How to use a hydroponic herb garden
Updated: October 2026
The unit is already on the counter, and a blog’s single timetable does not match the buttons in front of you. How to use a hydroponic herb garden depends on whether you own a pumped tank or the DRYADES Z230 soil wick planter. This page covers water, feed, lamp hours, and cleaning for the listings in our [smart garden comparison](/hub/plant-accessories/smart-garden). It does not rank them. Doses below stay in the booklet that came in your box. If you are still choosing a pump kit or a soil pot, that split is a different page.
The unit is already on the counter, and a blog’s single timetable does not match the buttons in front of you.
The unit is already on the counter, and a blog’s single timetable does not match the buttons in front of you. How to use a hydroponic herb garden depends on whether you own a pumped tank or the DRYADES Z230 soil wick planter. This page covers water, feed, lamp hours, and cleaning for the listings in our smart garden comparison. It does not rank them. Doses below stay in the booklet that came in your box. If you are still choosing a pump kit or a soil pot, that split is a different page.
Our top picks
| Badge | Product | Routine | Lamp control | Feed in the box | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  REEPLAR REEPLAR 12-pod hydroponic garden | Pump tank | Programmable timer | Not in the attribute rows | 9.6 | about £59.99 | View offer |
| Best value |  DRYADES DRYADES Z230 soil planter, white | Soil wick | 8, 12 or 16 hours | None; you add compost | 8.8 | about £29.99 | View offer |
| Alternative |  LetPot LetPot LPH-SE 12-pod garden | Pump tank | App, 0 to 24 hours | A and B nutrients | 8.4 | about £99.99 | View offer |
On this page
Pump tank or wick pot
A pumped kit here is a tank, sponges or peat discs, a pump, and feed. You bring the seeds. The Z230 titles say no seeds and no soil. Click & Grow pods arrive pre-seeded and are not in this table.
The Z230 routine is compost in the pot and an absorbent rope. The lamp is 17 W, with 8, 12, or 16 hours. There is no A and B pair. Soil feed stays in the compost. Hydroponic nutrient stays in the pump tank. The Air prints both 3.5 litres and 4 litres. iDOO prints none. Follow the mark you can see. The pattern choice is on the hydroponic or soil page.
Feed, water, and air
Hydroponic nutrients are a mineral solution, not a pesticide and not compost for the Z230. Mix A and B as the bottle says, and keep the concentrates apart until diluted. Strong calcium stocks can drop out of solution if you combine them neat.
LetPot’s blog suggests 5 ml of A plus 5 ml of B per litre. That dose is not iDOO’s or DRYADES’. The RHS says discard a recirculating solution about every two weeks, because topping up can leave it too strong. If you follow the ID-IG301 manual, skip softened water. If the pump is silent for days, empty the tank.
Hours the lamp is actually built for
The RHS example is about 16 hours, not all night. The Z230 offers 8, 12, or 16. The DRYADES 8-pod bullet says 16 on and 8 off. One review could not hold that cycle, so check the next evening.
Normodic presets are 12, 14, or 16. LetPot app rows claim 0 to 24. iDOO can rest the pump for 10 hours, then alternate 30 minutes. Set that once. Hocomay prints no hours, so read the buttons. At 26.32 pence per kWh, 24 W for 16 hours is about 10 pence a day before the pump.
Cleaning and when to stop
Algae or a sour smell means empty the tank, wipe it, and mix a fresh batch. Two weeks is the RHS interval for recirculating solution. Sooner if the pump has been off. Take germination domes off once leaves show. One DRYADES review mentions fungus gnats, which like a wet sponge or a damp compost surface.
A dead pump turns the kit into a lamp over still water. If no replacement pump exists, the unit has finished its job. Plan a second bottle of A and B while the first is half full. Keep the adapter above the tank. If the plug is hot, or the RCD trips, unplug it and call an electrician. A flickering lamp is a reason to stop, not a reason to fit a travel adapter.
Common questions
Do I put soil fertiliser in the tank?
No. Soil fertiliser, compost tea, and tomato feed are mixed for compost. A pump tank wants the nutrient that listing named, diluted into the water. The Z230 takes compost in the pot, not A and B poured into the base.
Can I pour A and B together before I dilute them?
No. Pour each into the tank water, and keep the concentrates apart. Strong stocks can throw calcium out of solution if they meet while still neat. LetPot’s 5 ml plus 5 ml per litre is that brand’s blog. Normodic’s solid fertiliser follows its own label.
How long should the lamp stay on?
Use the hours your listing offers: 8, 12, or 16 on the Z230, 16 on and 8 off on the DRYADES 8-pod, 12, 14, or 16 on Normodic, and 0 to 24 on a LetPot app row. The RHS example is about 16 hours, not all night. Hocomay prints no hours, so use the buttons on the machine.
How often should I empty the tank?
About every two weeks for a recirculating solution, which is the RHS interval, because topping up can leave the feed too strong. Sooner if the pump has stopped, the water smells, or algae coats the wall. LetPot’s blog is looser. The Z230 base is a top-up you can see, not a place for hydroponic concentrate.
What if the listing is a soil wick, not a pump?
Fill the pot with compost, sow your own seed, and let the rope bring water up. Set 8, 12, or 16 hours. The white Z230 prints 0.7 litres. The black listing does not, so fill to the mark you can see. If basil outgrows 14 × 16 × 15 cm, move it on.
The sponges had no seeds. Is that a fault?
On these listings, missing seeds are the normal parts list. LetPot’s warm tip on the Air says the sponges do not include seeds. iDOO’s bullets do not name seeds, and one reviewer said the box had none. The Z230 title says no seeds and no soil. Buy seed for the herb you actually want. Pre-seeded pods belong to closed-pod gardens such as Click & Grow, which are outside this table.
What do I do if the plug is hot or the RCD trips?
Unplug it and leave it unplugged. Call an electrician. Do not swap in a travel adapter and carry on, and do not stand the power supply where tank water can reach it. The same stop applies if a lamp that failed weeks ago is being asked to run through a hot plug. Plants can wait. A hot plug should not.
Related pages
Sources
Public UK sources used for this comparison. Shelf prices, stars and review counts are the amazon.co.uk figures captured for these ten listings. Last checked 22 October 2026.
- RHS hydroponics (retrieved 22 October 2026)
- RHS artificial lighting (retrieved 22 October 2026)
- Electrical Safety First, plugs and fuses (retrieved 22 October 2026)
- Electrical Equipment (Safety) Regulations 2016, regulation 35 (retrieved 22 October 2026)
- Ofgem price cap, 1 October to 31 December 2026 (retrieved 22 October 2026)
- Click & Grow UK, Smart Garden 9 PRO (retrieved 22 October 2026)
- MetroFarms, best smart garden under £200 (retrieved 22 October 2026)
- amazon.co.uk listings for the ten ASINs, plus Click & Grow B0778YCS5T (retrieved 22 October 2026)