When less isn't more
There's been a lot of (justified) emphasis on not overwatering houseplants, but underwatering is a real problem too. The worry about overwatering can make people overly cautious, especially with non-succulent plants that genuinely do need regular water. Prayer plants, boston ferns, maidenhair ferns, and peace lilies will wilt rapidly if they dry out too much, and repeated severe drying damages the roots over time.
In the UK, underwatering tends to be more of a summer problem when warm temperatures dry compost out fast, and when plants are actively growing and using more water than usual. But it can also catch people out in spring when they've been cautious all winter and forget to increase watering as temperatures rise and day length increases. A plant that needed water every 10 days in January might need it every 5-6 days by May.
Knowing the signs of underwatering — and telling them apart from overwatering, which can look similar — is essential for keeping plants healthy. This guide covers what to look for and how to rehydrate a seriously dry plant properly.
How to identify underwatering
- Compost is dry and pulling away from the sides of the pot
- Pot feels very light when you lift it
- Leaves are wilting or drooping — but the compost is dry
- Leaves feel dry, thin, and papery rather than soft and plump
- Leaf edges or tips are crispy and brown
- Lower leaves are dropping off
- Slow or no new growth despite being in the growing season
- Soil is repelling water — it runs straight off rather than soaking in
The key distinction from overwatering: stick your finger into the compost. With underwatering, it's dry. With overwatering, it's wet. Always check the soil before deciding what to do.
Common causes
Watering too infrequently in summer
Plants grow fastest between April and September in the UK, and they use correspondingly more water. A watering schedule that worked through winter won't cut it in summer, especially if the plant is in a warm sunny spot. Smaller pots and terracotta containers dry out particularly fast — a terracotta pot in a sunny south-facing windowsill might need watering every 2-3 days in July. Check compost moisture frequently in the warmer months rather than assuming the schedule is still right.
Being too cautious after overwatering advice
It's very common to overcompensate. Someone reads about overwatering, gets anxious, and drastically cuts back on watering — sometimes too much. This is especially a problem for plants that genuinely do need consistent moisture, like ferns, prayer plants, and peace lilies. The goal isn't to keep the compost bone dry, it's to keep it evenly moist without being waterlogged. There's a wide middle ground.
Small or clay pots in warm rooms
Terracotta pots are porous and lose moisture through the pot walls as well as through the top. This makes them great for plants that like to dry out, but tricky for thirsty plants. Small pots in warm rooms can go from damp to completely dry within a couple of days. If your plant is consistently drying out too fast, either water more frequently, move to a slightly larger pot, or switch to a plastic or glazed ceramic pot that retains moisture better.
Rootbound plants
When a plant's roots have completely filled the pot, there's very little compost left to hold moisture. Water runs through almost immediately and the roots are left dry. If your compost dries out very quickly despite regular watering, check whether the plant is pot-bound — roots circling the bottom of the pot or emerging from drainage holes are the signs. Time to repot.
Hydrophobic compost
Compost that's been allowed to dry out completely can become hydrophobic — it repels water rather than absorbing it. You'll notice water pooling on the surface and then running around the edges of the pot and straight out of the drainage holes, having barely touched the dry central rootball. This is especially common with peat-based composts. The fix is bottom-watering (see below).
How to fix it
- Check the compost first. Make sure it really is dry before doing anything else.
- Water thoroughly from the top. Water until it runs freely from the drainage holes. Don't just add a splash — give it a proper soak.
- Bottom-water if the compost is hydrophobic. Place the pot in a bowl or sink with a few centimetres of water and let it soak for 20-30 minutes. The compost will draw water up from below and re-wet evenly. Drain properly afterwards.
- Don't try to compensate by over-watering. Once you've given a thorough drink, let the plant recover and only water again when it needs it.
- Check for root damage. Severe repeated underwatering damages roots. If the plant is severely wilted and doesn't perk up within a day or two of watering, the roots may need time to recover. Keep in a slightly more humid spot and be consistent with watering going forward.
Prevention
- Check compost moisture regularly rather than watering to a schedule — needs change with the seasons.
- Water more frequently in summer, especially for plants in terracotta pots or small containers.
- Bottom-water occasionally to ensure the whole rootball gets evenly moist.
- Repot rootbound plants so there's enough compost to hold moisture.
- Consider moving thirsty plants like ferns to plastic or glazed pots in summer.
Which plants are most affected?
- Prayer plant — wilts quickly and dramatically when dry
- Boston fern — fronds go brown and crispy rapidly when underwatered
- Maidenhair fern — extremely sensitive to drying out, can die back completely
- Peace lily — wilts dramatically but usually recovers quickly once watered
- Pothos — leaves wilt and may go yellow when consistently underwatered
Frequently asked questions
My peace lily wilted dramatically — will it recover?
Very likely yes. Peace lilies are dramatic wilters but they're also resilient. Water thoroughly and most will perk up within a few hours. If it's wilted very badly and been dry for a long time, give it a bottom-water soak and move it somewhere slightly more humid. Avoid watering again until the compost surface starts to dry slightly.
How do I know when my plant needs water without testing the soil every day?
Lift the pot. A dry pot is noticeably lighter than a wet one, and once you get used to the difference it becomes intuitive. You can also learn the visual cues for each specific plant — pothos leaves start to look slightly less glossy before they wilt, for example. Over time you develop a feel for each plant's rhythm. But when in doubt, test the compost.
Is it possible to water too much when trying to fix underwatering?
Yes. Give one thorough watering and then wait. Don't water again the next day to make sure. Roots that have been drought-stressed are in a fragile state and need to recover in evenly moist compost, not waterlogged compost.
The water is running straight through the pot — why?
Hydrophobic compost. The dry compost is repelling water and it's flowing around the edges rather than soaking in. Try bottom-watering by sitting the pot in a bowl of water for 20-30 minutes, or water very slowly in small amounts and let each amount absorb before adding more.
My plant looks wilted even though I watered it yesterday. What's going on?
If the compost is wet and the plant is still wilting, this is almost certainly overwatering or root damage rather than underwatering. Wet roots can't function and the plant wilts as a result. Check our overwatering guide and root rot guide for next steps.
Should I mist my plant if it's underwatered?
Misting the leaves doesn't address root-level drought — it only briefly raises humidity around the leaves. It won't rehydrate a dry plant. You need to water the compost. Misting on top of watering is fine for humidity-loving plants, but it's not a substitute.