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Best heated propagators

We've tested heated propagators to give you a head start on sowing seeds and taking cuttings while it's chilly outside. 
Ceri ThomasEditor, Which? Gardening

Ceri studied horticulture at university and has spent her career editing gardening content. You shouldn't have favourites but she loves sweet peas!

Trialling heated propagators

Heated propagators are great for improving the germination rate of your seeds and helping you get cuttings to root. 

They’re cheap to run, and you don’t need a lot of space for them as there are plenty that will fit on a windowsill. 

Our tests reveal the best ones to go for, and we give you a few tips on using them.

How our tests find you the best

We've tested 10 heated propagators

Eight had no thermostat and two had a fixed thermostat – these should turn off when they reach a set temperature.

Temperature

We checked how well regulated the compost temperature was (whether it got significantly hotter or colder than expected) and whether the temperature in different parts of the propagator was consistent.

Condensation

We assessed the amount that built-up on the inside of the lids with the ventilators closed and with it open.

Germination

We monitored how quickly our three sets of seeds came up and whether they all germinated

Best heated propagators

When testing heated propagators we looked for the models that regulated the temperature well, had good ventilation and would work equally well for cuttings and seeds. 

One of our Best Buys worked well for seedlings and cuttings and had great ventilation. Another gave great options for seed sowing.

Which? members can log in now to see the full results and which are our Best Buys. If you’re not a member, join Which? to get instant access.

Product namePriceDimensions L x W x H (incl. lid) cmOverall ScoreInstructionsSuitable for seeds and cuttingsTemperature - how well regulatedTemperature - evenessGermination rateVentilation
EarlyGrow Heated 3-Bay Windowsill PropagatorSQUIRREL_TEXT_50020605

EarlyGrow Heated Propagator, MediumSQUIRREL_TEXT_50015912
Garland One Top Electric PropagatorSQUIRREL_TEXT_50020602
Garland Super 7 Electric Windowsill PropagatorSQUIRREL_TEXT_50020604

Garland Trio Top Electric Windowsill PropagatorSQUIRREL_TEXT_50020603
Sankey Electric Propagator 38cm Growarm 100 KitSQUIRREL_TEXT_50020600
Selections Jumbo Windowsill Heated Plant Propagator (80cm)SQUIRREL_TEXT_50020601

Stewart 38cm Premium Thermostatic Control Electric PropagatorSQUIRREL_TEXT_50020598
Stewart 38cm Essentials Electric PropagatorSQUIRREL_TEXT_50020599

Ignores price and is based on: Instructions, 5%; suitability for seeds and cuttings, 10%; temperature regulation, 25%; temperature eveness, 25%, germination, 20%, ventilation 15%

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How to get the best from your heated propagator

Thermostats

  • Propagators can have a fixed thermostat which shuts off the heat at a fixed temperature, or no thermostat so the heating element stays on constantly. With no thermostat they heat the compost to around 8-10C above the ambient temperature and can overheat on a sunny windowsill or in very warm conditions. 
  • If your propagator has no thermostat, keep an eye on it and remove the lid, move it, or turn it off if it gets too hot. 

Using your propagator

  • Sow seeds and put cuttings into separate trays or pots and put these into the propagator. Never fill the propagator base with compost.
  • Keeping the compost evenly moist helps to maintain a more even temperature in different parts of the propagator.
  • Humidity can help with germination, but excessive condensation can promote mould growth once seeds start to germinate. Use the lid ventilation to minimise condensation, especially once germination begins, and shake water out of the lids periodically. Take them off altogether if necessary.
  • Once all the seeds in a tray or pot have germinated, move them off the heat so they don’t grow too tall and leggy.
  • If you take a lot of cuttings, check the lid height is sufficient to fit the sort of material you take, or you will need to cover taller cuttings with plastic bags and just use the heated base.

Take cuttings with the best secateurs

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