather. Soil should be kept damp but not waterlogged

• In summer, watering every 4-5 days is common, while in winter, intervals can extend to 7-10 days

General Tips:

• Check soil moisture by feeling the soil a couple of inches below the surface; water if it is dry

• Avoid letting soil dry out completely as ferns can crisp up and suffer.
• Overwatering can cause root rot, so ensure pots have drainage and avoid waterlogging

• Misting ferns can help maintain humidity, especially for indoor plants

In summary, water ferns enough to keep their soil consistently moist, adjusting frequency based on season, location, and fern type, typically ranging from daily in hot conditions to once every 1-2 weeks in cooler or more humid environments