Greenhouse watering systems: can, hose, drip or capillary matting?
Every greenhouse plant is watered by you, because no rain reaches it. That is the whole job of a watering system: to deliver water to the roots steadily, without wetting the leaves, on the days you are busy or away. Start with what you grow, in beds or pots, and how often you can be there; a can and a water butt cover a small house, and drip lines or capillary matting take over as it fills up.
- Water the roots, not the leaves. The RHS asks for water at the root zone; wet foliage under glass invites mildew.
- Beds and pots differ. Pots dry out faster and may need water daily in hot spells; beds can go longer between thorough waterings.
- Automate the routine, keep checking. Drip lines and capillary matting save time, but someone still needs to look at the compost.
Which greenhouse watering system suits you?
A watering can and a water butt for a small greenhouse you visit daily. Drip lines or a seep hose for beds, capillary matting for pots on staging, and a timer if you can’t be there every day.
| Method | Best for | Watch for | What you need |
|---|---|---|---|
| Watering can | Precise watering of pots and young plants | Time and carrying | A can with a rose, ideally filled from a water butt |
| Hose | Larger greenhouses where a can is impractical | Wetting the leaves; use the hose at the base of the plants | A hose with a gun or lance |
| Drip line | Beds and grow bags, with an emitter at each plant | Blocked emitters; check each plant still gets water | Tubing, emitters, a tap or pump, often a timer |
| Seep hose | Beds, watering along their whole length | Uneven flow on long or sloping runs | A porous hose laid along the bed |
| Capillary matting | Pots on staging | Small reservoirs running dry; good contact between pot and mat | Matting, a reservoir, a flat staging surface |
| Water butt | Storing rainwater for any of the above | Capacity in a dry spell | A butt and a downpipe or diverter |
The RHS recommends a watering can wherever possible, for precise and sustainable watering, and a hose when the size of the area makes a can impractical. Sprinklers, it says, are acceptable only in very limited circumstances, and under glass they also wet the leaves.
How should you water a greenhouse?
Thoroughly and at the base. Water less often but more deeply in beds, check pots every day in warm weather, and water in the morning so leaves stay dry.
The RHS watering guide puts it simply: water less often but more thoroughly, and aim at the root zone rather than the leaves or the soil around. Plants in containers dry out faster than in the ground and need checking regularly; in a dry spell they may need water every day. For greenhouse cucumbers, the RHS adds watering at cooler times of day, ideally the morning.
Steady watering is also the best defence against several crop problems. The RHS links blossom end rot and splitting in tomatoes to moisture that comes and goes, which our tomato guide covers in detail.
Is drip irrigation worth it in a greenhouse?
For beds and grow bags, often yes: drip lines put water at each plant and seep hoses along the bed, with a timer if you need one. Check them, because blocked emitters and empty butts stop the water quietly.
Drip lines are tubing with emitters spaced along them; seep hoses release water along their whole length, the RHS explains. Many systems run on a timer, and some take a rain sensor. Lay the line along the bed close to the stems, and set the timer for early in the day. Then keep checking: a blocked emitter can leave one plant dry while its neighbours thrive.
A mains-fed kit, as University of Maryland Extension sets it out, starts at the tap with a filter that has a removable strainer, followed by a pressure regulator. Drip from a water butt needs either a pump or enough height for gravity to push water through the emitters, so ask the kit’s maker which supply it is designed for before you buy.
How do you water pots on greenhouse staging?
By hand, or on capillary matting fed from a reservoir. The RHS describes the method for pots indoors, and the principle on staging is the same.
The RHS holiday care advice drapes one end of the matting into a reservoir of water and groups the pots on the wet mat, pressed down slightly so they make good contact. Clay pots need a thorough watering first to start drawing water from the mat, and the method may not work with pots that have broken crocks in the bottom. For a single large pot, a strip of matting can act as a wick from a container of water. Small reservoirs dry up and wicks slip out, the RHS warns, so check both.
Should you water a greenhouse with rainwater?
Where you can, for established plants. The RHS advises collecting rainwater in water butts and using mains water only as a last resort, but keeping stored water off seedlings.
A water butt by the greenhouse saves carrying water from the house and fills the can at the door. Store rainwater from hard surfaces such as a roof, the RHS says, and its guide to storing water adds the details: a firm, level stand high enough for a can under the tap, a close-fitting lid, a filter to keep leaves out, a pump if you want pressure for a hose, and a wash-out once a year. Use stored rainwater on established plants, not seedlings, because it can carry damping-off diseases. In a long dry spell a butt runs out, so keep the mains as the back-up rather than the plan.
How do you water a greenhouse while you’re on holiday?
With a system you have tested before you go: drip on a timer for beds, capillary matting for pots, and a neighbour who checks both.
- Run the whole system with every outlet connected, for a week while you are at home.
- Check each pot, bed line and mat for a dry outlet, a leak or water running onto the path.
- Feel the compost after each run and move outlets or change the timer to suit.
- Watch how fast the butt or reservoir falls, and plan the refilling around it.
- Show your helper the shut-off, the timer and the plants that need separate attention.
Our guide to watering a greenhouse while you’re away goes through the options, and keeping a greenhouse cool cuts how much water the plants need in a heatwave.
Quick answers about greenhouse watering
It depends on the plants and the weather. Check pots daily in warm weather, as they may need water every day; beds do better with less frequent, thorough watering.
The RHS suggests cooler times of day, ideally the morning, for greenhouse cucumbers, so the leaves dry quickly.
The RHS considers sprinklers acceptable only in very limited circumstances, and under glass they wet the leaves, which encourages mildew. Water at the base instead.
No. Our greenhouses come ready for a can, a hose or your own irrigation kit; staging and watering are arranged separately.
What should your watering set-up cover?
Water at the roots, a source close by, a way to cope with hot days and a plan for when you are away.
Six things to settle
Tick them off before the season starts. Your ticks stay on this device.
Beds either side of the path
Both take a bed down each side of a central path, ready for a can, a hose or your own drip line.
- Width
- 2.6 m walk-in
- Lengths
- 2 to 6 m, 8 × 6 to 8 × 20 ft
- Ridge
- 2.3 m, eaves 1.51 m
- Frame
- 45 × 45 mm FSC pine, galvanised brackets
- Glazing
- 4 mm twin-wall, 6 mm option
- Air
- opening door top and rear window
- Width
- 3.00 m on the ground, 3.14 m at the widest
- Lengths
- 4, 6, 8, 10 or 12 m
- Ridge
- 2.02 m
- Glazing
- 4 mm twin-wall, 6 mm option
- Air
- two gable doors, upper halves open
- Roof vents
- optional, automatic openers
From the product pages, 20 October 2026. Staging, watering and the base are arranged separately.
See the layout before you plan the watering
The NORDIC page shows the beds and path for every size. An expert can help you plan the space.
What we checked for this guide
Watering methods and advice link to the RHS pages they come from. We don’t sell watering systems. Checked 20 October 2026.
- 01RHSGarden watering methods
- 02RHSHoliday care: capillary matting and wicks
- 03RHSWatering vegetables and fruit
- 04University of Maryland ExtensionDrip irrigation
- 05RHSCollecting, storing and using water
Related guides
Written by the Waldenhaus team. We sell outdoor saunas and greenhouses and write these guides from manufacturer manuals, official guidance and our own product pages. Where your equipment manual says something different, follow the manual.