Search
Indoor watering · Setup guide
GARDENA Holiday Watering: Reservoir Size and Siphon Checks
Some links in my articles are affiliate links. I may earn a commission when you buy through them.
For the GARDENA 1265/1266 holiday watering system, add the daily doses of every connected outlet, multiply by the number of daily watering cycles needed and provide extra usable water for variation. Keep the plants above the reservoir water level: GARDENA warns that a lower arrangement can continue delivering water after the pump stops.
A larger bucket does not make an untested layout dependable. First match the outlets to your plants, confirm that delivery stops correctly and check how much of the container the pump can actually use. This guide covers the mains-powered 1265/1266 system, not AquaBloom or a tap timer.
Count outlets and daily doses
The 1265/1266 manual describes three distributors, each with twelve outlets. Their daily quantities are 15 ml per light-grey outlet, 30 ml per medium-grey outlet and 60 ml per dark-grey outlet, during the system’s one-minute daily run.
A plant needing more water can receive more than one line, so the number of connected pots may be below the headline thirty-six. Record which outlet feeds each pot. For an established layout, labels prevent a helper reconnecting a low-dose line to a plant that had been using two higher-dose lines.
Close unused outlets as the manual directs. Use the supplied system components and follow the current product instructions for connections, power and installation. Altering the transformer’s timing with another timer is not a substitute for allocating suitable doses.
Calculate the water for your absence
Use this calculation after deciding which outlets will run:
Daily water in litres = total connected outlet doses in millilitres ÷ 1,000.
Base requirement = daily litres × planned watering cycles.
For an illustrative arrangement with four 15 ml outlets, four 30 ml outlets and two 60 ml outlets, the daily total is 60 + 120 + 120 = 300 ml, or 0.30 litres. Ten daily cycles require a base 3 litres. This is arithmetic using nominal manufacturer doses, not a measurement of a working installation or a recommendation for ten particular plants.
Count cycles rather than casually subtracting calendar dates. The manual says the first one-minute run begins when power is connected, with subsequent runs at the same time each day. Include that initial run if it draws from the water you are setting aside.
The calculated amount is a starting point. Confirm actual use during a trial, then allow additional usable capacity for variation and evaporation. There is no universal percentage that guarantees a safe absence in every room.
Choose a reservoir by usable capacity
The pump cannot use every drop at the bottom of a container. Check the required minimum water level in your supplied manual and identify the level below which the pickup will no longer operate properly. That remaining water belongs outside your usable-capacity calculation.
A nominal five-litre vessel is therefore not automatically a five-litre supply. Its stable fill line, the pump’s lower working level and any practical limit on keeping it safely positioned all matter. Measure the usable amount with a jug instead of estimating solely from the container’s shape.
Use a stable water container in a protected location and secure the pump and tubing as instructed. Leave access to refill without lifting a heavy full container over electrical equipment. Avoid a brim-full reservoir that spills when a tube is nudged.
Product 1266 historically included a nine-litre container; 1265 uses a separate reservoir. That packaging difference does not establish a nine-litre requirement for your plants, and it is not a claim that either kit is currently supplied in every market.
Prevent continued flow after the pump stops
The GARDENA manual identifies distributors below the reservoir water level as a cause of water continuing to flow after the pump has stopped. Follow its layout requirement to keep the plants above the water supply rather than putting the reservoir on a high shelf.
Check the highest water level you intend to use, not just the water left at the end of a trial. Raising a full bucket onto a stool can change the arrangement that previously worked. A refill must restore the tested level without moving the container or pots.
During commissioning, watch the tubes and pot trays after the one-minute run has ended. If delivery continues, disconnect power before changing the installation, protect the room from escaping water and correct the layout using the manual. Do not leave it operating while you hope the flow will stop.
A bigger catch tray provides some protection but does not correct a continued-flow fault. Find and resolve the cause before leaving the system unattended.
Trial plant response as well as water use
Start with normally watered plants and the final room layout. Note the daily reservoir fall, check every pot and inspect the trays. If a plant stays too wet, a calculated reservoir total does not justify continuing that allocation; choose a lower suitable dose or another care method.
Keep a simple record: pot identifier, outlet colour, number of lines, condition before the next daily run and any drainage. That gives you a basis for changing one allocation at a time. Measuring total reservoir loss alone cannot show whether one plant received too much while another dried out.
Repeat checks at the fuller and lower reservoir levels. Leave enough time before departure to correct a problem and observe the result. For a longer absence, arrange an inspection visit and leave the outlet record beside the kit.
Do not mix in plants whose care requires a different watering rhythm simply because spare outlets remain. Fixed daily dosing is a useful tool only when the chosen amounts and interval suit the plants being connected.
Power and purchase checks for UK buyers
Use only the supplied transformer arrangement specified for the kit, follow its electrical precautions and disconnect power before installation or maintenance. The manual calls for an RCD-protected supply and protection of the transformer from rain. Keep the supply dry and seek suitable qualified advice if you cannot provide the required arrangement.
The GARDENA 1265-20 listing on Amazon UK was checked as model 1265-20. We have not verified the supplied UK plug format. Before buying, ask the seller to confirm the exact complete kit and a suitable UK power arrangement. Do not assume a UK marketplace listing guarantees a UK plug, and do not improvise an electrical conversion.
If you already own a complete suitable kit, you may only need a stable reservoir and a better allocation plan. If suitable power or a low reservoir position is unavailable, consider a passive watering method or a helper instead.
Departure checks and further guidance
- Count every active outlet and the initial watering cycle.
- Confirm enough water remains above the lower working level for the whole absence, with additional capacity.
- Check all connections and that delivery stops after the daily run.
- Refill to the tested mark without changing reservoir or plant heights.
- Leave the pot-to-outlet record and refill instructions for the person checking the plants.
Our water-use calculation guide covers the wider method for turning delivery into storage requirements. The holiday watering checklist helps plan a final trial and helper handover.
Sources checked on 14 October 2026: GARDENA 1265-20 product information and the manufacturer’s 1265/1266 manual (2020 edition). Check the instructions supplied with your own model. This article contains no hands-on test results or promised unattended duration.