WaterMate Solar Core Irrigation System Features

Spend less time watering, and more time enjoying your garden.

Build your own WaterMate system from scratch! The WaterMate Solar Core is our solar powered do-it-yourself irrigation option. Choose your own pump, fixings, and outlets for a fully customised greenhouse or polytunnel irrigation system. Our system is compatible with other industry standard sized components, so you can still utilise your favourites or explore our options.

The Harvst WaterMate allows you to water across two zones for precise control, reduced water consumption and healthier plants. The WaterMate is designed for watering:

  • Greenhouses
  • Polytunnels
  • Garden beds
  • Allotments
  • Plant pots (including hanging pots, no more water down your sleeves!)

Set timers to deliver regular and specific amounts of water when you want and for complete peace of mind program the temperature sensor to automatically trigger extra watering when it gets too hot. And, never need to replace a tap timer battery again with the power of solar.

WiFi enabled (will run without internet too) so you can remotely control and monitor your system and even receive email alerts for high/low temperature, when watering, or if your tank is empty*. 

WaterMate is designed and built by Harvst, in the UK. 

*Must be connected to home WiFi for alerts.

Why choose solar power?

If you don’t have mains electricity in your greenhouse or polytunnel, you can still have powerful automatic watering. The battery is charged by a small solar panel which should be mounted outside to catch the most sun.

Up to 10 minutes of watering time is possible per day in the summer (5 minutes most at one time) and can deliver up to 120L of water.

Supplied with 3m of cable, extensions available.

Thinking about mains power?

If you have 240V power, we recommend you use the mains version. You will be able to water for longer periods and won’t be limited by darker days in winter. The WaterMate 4-Season Core is available for those who want flexibility of our core models with mains power.

 You will be able to add more pumps / misters or even our LED grow lights, heated seed trays (coming soon) for propagation, or heater cables.

The power supply comes with 5m of mains flex.

Self watering, so you don't have to.

Your Harvst automatic watering system takes care of the watering while you are away, and also provides a regular watering regime which helps many plants grow better.

WaterMate with pump mounted to a garden bed.

Why choose pump watering?

You can water your greenhouse or polytunnel automatically even if it’s nowhere near a tap; all you need is a water tank nearby. The powerful Pro pump will deliver up to 17 litres/min at 35psi (more than mains water pressure). For smaller greenhouses, you can use the Mini pump. Choose the pump model for a pressurised, high flow rate off-grid system which can run from a water butt or tank.

Why choose hose watering?

If you have a water tap in or near your greenhouse or polytunnel, you can connect it directly to the dual zone water valve and leave the pump out. If you have mains pressure water at your greenhouse, choose the garden hose mode.

Dual zone watering helps maximise your garden’s productivity.

WaterMate supports two independent watering zones, using an electric water valve. Each can be controlled using a completely different program, and different sensor inputs. Or, use the two zones to cover a larger area with the one pump.

You could set one zone up for misting/spraying (great for seedlings or salads) and the other zone for drippers (great for plants like tomatoes).

Versatile, flexible, powerful.

Peace of mind, productive growing, and less time spent watering.

Regular irrigation with consistent amounts of water has several benefits compared to relying solely on rain or hand watering. Here are some advantages of regular irrigation:

  • Precision and Control:
    Consistent irrigation allows you to control the amount of water your plants receive, ensuring they get the right amount to thrive. This control is essential for different plant types and growth stages.
  • Water Efficiency:
    WaterMate is designed to be used with a variety of fitting including drippers to minimise water wastage by targeting the root zone of plants directly. This reduces the risk of overwatering or underwatering, which is common with hand watering.
  • Plant Health:
    Regular and consistent irrigation helps maintain consistent soil moisture levels, which is crucial for plant health. It minimises stress on plants and reduces the risk of drought-related damage.
  • Time Savings:
    WaterMate saves you time compared to hand watering. You don’t need to be present for every watering session.
Sprayer installed in a greenhouse.
  • Disease Prevention:
    Watering at ground level with irrigation systems helps keep foliage dry, reducing the risk of fungal diseases that thrive in wet conditions, such as powdery mildew or leaf spot.
  • Convenience:
    Regular irrigation can be set on a schedule, ensuring that your plants receive water even if you’re away from home or have a busy schedule. This is not as convenient with hand watering or relying on rain.
  • Improved Root Development:
    Consistent irrigation encourages plants to develop deeper root systems, as they are less likely to be stressed by fluctuating soil moisture levels.
  • Yield and Growth:
    For agricultural or garden crops, regular irrigation can lead to higher yields and faster growth because the plants have a stable and reliable water source.
  • Adaptation to Specific Plant Needs:
    Different plants have different water requirements. With irrigation, you can tailor the watering schedule to the specific needs of each plant variety in your garden or landscape.

Manage and monitor from anywhere with the Harvst app.

Settings are managed directly on the system using any phone, tablet, or laptop. No app needed, no registration required. We do however have a companion app, which brings the following handy benefits:

– Alerts when you need to fill your water tank (pumped version)

– Waters more when it’s hot and sunny, and less when it’s cool and overcast: healthier plants, and saves you water.

