Propagators

Propagators — Heated and Unheated Seed Trays for Quick Germination

Best for: Anyone wanting to start seeds and cuttings indoors without waiting for spring weather to sort itself out

A propagator is a clear container that does one simple job: it creates a warm, humid microclimate where seeds germinate and cuttings root faster and more reliably. No greenhouse needed, no guessing the temperature, no losing half your seedlings to cold or damp. Whether you choose an unheated model for basic humidity control or a heated propagator with thermostat, you're buying consistency — the thing seeds actually care about.

How it compares

Propagators split into two clear camps:

• Unheated models — Simple clear plastic containers with vented lids. Rely on ambient warmth and sunlight. Cheaper, smaller, better for mild conditions or hardy varieties.
• Heated propagators — Built-in heating element (typically 13–22W) with thermostat control. Maintain steady 20–25°C regardless of what's happening outside. Worth the extra for early-season sowing or heat-loving plants.

Premium models cost ten times more than basic ones — but that extra usually buys you thermostat control, better heat distribution, and modular design. Entry-level heated propagators do the job without the premium markup.

Usage guidance

Getting started
Fill your propagator with fresh seed compost, sow your seeds or insert cuttings, water in lightly, and close the lid. The trapped humidity does most of the work for you.

Temperature management
Most seeds germinate best between 20–26°C. Heated models maintain this automatically; unheated ones work fine on a warm windowsill or in a heated room. If you're using a heater, dial it in and leave it — thermostat control means no faffing.

Humidity and air
This is where the vents matter. Too much humidity breeds fungal disease. Open the vents gradually once seedlings show their first true leaves. After a few days, remove the lid during the day. After a week, take it off completely. This hardening-off process prevents shock when they hit the garden.

Common pitfalls
Overwatering kills more seedlings than anything else. Keep compost damp, not waterlogged. High temperatures cause leggy, stretched growth — monitor and adjust. Use clean containers and fresh compost to avoid damping-off disease.

Technical specifications

• Unheated models: Clear plastic tray with vented lid. No power required. Maintains ambient temperature plus modest humidity gain.
• Heated models: Watertight plastic tray, clear vented lid, built-in heating element (13–22W typical).
• Temperature range (heated): Thermostat-controlled 18–25°C, with heating element raising temperature by approximately 8°C above ambient.
• Ideal growing conditions: 20–25°C, 60–80% humidity, good air circulation via vents.
• Size options: Compact windowsill models (fits standard indoor spaces) through to large multi-tray units (greenhouse-suitable).
• Capacity: Entry-level propagators typically 4–7 individually-vented cells; larger models offer three-tray sections with independent control.
• Power: Heated models require mains plug socket. No additional equipment needed.

Who this is for

• First-time seed growers who want to avoid the frustration of cold germination failures
• Anyone growing heat-loving plants — tomatoes, aubergines, chillies, peppers — that need a long season indoors
• Growers without a greenhouse or polytunnel who need seedling space on a windowsill
• People propagating cuttings and wanting reliable root development without guesswork
• Seasonal growers sowing early-spring varieties and wanting to beat the weather

Budget growers appreciate entry-level heated models; experienced growers often go for modular designs with better thermostat precision.

Our take

A propagator is honestly one of the smartest early buys if you're growing from seed. It's not fancy kit, but it removes a real variable — temperature — and that alone cuts your failure rate significantly. Heated models cost more upfront but repay that investment within a season when you're not buying replacement seedlings or losing germination batches to cold snaps.

Good time to buy while stock lasts. Does exactly what it should: give your seeds and cuttings the warm, stable, humid start they need.