Watering schedule
How often to water Roundleaf Sundew (Drosera rotundifolia) — the schedule
Also called Common sundew.
More about roundleaf sundew
About Roundleaf Sundew
Drosera rotundifolia · also called Common sundew · flowering
Drosera rotundifolia is the temperate roundleaf sundew native to acidic bogs across the Northern Hemisphere. Its flat rosette of round, long-stalked leaves bristles with red, dew-tipped tentacles that trap small insects. Fully cold-hardy, it forms a winter resting bud (hibernaculum) and demands a genuine cold dormancy, pure water, and permanently wet, acidic peat.
Ideal humidity: 50-80%
Watch for — Rot during winter: Standing water on the dormant hibernaculum causes rot. Keep merely damp, not flooded, and ensure airflow over winter.
The watering schedule, season by season
Roundleaf Sundew is a bog plant adapted to nutrient-poor wet ground — it must sit in a tray of pure water and must never get tap water or fertiliser. The base rhythm for roundleaf sundew is keep saturated; stand in 1-3 cm of pure water through the growing season, but the real interval moves with the season, the light and the pot — so treat the figures below as a starting point and always confirm with the plant itself.
- Spring & summer (active growth): Spring and summer: keep the pot standing in 1-2 cm of distilled or rainwater at all times; top the tray up as it is taken up.
- Autumn (slowing down): Autumn: lower the tray water level as growth slows and (for temperate species) dormancy approaches.
- Winter (rest / dormancy): Winter: keep just damp, not flooded — many temperate carnivores need a cool dormancy with far less water.
Rainwater, distilled, or RO only. In winter dormancy keep the peat damp but reduce standing water to avoid rotting the hibernaculum.
Want this turned into a live reminder that adjusts to your home and the weather? The Growli watering calculator takes your pot size, light and season and returns a starting interval for roundleaf sundew in seconds.
How to tell roundleaf sundew needs water
A calendar is the worst way to water roundleaf sundew. Check the plant and the soil instead — for this species, look for these signals in order:
- The tray has run dry (during active growth it should rarely be empty).
- The peat-based medium feels dry rather than wet.
- Traps or pitchers shrivel or fail to form.
The most reliable single check is the first one on that list. When two signals agree, water; when they disagree, wait a day and look again — under-watering roundleaf sundew for a day is almost always safer than over-watering it.
Overwatering vs underwatering roundleaf sundew
The two failure modes can look alike at a glance, so check the soil weight and wetness before you decide. For roundleaf sundew specifically:
Signs you are overwatering
- Blackening traps or pitchers from stagnant, warm, mineral-laden water.
- Rotting crown if kept warm and flooded through winter dormancy.
Signs you are underwatering
- Traps go limp and brown; pitchers dry up.
- The medium dries out and the plant collapses quickly.
Tap or bottled mineral water kills roundleaf sundew. Its roots cannot handle dissolved minerals — only rain, distilled, or reverse-osmosis water will do.
Water quality notes
Only rainwater, distilled or reverse-osmosis water — never tap, mineral or softened water. This is the single most important rule for roundleaf sundew.
Seasonal and environmental adjusters
Every figure above shifts with the conditions in your home. For roundleaf sundew, the levers that matter most are:
- Bright light plus the water tray is the whole game — no fertiliser ever goes in the soil.
- In hot weather the tray empties fast; check it daily.
- Temperate species need a cooler, drier winter dormancy, not constant flooding.
Pot choice is part of this too — work out the right size with the pot size calculator, since a pot that is too big stays wet long enough to rot the roots of roundleaf sundew.
Roundleaf Sundew watering — frequently asked questions
How often should I water roundleaf sundew?
Water roundleaf sundew keep saturated; stand in 1-3 cm of pure water through the growing season. Spring and summer: keep the pot standing in 1-2 cm of distilled or rainwater at all times; top the tray up as it is taken up. Winter: keep just damp, not flooded — many temperate carnivores need a cool dormancy with far less water.
How do I know when roundleaf sundew needs water?
The tray has run dry (during active growth it should rarely be empty). The peat-based medium feels dry rather than wet. Traps or pitchers shrivel or fail to form. The single most reliable test for roundleaf sundew is the first signal on that list — checking the soil or the plant directly always beats watering by the calendar.
What does an overwatered roundleaf sundew look like?
Blackening traps or pitchers from stagnant, warm, mineral-laden water. Rotting crown if kept warm and flooded through winter dormancy. Tap or bottled mineral water kills roundleaf sundew. Its roots cannot handle dissolved minerals — only rain, distilled, or reverse-osmosis water will do.
What are the signs of an underwatered roundleaf sundew?
Traps go limp and brown; pitchers dry up. The medium dries out and the plant collapses quickly.
Can I use tap water on roundleaf sundew?
Only rainwater, distilled or reverse-osmosis water — never tap, mineral or softened water. This is the single most important rule for roundleaf sundew.
Keep reading
- Watering roundleaf sundew in the UK — hard vs soft tap water
- Roundleaf Sundew care — the full brief (light, soil, humidity, problems, pet safety)
- Watering calculator — get a starting interval for your exact pot and light
- Pot size calculator — the right pot keeps watering forgiving
- Overwatered plant — signs and how to recover it
- Underwatered plant — signs and how to rehydrate it
- Why is my plant wilting? Wet vs dry diagnosis
- How often to water peace lily
- How often to water bird of paradise
- How often to water hoya
- All 1284 watering schedules in the Growli library