tomato seedlings

Seeds to Seedlings
I like to sow my seeds in weekly intervals.
This means that I can deal with just a few at a time – whether its germinating, transplanting or potting on.

It also means that for bush varieties, where tomatoes ripen over a short period, the harvest will be spread out over a few months rather than having all the tomatoes ripen at the same time – tall varieties ripen over a longer period.

This can be a bit hit and miss when temperatures fluctuate widely.
When kept at the same temperature (more or less around 20C), tomato seeds usually germinate around five to seven days. If temperatures are up and down a lot, it could take around seven to ten days.

Once seedlings start to show through the soil, create a humid atmosphere to help them discard their seed shell. This can easily be done with a hand sprayer/mister and a propagator is great for germination.

When seedlings arrive, lots of light and a temperature around 18C is ideal. If the temperature is much lower at night, below 10C, try not to over-water them as a combination of wet soil and cold conditions can cause problems.

If temperatures are too high (above 21C), soil is too wet and light levels are low, they’ll shoot up like rockets, So …

  • Lots of light
  • Soil just slightly damp (not constantly wet)
  • Temperature around 18C

When late spring and early summer arrive, it is much easier to manage seedlings because conditions are more favourable.

4 Responses

  1. Rhys Jaggar
    | Reply


    I’m about to try germinating seeds for the first time after 3 years of successfully growing plants bought at garden centres. I harvested seeds last year from my crop and am wondering what sort of ratio of seeds to plants desired you should plant?

    I’m soaking 25 overnight in seaweed extract and have a divider with 84 sections to germinate/propagate in. I got about 100 seeds last year, so plenty left if the first attempt is a botch up.

    Would I expect to get 5, 10, 15, 20 or 25 plants from 25 seeds as a novice? And what percentage of those, give or take (just an indication so I”m in the right ball park) which germinate successfully are likely to produce healthy, vigorous plants??



    • Nick
      | Reply

      Hi Rhys,
      You would expect around 20 out of 25 seeds to germinate (at least) and only the ones that look smaller than the others or have damaged seed leaves will not produce to their full potential.

  2. Trevor
    | Reply

    Hi Nick,
    Are you saying use something like a propagator (lid) AFTER seeds start to germinate to create a humid atmosphere?
    I’ve always read it’s best to start seeds off in a propagator and then remove the lid as soon as they germinate or else they’ll get ‘leggy’?
    I’ve always thought that this was a bit odd as even if you sow all the same variety at the same time some seeds will always germinate before others!
    What’s your take on this?

    • Nick
      | Reply

      Hi Trevor,
      It’s best to leave the lid on the propagator until most of the seeds germinate – the earliest ones will be a bit leggy and the last to arrive may struggle a bit with the seed shall after the lid has been removed.
      It’s a bit of a juggling act, especially when as you say, some varieties will germinate before others.
      Best wishes,

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