Ideal temperature for seedling

[PeterMParticipant]

Evening all.

I sowed some lettuce seed about 2 weeks ago and pricked them out, once they appeared, into a module tray (fairly deep). I purchased a 4-meter long soil warming cable and set it on a shallow layer of damp sand, in an insulated plastic tray (2ftx2ft). I covered the wire with more sand (about 5cm) and then placed a few sheets of newspaper and a plastic sheet over this. I then placed the Lettuces on this heated tray, hoping that this would provide enough warmpt for strong growth.

The lettuces don’t seem to have grown at all – which has got me wondering if the temperature of the medium(compost) is warm enough. The greenhouse is pretty robust and at the moment is at about 10 degrees. The heated tray does not really feel warm to the touch but I suspect is a couple of degrees higher.

So is my growing medium warm enough? If not what is the optimum temperature? What do others use to get higher temps?

Here is a link to the wire i purchased: https://www.amazon.co.uk/gp/product/B005N96OSA/ref=ppx_yo_dt_b_asin_title_o02__o00_s00?ie=UTF8&psc=1

[VintherParticipant]

Hi Peter,

This is my first season of no-dig and Charles’ gardening principles, and I’m following Charles’ 2019 Calendar, so today (Valentine’s day) is the big sowing day for the first set of crops. I’m going to germinate the seeds indoors and prick them out into module trays, and the move them to my electrical hot bed in my unheated greenhouse. My hotbed is 60×120 cm and powered by a 300w heat cable burred in sand. Pretty much the same setup as you have. I’ve added a temperature regulator to my hot bed, as 300w is a bit hefty most of the times, and when the ambient temperature is mild (5-10 Celsius) the heat is only switched on some of the time. Charles’ hotbed is made of fresh horse manure, and I remember correctly the soil temperature in his module trays were about 20 Celsius (at least the day he made his video).

I see you heat cable is 25w, and I suspect this is a bit at the low end. Have you measured your soil temperature?

Regards
Erik

[peteParticipant]

personally I would have taken it off after they had germinated. They may need heat to germinate but most seedling then do best at a lower temperature.

[tdcanamParticipant]

From what I have found, 72 F is ideal for lettuce germination. I am new to farming, so I do not have years of experience behind me. I built a germination chamber in my basement, mostly for growing in the summer. Here in Canada, it gets quite hot in the summer and if your soil/medium is above 80F, your seeds, apparently, will not germinate. Also, I have read that if you can have them under non-heat producing light, the germination rate is much better. (I have also read that red light is best, but this seems a little excessive.)

[Author]

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