– Data logging of growing conditions in the system

– Remotely monitor watering and temperature

automated mini greenhouses uk

Join a Community

On top of all the automation capabilities of our web app, you can join a community of gardeners! Get expert tips, advice, and troubleshooting direct from us and other users.

The app provides a grow diary in which you can record and share when you sowed, when seeds germinated, etc. and upload photos. You can also set reminders for when to do things like sow more seeds.


Control Box Measures 19cm (W) x 12cm (L) x 4.5cm (D) • 10W Solar Panel Measures 35cm (W) x 22cm (H) x 1.8cm (D) • Dual zone 12V electric solenoid water valves with twin 12mm barbed outputs  Built in 14.8v 2900mAh lithium ion battery

What's in the box?

Construction & Power

WaterMate control system for automation and monitoring with WiFi connectivity.

Solar panel power supply provided.

Made in Britain logo


– Dual zone water valves

– Solar panel brackets


– Air temperature sensor

– Web app for Android and iPhone

Compatible with (not included)

Installing into a greenhouse (not included)

Greenhouse fixings fix pipes to the aluminium frame of a greenhouse.

Control unit mounting plate

Installing into a polytunnel (not included)

Polytunnel fixings for straining / support wire to run down each side of the polytunnel, to which you attach your distribution pipe.

  • 30m galvanised wire
  • 2 wire tensioners
  • cable ties
Polytunnel irrigation kit
Polytunnel mounting kit

A typical installation is shown in the drawing (with options for inline and submersible pumps both shown).

Two separate runs of 13mm LDPE distribution pipe are run around your greenhouse or polytunnel, into which you can fix sprayers / misters directly, or add 4mm dripper lines.

You can also connect a garden hose directly to the water valves instead of using a pump.


By empowering you to grow your own fruits, vegetables, and herbs at home, WaterMate significantly reduces the environmental footprint associated with traditional food supply chains.

Reducing Packaging and Food Miles

When you cultivate your own garden, you directly contribute to lessening the demand for packaged goods. Growing your own food means fewer trips to the supermarket, translating to fewer food miles for the produce you consume at home. This reduction in transportation emissions helps lower your carbon footprint.

Minimising Food Waste

Harvesting only what you need, when you need it, leads to fresher produce and less waste. The ability to control your crop yield with WaterMate ensures that you are not buying in bulk and then throwing away spoiled food.

Eco-Friendly Packaging

Our commitment to sustainability extends to our packaging. WaterMate’s packaging is crafted from recycled and recyclable materials, ensuring that even our product’s delivery has a minimal environmental impact.

Sustainable Materials

The WaterMate system itself is constructed using durable, sustainable materials. We utilise recycled components wherever possible and ensure that all parts of our system are built to last multiple seasons.

Harnessing Solar Energy

Embracing renewable energy, some models of the WaterMate come equipped with a 10W solar panel. This allows the system to operate efficiently using solar power, reducing reliance on traditional electricity sources and lowering energy bills. Solar energy is a clean, renewable source that reduces greenhouse gas emissions and supports a sustainable lifestyle, making your gardening practices even more eco-conscious.

Additional customisation options for your garden.

Water precisely when your plants need it most (even when you're on holiday).

Our WaterMate systems include a temperature sensor out of the box but if you want more control over your greenhouse’s environment, we also have a wireless humidity/temperature sensor you can add to your set up!

Designed for easy installation.

We’ve worked hard to make the WaterMate range easy to install into your greenhouse. We supply tools, including M6 cropped head bolts and P-clips to fix pipes and parts to a greenhouse frame, a genuine English setup manual, as well as videos to help you along the way.

Visit our getting started pages, or browse our community support forums.

For help setting up your control box, check out this Youtube playlist. We have videos for both online and offline use. For examples of how other users have set up their drippers, sprayers, foggers, and other outputs, we have a playlist for that, too!

Feel free to reach out to us at support@harvst.co.uk or via our forum if you have any further questions. We’re always happy to help!


Do I need to have WiFi to use the WaterMate?

No! WaterMate will run fine without WiFi. The system will transmit its own WiFi signal, which you can connect to when you are within a few metres of the control unit.

How do the alerts work?

If you have a WiFi network within range of your greenhouse, the control system can connect to it, and will send data to the Harvst servers every half hour. If you’ve set your account up to receive email notifications, you can stay in touch wherever you are.

Do I need a smart phone to use the WaterMate?

During the initial set up and to change settings, yes. However, to simply turn the system on or off, you can do that via the control panel manually.

Why can’t I find the app on iTunes or Google Play?

The Harvst control app is a ‘web app’ which means it operates directly through an internet browser such as Safari, Chrome or Firefox. This lets you use any device, from anywhere.

Is WaterMate a greenhouse drip irrigation system?

Yes, in that you can fit micro irrigation drippers to the hoses, but it is not gravity fed. It’s a high pressure system which helps prevent the nozzles clogging – a common problem with low pressure or gravity fed drip watering systems.  The benefits of drip irrigation include the ability to deliver water only to the roots of a plant – great for watering those that don’t like wet leaves, and helps you save water.

