Electric Heated Propagators

Electric Heated Propagators

Even though it is cold outside, even snowing, late winter and early spring is an ideal time to sow many vegetables – especially those that enjoy long summers like tomatoes, peppers, and aubergine.

Electric heated propagator sowing

I have found my heated propagator to be a good investment, as it speeds up germination and makes the whole process more reliable. This means I can grow more, as there is a higher turnover of pots of the kitchen windowsill.

The Advantages of Electric Heated Propagators

  • Seeds germinate faster in a heated propagator
    Examples include tomato plants or cucumbers germinating in 2 days rather than 7 to 14 on a sunny windowsill. If warm space is an issue, this means a gardener can grow more plants, as there is less time to wait for one batch of seeds to germinate before the next batch can start.
  • Electric propagators give gardeners more options
    This could include helping cuttings become established in autumn, or starting seedlings in January.
  • Savings on seed
    Seeds germinate more reliably in heated propagators so you need less.
  • Avoid heating a whole greenhouse
    Rather than heat a whole greenhouse, a large heated propagator can be a very efficient way of growing seedlings through late winter or early spring.
  • Electric propagators save work
    Germination is faster and requires less manual intervention. They eliminate the hassle of putting seeds in an airing cupboard or on a sunny windowsill. Seedlings have a place outside of the home ‘living space’.
  • They are fun
    There is satisfaction from having a gadget that works, that helps speed on nature and reduces the impact of weather. A gardener can feel more successful with heated propagators.

See electric heated propagators on Amazon UK.

Considerations Before Buying

  • After germination, where do the seedlings go?
    Electric propagators are most useful for gardeners with greenhouses, growhouses, hotbeds, or cloches. Otherwise, when seedlings are moved the shock of cold may negate the advantage gained by fast germination. You may like to see this page on plastic greenhouses and growing tunnels.
  • The same results can be achieved with a sunny windowsill or airing cupboard
    These may not be quite as fast as heated propagators, but nevertheless still pretty fast and reliable.
  • The cost of electric propagators
    Depending on functionality and size, the price range is upwards from £20 with some best selling brands at nearer £200.
  • Care and maintenance
    Supervision is still needed with heated propagators. Heated propagators do not cool down the soil on sunny days – they simply turn down the heat (if they have a thermostat). This means that in hot weather the gardener will need to open the air vents. Equally, in very cold weather, it may still be necessary to cover heated propagators, for example if sited in an unheated greenhouse. The heating element may be overwhelmed if outside temperatures plummet too low.
  • Space
    It may be obvious to say, but electric propagators need to be put somewhere. If the only location available is a windowsill in your home, then this may be hot enough anyway for good germination. Heated propagators are most useful in greenhouses, or cold rooms with good light in a house, a garage, or garden shed.

How to Use a Heated Propagator

Please watch the video, or if you prefer, scroll below to read on:

How To Use A Heated Propagator
How To Use A Heated Propagator

This video features the Sankey Growarm 100 heated propagator. For the last couple of years it has done a good job, significantly speeding up germination times and making germination more reliable – meaning I need to sow less often and using fewer seeds.

This model does not have a thermostatic temperature control to measure and regulate temperature. When the weather warms I take the plug out, preventing it getting too hot inside. Out of the box it comes with a plastic lid, two seeds trays, a capillary matt, and the base that contains the heating elements.

First step is to prepare the pots or seed trays. Avoiding homemade compost is best, as it can contain weeds. A fine crumbly shop bought compost is ideal. After filling the pots, I soak the soil using water from the outside tap – fresh water helps to avoid disease.

Next step is to wet the capillary matting under a tap, and place on the bottom of the heated propagator. The matting provides more moisture to the growing environment, but also helps to keep the bottom of the heated propagator clean.

I’m sowing tomato, pepper, and inca berry seeds, for later growing on in our polytunnel. I space out three seeds per pot, and then cover with a fine layer of vermiculite. If all three seeds germinate I will will divide and grow on in separate pots. There is no need to water for further watering as there is enough moisture in the compost.

When all the pots are prepared, the final step is to cover the propagator with its lid. Closing the vents on the propagator creates a humid growing environment ideal for germination. With closed vents, the pots do not need watering.

I place our heated propagator on a bright kitchen windowsill that only a receives about two hours sunshine a day. It is a bright location, but the lack of direct sunlight and warmth makes it an ideal spot for the heated propagator.

As soon as germination starts, I gradually open the vents a little each day to gently acclimatised the plants to normal conditions.


When the seedlings have developed true leaves, we remove them and grow them on the same windowsill but outside of the propagator. The propagator is then free for the next sowing.