You choose a grow tent by two measurements first: the floor area, which decides how many plants fit, and the height, which decides how tall they can grow. As a guide, without training a 60x60 cm tent holds 2–3 medium-sized plants, an 80x80 cm tent 3–5 and a 120x120x200 cm tent 6–12. Then comes quality: a metal frame, thick fabric with a reflective lining and zips that keep light in and out.
In brief
- Height: lamp, pot and the gap to the tops take up 70–100 cm; below 160 cm plants stay small.
- Quality: metal corner joints, Oxford fabric of 600D or more, light-tight seams and zips.
- Ports: duct sockets matching the extractor fan (100–200 mm) and low intake vents with mesh.
- Underneath: waterproof floor tray and saucers to protect the floor.
- Location: a room at 15–25 °C, a socket nearby and space to work around the tent.
Standard sizes and usable height
Grow tents come in a handful of standard sizes. Choose the floor area by number of plants and technique: with many small plants more will fit, with large trained plants a few are enough. The guide on how many plants fit in a grow tent goes into detail.
| Size (cm) | Area | Common heights | Medium-sized plants | Suited to |
|---|---|---|---|---|
| 60x60 | 0.36 m² | 120–160 cm | 2–3 | first grow, autoflowers, cuttings |
| 80x80 | 0.64 m² | 160–180 cm | 3–5 | small grows for personal use |
| 100x100 | 1 m² | 180–200 cm | 4–9 | medium-sized photoperiod plants |
| 120x120 | 1.44 m² | 200 cm | 6–12 | photoperiod plants, SCROG |
| 240x120 | 2.88 m² | 200 cm | 12–24 | larger grows with two lamps |
For usable height, subtract about 70–100 cm from the tent height: that goes on hangers and lamp (15–25 cm), the pot (25–35 cm) and the gap between lamp and tops (30–45 cm for many LEDs in flowering). In a 140 cm tent the plant should therefore stay under 40–70 cm, in a 200 cm tent under 100–130 cm. Photoperiod strains stretch by 50–100% in the first weeks of flowering, so 180–200 cm of height is worth having.
Quality: what to check
Two tents of the same size can last one grow or ten years. Before you buy a grow tent, check these points:
- Frame: steel poles with metal corner joints, not plastic; the frame must carry the lamp, carbon filter and extractor fan, which together weigh 12–25 kg in a 120x120 tent.
- Fabric: Oxford of 600D or more (the higher the number, the thicker the fabric), with no pinholes and no strong chemical smell.
- Reflective lining: Mylar or a silver coating, pulled tight with no folds that create shaded spots.
- Seams and zips: double seams and sturdy zips covered by a flap, because that is where light gets in and out.
- Doors: a wide front opening; from 120 cm upwards a side door is handy.
The simplest test: during the day, with the room lit and the lamp off, look from inside the closed tent for pinpoints of light at seams, corners and zips. Those are exactly the spots that disturb the 12 hours of darkness in flowering.
Ports for air and cables
A good tent has duct sockets at the top for exhaust air, low vents with insect mesh for passive intake and a separate port for cables. The sockets must match the diameter of the extractor fan and filter (100, 125, 150 or 200 mm) and have a drawstring that closes tightly around the duct.
- Hang the carbon filter and extractor fan at the top, where warm air collects.
- Run the duct out through the socket closest to the fan, on a short route with few bends.
- Open the low intake vents: their total area should be at least twice the cross-section of the exhaust duct.
- Set the fan so that the tent walls are pulled slightly inwards: this shows a slight negative pressure, which also keeps odours in.
Sizing the airflow, mounting and noise are covered in the guide to the grow tent extractor fan.
Floor tray and floor protection
Almost all tents have a waterproof floor tray with a raised edge, ideally removable for cleaning. Do not rely on it alone: stand each pot on a saucer or tray that catches run-off and empty it after every watering, because standing water raises humidity and attracts fungus gnats. On parquet or carpet, lay a waterproof sheet under the tent.
Light and extraction to match the size
Choose the lamp and extractor fan together with the tent. The table gives starting values for modern LEDs, about 300–400 W of real power per m², and for extraction: the airflow you need is the tent volume × 60 air changes per hour × 1.3–1.5 margin for filter and ducting; in brackets, the recommended rated airflow of the model.
| Tent (cm) | Real LED power in flowering | Airflow needed (rated) | Duct and filter diameter |
|---|---|---|---|
| 60x60x160 | 100–150 W | 45–52 m³/h (100–200) | 100 mm |
| 80x80x180 | 180–250 W | 90–105 m³/h (150–250) | 100 mm |
| 100x100x200 | 300–400 W | 155–180 m³/h (200–350) | 100–125 mm |
| 120x120x200 | 400–600 W | 225–260 m³/h (300–400) | 125 mm |
| 240x120x200 | 800–1,200 W | 450–520 m³/h (600–800) | 150 mm or 2 × 125 mm |
Choose an extractor fan with a speed controller: run it at 50–70% and you have spare capacity for hot days. Fan, filter and duct of the same diameter come ready matched in the air extraction kits.
Where to put it indoors
- Room temperature: ideally 15–25 °C. With the light on, the tent runs a few degrees warmer than the room; lofts under the roof get too hot in summer, cellars are cold and damp in winter.
- Exhaust air: you need a way out for it, such as a window or another room, with the shortest possible duct.
- Power: a nearby socket protected by a residual current device (RCD), a good-quality power strip off the floor, no extension leads on the floor where water can reach.
- Working space: leave 40–60 cm in front of the door and a few centimetres between tent and wall for ducts and sockets.
- Noise: extractor and circulation fans run day and night; a silencer and anti-vibration mounts help if the tent is next to a bedroom.
- Floor: level and water-resistant; a tent full of wet pots is heavy.
Frequently asked questions
What size grow tent do I need for 4 plants?
For 4 medium-sized plants an 80x80 cm tent is enough, with about 40x40 cm per plant and 11–15 litre pots. If you want bigger plants or train them with topping and LST, choose a 100x100 or 120x120 cm tent.
What should a good grow tent have?
A steel frame with metal corner joints, thick fabric with a reflective lining, light-tight seams and zips, sockets of the right diameter and a waterproof floor tray. Always do the light test before your first grow.
Can I keep a grow tent in the bedroom?
You can, but you have to accept the noise of the extractor and fans, light escaping through the vents and the extra heat and humidity. A separate room, such as a box room or a dry, heated cellar, is usually more practical.
Does a grow tent let odours out?
The fabric alone does not hold back odours. A carbon filter on the extractor fan does, keeping the tent under slight negative pressure: in flowering, without a filter, the smell escapes and can bother the neighbours.
Tents, lighting and extraction already sized to each other are in the complete grow tent kits; what they contain and cost is explained in the guide to the grow tent complete kit.
Updated on 13 October 2026.