How to set up a grow tent
Updated: October 2026
The tent or the dome is on the floor, and you want seedlings alive rather than a melted lid or a sagging pole. This is how to set up a grow tent in a UK room, and when a humidity dome is the other path. Listings refer to our [grow shop comparison](/hub/plant-accessories/grow-shop), captured on 19 October 2026. A qualifying purchase can earn us a commission at no extra cost to you. Opened a tent, start there. Bought a dome, use that section, then still dry-run before you sow. Lawful crops only. A tent does not license cannabis cultivation.
The tent or the dome is on the floor, and you want seedlings alive rather than a melted lid or a sagging pole. This is how to set up a grow tent in a UK room, and when a humidity dome is the other path.
The tent or the dome is on the floor, and you want seedlings alive rather than a melted lid or a sagging pole. This is how to set up a grow tent in a UK room, and when a humidity dome is the other path. Listings refer to our grow shop comparison, captured on 19 October 2026. A qualifying purchase can earn us a commission at no extra cost to you. Opened a tent, start there. Bought a dome, use that section, then still dry-run before you sow. Lawful crops only. A tent does not license cannabis cultivation.
Our top picks
| Badge | Product | Assembly | Hanging load | Watch for | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  AC Infinity AC Infinity CLOUDLAB 844 4×4 tent | UK reviews often call it easy | 150 lb stated, about 68 kg | Seam leaks, tent only | 8.9 | about £239.00 | View offer |
| Alternative |  AC Infinity AC Infinity humidity dome kit 5x8 | Bench kit, several cables | Not a hanging tent | Mat melted a dome in one UK review | 8.1 | about £90.99 | View offer |
| Alternative |  Secret Jardin Secret Jardin Hydro Shoot 120 cm tent | Canvas wants a second person | Not printed on the listing | 120 × 120 × 200 cm, no lamp | 6.4 | about £85.99 | View offer |
On this page
Tent first, in the room it will live in
Assemble the tent where it will stay. GroWell says to build the frame, then the canvas, in the final spot, not on a carpet you will drag, and not to force a twisted zip. Greens Horticulture says the same, with about 20–30 cm of clearance for ports. A 200 cm tent plus a roof duct needs more ceiling than the printed canvas height. Put it by a socket you can reach without a chain of adaptors, and decide the duct exit before you hang anything.
A catch tray wants a level floor. CLOUDLAB 844 reviews often call assembly easy. A German Hydro Shoot review says the instructions are clear, but the canvas is hard to pull over a 120 cm frame alone. Budget a second person. This page assumes the tent is already yours.
Hang air, then light
Hang the filter and extractor high before the lamp. One Stop Grow Shop says the fan arrow should point away from the filter, so air is pulled through the carbon and pushed outside, on a short duct. Use rated bars, not a stitched corner. The CLOUDLAB 844 states a 150 lb maximum, about 68 kg. Greens’ Hydro Shoot roof note is up to 30 kg, and the amazon listing prints no load. Near 30 kg, the cheaper tent is the wrong experiment.
Hang the light on ratchets, keep a low intake open, add a small fan over the leaves, then set a timer. Follow the lamp’s own range. For the SANSI clamp, UK reviews say keep the heads about 10 cm off the foliage.
If you started with a humidity dome
The RHS line on indoor sowing is easy to miss: take the cover off as soon as shoots appear, and keep trays clean. A sealed dome after germination is how seedlings damp off. Open the vents as soon as you see green, and lift the lid.
The AC Infinity kit includes a heat mat. One United Kingdom review says that mat melted the plastic dome on the lowest setting, and other reviews say the control is a dial, not an exact thermostat. Keep any controller dry, outside the wet tray, and do not sandwich the mat against the lid.
A 24-hour dry run before you sow
Run a day with no plants. Look for light at the zippers with the room dark and the lamp on. The 844 is praised for thick fabric and also has a UK pin-cushion seam report, so look. If a plug is hot, or you smell softening plastic, switch off. The Mars Hydro pump in this set is called extremely loud, and its bullets list 110 V, so do not learn that on a UK socket.
Sow only after that. If you need a new circuit, the room is growing mould, or the crop is a controlled plant, stop.
The first night, in order
If the box is a tent, build it where it will stand, hang the filter and fan on rated bars, then the light on ratchets, and leave a low intake open. If the box is a dome, open the vents as soon as you see green and do not leave the heat mat against the lid. In either case, run a day with no plants and stop if a plug is hot or plastic smells soft. Sow only after that, and only a lawful crop.
Common questions
In what order do I hang the light, fan and filter?
Hang the filter and fan high on bars rated for the weight, pulling air through the filter and out, then hang the light on ratchets beneath them. Open a low intake so the fan is not sucking the walls in. A clip fan over the leaves comes last.
Do I assemble the tent in another room?
Assemble it where it will stand. A dressed 120 cm tent is awkward to carry, and GroWell warns against building on carpet and then dragging it. Leave about 20–30 cm for zips and ducting. If the ceiling is only just 200 cm, measure before the poles click: a roof duct will not fit.
When do I take the dome off?
Take the humidity-dome lid off as soon as shoots appear, which is the RHS line, and open the vents before that if the inside is dripping. Leaving the lid on for a few more days is how damping off starts. The LED bars can stay. The sealed, wet lid should not.
Do I need a thermostat on a heat mat?
You need a way to stop the mat cooking the plastic and the compost. The AC Infinity kit’s mat is reported as a dial, and one UK buyer melted the dome on the lowest setting. A separate thermostat kept dry, and rated for 230 V, is the safer pattern. Do not leave a mat against the dome overnight on hope.
Why are my seedlings collapsing?
Collapse at soil level, with a thin brown stem, is damping off. It comes from humidity, crowding and poor airflow, not from a lack of fertiliser. Remove the cover, thin the seedlings, water less often, and clean the tray before you sow again. Turning the heat mat up makes a wet dome worse.
Where does the duct go?
The duct leaves through a high port and takes the shortest path out, with the fan arrow pointing out of the room. A long loop adds heat and noise. Do not crush the duct flat, or the fan will labour.
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 seven listings on 19 October 2026.
- RHS, How to sow seeds indoors (retrieved 19 October 2026)
- Misuse of Drugs Act 1971, section 6 (retrieved 19 October 2026)
- CPS, Drug offences (retrieved 19 October 2026)
- GOV.UK, Drugs penalties (retrieved 19 October 2026)
- Electrical Equipment (Safety) Regulations 2016 (retrieved 19 October 2026)
- OPSS, YIKEDAN LED grow light 2408-0204 (retrieved 19 October 2026)
- CANNA UK, PK 13/14 (retrieved 19 October 2026)
- One Stop Grow Shop, beginner tent setup 2026 (retrieved 19 October 2026)