How do I control greenhouse or polytunnel humidity with WaterMate?

A combined temperature and humidity sensor is available as an optional extra. You can use the humidity reading (or temperature reading) to turn on the auxiliary output; into which you connect the Harvst pro pump and mister system.

How do I setup my watering regime?

You will need to log on to the Harvst web app, using a smartphone. From there, you have access to the following settings for two zones:

  • How long to water for; water for as long or short as needed (we recommend no longer than 10 minutes)
  • When to water; from twice a day to once every 5 days
  • Solar boost; when it’s been hot and sunny for more than 4/6/8 hours, to give extra water

Watering is automatically reduced on cloudy, overcast days.

How long do I need to water for?

Each zone can be set to water from 1 second to 5 minutes at a time (any time can be set through our settings, we do not recommend more than 10 minutes). Five minutes might not sound like much, but with water being delivered to the whole area at once, this is a significant amount of water. The pump is rated at 12 litres per minute, which reduces to approximately 10 litres per minute when you have the valves, nozzles, drippers etc connected. Five minutes would be 50 litres.

How do I install the irrigation pipework?

Everyone’s use of our WaterMate is different, so there is no ‘correct’ way to set up your irrigation pipes. We recommend that you have the two watering zones set up with distribution pipes around the perimeter of your greenhouse, polytunnel, or garden beds – with either sprayers inserted directly into the pipe, or with take-offs at regular intervals for rings of drippers on a 4mm hose.

You would use drippers for larger plants where you know exactly where the water is needed, and use sprayers for larger areas of plants (such as salads), or for seedlings.

How long can the pipes be?

The WaterMate Pro pumps can provide water for many tens of metres of pipe, and up to 5m of vertical head. If you add too many drippers and water outlets to the line, the flow rate per outlet will drop. Too long a pipe and your first outlets will start working a long time before your last ones, leading to overwatered plants at the start and under watered plants at the end. Try to set up your irrigation system in a ring.

We provide 6m of inlet hose (between the water tank and the pump) but the system will run with at least 10m of inlet hose and a 4m vertical head. The pump is self priming.

What irrigation parts are compatible with WaterMate?

We’ve designed the system to work with any off-the-shelf irrigation and micro-irrigation parts. The kits are provided with 13mm LDPE pipe, 4mm micro irrigation kits, and a selection of spray nozzles for you to experiment with. When you have decided what you like, you can add more.

Can I use a soak/porous hose?

Yes, you can. The WaterMate Pro pump is capable of powering at least 15m of hose. It will cycle on/off once the hose has reached pressure.

Can I use misters or foggers?

Yes, you can. The WaterMate Pro pump is capable of powering at least 20 mister outlets per zone.

Can I override the automatic watering manually?

Yes. If you’re in the greenhouse or polytunnel, you can either use your smartphone or you can use the button on the control unit if you don’t have your phone with you.

Can I manage the watering system while I am away on holiday?

Yes, if your greenhouse or polytunnel is within range of a WiFi network. The control unit connects to the internet every 30 minutes to send a data update, and collects any changes to settings you have made.

Can I run heaters and lighting with WaterMate?

If you choose a mains powered WaterMate 4-Season Core, yes. Solar powered WaterMates cannot directly run heaters or lights. If you would like a solar powered WaterMate but would also like to add Harvst soil warming cables, heated trays (coming soon), or LED grow lights, the core pack is available in a mains powered version (UK 240V) can be added to support these accessories.

Is the pump noisy?

It’s remarkably quiet for such a powerful pump. It’s mounted on rubber feet, and if you place it in a suitable location you probably won’t hear it running at all!

Can I use a tap instead of the pump?

Yes! WaterMate will work fine with a tap, so you won’t need a pump. Select the garden hose choice when you order. The hose (which must be left turned on) simply connects to the dual watering zone valves which act as an electric tap.

How & where do I mount the solar panel?

We provide a versatile solar panel mounting bracket, which is screwed to a wall or post. You can place the solar panel in the optimum position for sunshine (outside the polytunnel or greenhouse is best) up to 3m away from the control unit. Solar panel extension cables are available.

I have mains power in my greenhouse or polytunnel, can I use that?

Yes, you can. We provide an alternative control unit which does not need the solar panel. We also have a Mains 4-Season core unit, which comes with extra outputs for additional pumps, heater cables and/or grow lights.

What about air locks? Is it reliable?

The powerful self priming pump does not suffer from air locks, so if your water tank runs out and then refills later, the system will have no problems restarting, without you needing to prime it.

What about frost damage and decommissioning it for winter?

WaterMate has automatic frost damage protection. It will not run the pump if the temperature falls below 1 degree centigrade. Here is a guide to decommissioning your WaterMate for winter.

Are replacement parts available? Is there a warranty?

Yes, all components are available as replacements or upgrades. There is a 2 year manufacturers warranty on all major components. Warranty on batteries in solar units is 1 year from purchase.