The Cottage Smallholder

stumbling self sufficiency in a small space

Germinate seeds fast with an electric propagator

electirc propagatorI’m determined to set some of my seeds tomorrow. I have a small electric seed propagator, the cheapest one from Homebase. It has no thermostat nor any bells and whistles. Over the past three years, this willing donkey has germinated hundreds of seeds and has become an old friend. Admittedly I am not asking him to germinate really crusty coated seeds, such as those from the palm plant. But C.P. (Cheap Propagator) has our future in his warm embrace. He is perfect for germinating tomato, sweetcorn and cucumber seeds.

An electric propagator is a good investment as it speeds up the germination process enormously. As C.P. only accomodates one seed tray at a time, the next ten days will be a bit frantic but not as bad as it used to be.

I use seed trays with separate cells. Not the trays with the small 1″x1″ cells. I start with the next stage up (2″x2″). With tomatoes, I sow a couple of seeds in each cell, thinning them by removing the weaker seedlings a week after they have emerged. Plants produced in trays of cells are easier to nurture later on as they don’t need to be pricked out (what is pricking out? See Tricks and tips below). Their roots are undisturbed so they have a better chance of developing into sturdy plantlets. The big drawback is that filling the cells can a bit of a palaver. The cells are filled with potting compost and then watered. The compost tends to sink. It is then topped up and, finally, when all cells are level, sowing of seeds can begin. There is no point in trying to rush this stage.

In the olden days, each tray was prepared separately as requires and time permitted. The propagator could sit empty for several days before I found the time to fill the next tray of cells with compost and sow another batch of seeds. Everything suffered. The seeds didn’t get the optimum time to grow into strong baby plants before they were planted out. I felt overwhelmed and Danny secretly fretted over the size of the autumn harvest of tomatoes.

I now have a system. I fill all the seed trays that I will need for the planting season at the same time. I use John Innes seed sowing compost (this feeds the seedlings for the first three weeks) and they are potted on to John Innes plant and seedling compost before planting out in May. The trays wait in an orderly row in the greenhouse. I sow the seeds in the first tray and pop it into the propagator. This sits on a south-west facing windowsill in the cottage.

I mark each prepared tray with its eventual contents and put the relevant pack of seeds beside it. I return home at lunchtime, make a sandwich for us both and check the propagator.

As soon as the seeds emerge, the tray is whipped out and I cart it down the garden to the greenhouse. Usually I put an ordinary propagator lid over the seedlings for a day or two for extra protection, even in the greenhouse. The difference in temperature from sunny snug cottage windowsill to greenhouse can shock the seedlings and set them back.

Then I sow the seeds in the next tray and bring them back up to the cottage and the welcoming arms of our trusty C.P.

Useful links:

Homebase no longer stocks my propagator but a much more expensive one.

I’ve found a 8 watt electric propagatorsimilar to mine on Amazon.

There’s also a really great windowsill propagator on the Harrod Horticultural site.

Tricks and tips:

  • What is pricking out? Transplanting germinated seeds from the seed bed to small pots or large seed tray cells.
  • If like me your propogator has no temperature control you can check the temperature placing an ordinary outdoor thermometer under the lid.

  Leave a reply


  1. Thanks for the info on seed propagation and in particular your use of the heated propagator…I will definitely seek one out. I’ve sown lettuce seeds in the tunnel and they’ve come up alright, but now need help!

  2. Fiona Nevile

    Hi Colette

    A heated propogator is a sound investment and really comes into its own when germinating tomato and parsley seeds.

    Thanks for leaving a comment.

  3. Abit late, but have just read your very useful tips about using a heated propagator.Love your system of getting everything lined up! Hope to get a C.P. tomorrow. I started my tomato seeds off in the airing cupboard. They’re now in the greenhouse but this is unheated. They’re about 5″ high.In view of the very cold weather do you think they need some heat?

  4. Fiona Nevile

    Hi Jo

    My teeny seedlings are in the greenhouse and seem fine. I am not providing extra heat for them. Growth may be slower but I reckon that I get stronger plants in the end.

    Would be very interested to hear how you get on both with the tomato plants and the C.P.

  5. Eileen Wheeler

    What other vegetables can you grow from seed in an electric prop. I have a small veg patch but grow various veg to provide for my families seasonal needs

  6. Fiona Nevile

    Hi Eileen

    You can germinate all vegetable seeds in an electric propogator. The heat speeds up the germination process.

    You do need to move them out of the propogator as soon as they appear to a warm bright spot to avoid the seedlings going leggy.

  7. john kolosowski

    when the seeds have germinated in the propagator when can you move them directly in to the green house

  8. I am looking to buy my first electric propagator to grow tomatoe, cucumber, pepper and any other vegetable seeds that I can. There are so many propargators on the market it’s knowing which one to buy? Would it be better to regulate the temperature in order to successfully germinate a wider range of veg seeds? I have recently purchased an unheated lean-to-greenhouse to grow my seeds on but need to propargate seeds first. Can anyone please help me? Thanks, Roy.

    • Fiona Nevile

      Hi Roy

      Our basic propogator doesn’t have a thermostat but if I was to buy one again I would definitely get one with a thermostat. Ours is fine but I’ve had (with the exception of tomatoes and peppers that can be started in mid January) great results with pots covered in small plastic bags on a sunny windowsill.

  9. John Wild

    I am new to using a heated propagator. It looks successful as seed are through within a week. But how I stop them getting very leggy ? Will they fill-out once pricked out into trays ? Should I not have used all-purpose compost ? All advice will be much appreciated.

    • Fiona Nevile

      Hi John

      I have most success with multi purpose compost (recommended by Sarah Raven for seeds). Give them as much light as possible, they will fill out when pricked out into trays and you can put them in fairly deep too – up to the first leaves.

  10. I recently bought a propagator. I have planted seeds but I find the glass cover is continually covered in moisture. I clean this off daily. Any advice please. I have read your article and found it very helpful Regards Tom

    • Fiona Nevile

      Hi Tom

      I use the condensation to water the seeds. Obviously if they don’t need it, I wipe it off. I find the condensation good as the warm moist environment seems to help germination.

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