Hydroponic Garden Running Costs UK: The Real Numbers

The sum is short. Take the wattage of the LED, divide by 1,000 to get kilowatts, multiply by the hours it runs each day, then multiply by your unit rate:

Watts ÷ 1,000 × hours per day × unit rate = cost per day

Ofgem (the energy regulator for Great Britain) sets a price cap every three months. For 1 July to 30 September 2026 the capped electricity unit rate is 26.11p per kWh including VAT, and that is the rate used throughout this article. If you are on a fixed tariff, substitute your own rate - the shape of the answer does not change.

Nearly all of these gardens ship on a 16 hours on, 8 hours off cycle, which is what the figures below assume. If yours runs a 15-hour cycle, scale the results by 15/16 - about 6% less.

Click and Grow (an Estonian maker of pod-based countertop gardens) sits at the cheap end because its lights are small. The Smart Garden 3 is the least expensive thing here to run at almost exactly £1 a month, and it has no pump at all - it waters passively by wick, so the LED is the whole electricity bill.

At the other end, the largest 12-pod gardens cost about £3 to £4.50 a month. Even the worst case on this table, roughly £55 a year, is around 1% of the £1,862 a year the current cap assumes a typical household spends on gas and electricity combined.

iDOO (a budget hydroponic garden brand sold widely in the UK) is the one entry above with a range rather than a number, and the reason is worth understanding because it applies to other brands too.

The current official 12-pod product page lists 36 W, while earlier listings for the same ID-IG301 unit cite around 23 W. The clue is in the power supply: the adapter is rated 12 V / 3 A, which is 36 W. That is the ceiling for everything the unit can draw at once - LED, water pump and pollination fan together at full tilt - not what the light alone pulls for 16 hours a day.

So the 23 W end of that range is the more realistic figure for ongoing running cost, and the 36 W end is a worst case that assumes the garden runs flat out permanently. Whenever a spec sheet quotes a wattage that exactly matches the adapter rating, treat it as a maximum rather than a typical draw.

No. The circulation pumps in these gardens are small, and they do not run continuously - both the LetPot LPH-SE and the iDOO cycle theirs 30 minutes on, 30 minutes off, so a pump is only powered about 12 hours a day. The iDOO also idles its pump and fan for 10 hours overnight in quiet mode, cutting that further.

Manufacturers rarely publish pump wattage separately, so this one is an estimate rather than a specification: at a couple of watts running half the day, a pump adds in the region of £3 a year. It is a rounding error against the LED, and it is the reason a pumped hydroponic garden and a passive wick garden of the same light output cost about the same to run.

It does not, and this trips people up. The daily standing charge under the current cap is 57.19p, which works out at about £209 a year - far more than any garden on the table. But you pay it whether or not you own a hydroponic garden, so it is not a cost of running one.

Only the unit rate belongs in this calculation. Adding the standing charge would make a £20-a-year garden look like a £229-a-year one.

For most owners, the consumables - and it is usually not close.

The split is structural, and it is the single most useful thing to understand before buying. Click and Grow gardens use proprietary pre-seeded pods: the seed, the growing medium and the nutrients arrive as one sealed unit that only that manufacturer sells. Every replanting is a purchase from one supplier at whatever that supplier charges.

Open hydroponic gardens such as the LetPot LPH-SE and the iDOO work the other way. They take generic rockwool or sponge plugs, ordinary seed and standard A and B nutrient solutions, all of which are commodity items with many suppliers. That is why the gardens with the higher electricity cost on the table above are frequently the cheaper ones to own over a couple of years.

Prices for both move around too much to publish a figure that stays true, so the honest way to settle it for your own situation is to price one full replant of the garden you are considering, divide by the number of months a planting lasts you, and set that against the monthly electricity figure in the table. If a replant costs more than about £2 a month amortised, consumables are your dominant cost - which for pod systems they almost always are.