The Cottage Smallholder

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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.

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  1. What a lovely posting – and very practical too.
    I read Alan Titchmarsh’s advice on using a heated propagator (having just bought one)and he says you should put a layer of sterilised silver sand on the base of the propagator. I’ll ignore that and follow your method.
    I do like your system of preparing seed trays in advance.
    Thanks for your advice.

  2. Hi I’m growing begonia corms for first time in propagator. I mixed an all purpose compost with sharp sand watered and put in propagator . how often should I water ?

  3. Squirrel

    Hi, I have sown some viola seeds in a home made propagator, made from an empty plastic cake holder. I filled it with compost, sowed my seeds, and covered it with the clear top that came with the holder. I stood it on the kitchen window sill, and now they are starting to shoot. Would it be ok to move the propagator to the lounge windowsill, which has heating below it, and sun for most of the day?

  4. I am trying a heated propagator in an unheated greenhouse this year, but dont know when to start everything off.
    Should I wait for the spring so that after the seeds have germinated they can be ok in the unheated greenhouse ?
    I fear that any seedlings bought out of the propagator might get chilled if I were to start everything in this month which is February.
    Having said that the seeds will take a little while to germinate ?
    I have tried seed setting bedding begonias in previous years, without success so I am hoping that this year my results will be better with the heated propagator

  5. Hi, I’m using a propagator at the moment for chilli seeds. Do they have to be left on all the time or is it better to switch it off occasionally.

    • Fiona Nevile

      Hi Pete

      The temp needs to be constant so keep it switched on all the time.

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