Collection: 4 tier greenhouse

What a 4 Tier Greenhouse Is

A 4 tier greenhouse is a slim steel or aluminium frame carrying four stacked shelves under a clear PVC or polycarbonate cover. The footprint stays close to half a square metre, which is why it fits beside a door, against a balcony rail or along a wall where nothing larger would go. A roll up or zipped front panel opens the whole face for watering and picking.

The format suits anyone growing in a small space: a first year gardener raising seedlings, a flat dweller with a balcony, or an experienced grower who needs somewhere to harden off before planting out. Four shelves also allow plants at different stages to be kept apart without needing separate structures.

A 3 tier greenhouse works the same way with one shelf fewer and a lower profile, which can matter under a window or on a covered balcony.

What to Look for When Choosing

Frames vary more than the covers do. Powder coated steel is heavier and stiffer, while aluminium is lighter and will not rust if the coating is scratched. If you plan to stand full containers on the upper shelves rather than seed trays, check the stated shelf load before ordering.

• Removable shelves let you clear the lower section for tall crops such as chillies or bush tomatoes.
• Mesh or wire shelves drain freely and let air move around the base of each pot.
• A reinforced zip and a second row of eyelets make a noticeable difference in wind.

Covers are the part that wears out. A replacement cover is far cheaper than a new unit, so it is worth checking that one is available for the model you choose before buying.

Where to Put It

A wall facing south or west gives the longest hours of direct light and shelters the back of the frame. Standing the unit against a wall rather than free in the open also cuts the wind load considerably, which matters because these frames are light enough to move in a gust.

Weight is the trade off for portability. Pegs, ground weights or a strap to a rail are not optional on an exposed balcony or roof terrace. If your site is genuinely windy, a rigid mini greenhouse or cold frame may hold up better than a covered tier frame.

Growing in a Tiered Frame

Heat builds quickly inside a small enclosed volume, and on a bright spring day the temperature at the top shelf can run well above what seedlings tolerate. Open the front during the day and close it before evening. This is the single most common cause of losses in tiered frames, and it is entirely avoidable.

Water is the other difference from a walk in house. Small pots on open shelving dry out fast, so daily checking through summer is normal rather than excessive.

When to Move Up

A tier frame is a starting point rather than a limit. Once you are raising more than the shelves hold, or you want to work inside rather than reaching in, the next step is usually a small greenhouse under 5 m2 or a slim frame for a balcony or patio.

Many growers keep the tier frame afterwards and use it for hardening off, which is what it does most reliably.