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Will they grow?

Posted: Mon Jul 09, 2018 4:47 pm
by Westi
Re: Lettuce & Salad leaves.

Due to the temperature very few of my seed has germinated. Will they just start to germinate when conditions are more suited for them or should I re-sow? I know the poor little seed has been baked a bit but that happens when in their packets in the shed as it gets mighty hot in there at times, but they are still viable when sown. I continue to water the beds as well.

I see that the red leaved ones are popping up slowly, but no sign of anything green! Cheers in advance!

Re: Will they grow?

Posted: Mon Jul 09, 2018 7:10 pm
by robo
I've just planted a tray of little gem I've put it under a bench were it can get a bit of shade as well as a bit of sun

Re: Will they grow?

Posted: Mon Jul 09, 2018 8:39 pm
The last sowing of lettuce has germinated and been planted out this week. I kept it in the shade on the floor of the greenhouse. I've noticed that seed I've got left from previous years quite often fails to germinate.

Re: Will they grow?

Posted: Wed Jul 11, 2018 12:40 am
by sally wright
Dear Westi,
if lettuce seed suffers from too much heat in the packet or seed tray this can stop germination from happening. It is an interesting thing that naturally prevents the seedlings from being fried in the summer. A lot of biennial plants have this adaptation it is to prevent premature germination between seed fall in late Spring/early Summer and the best time for them to germinate (in their opinion) which is generally late Summer to early Autumn. Spinach, parsnips, pansies and violas also suffer from this condition.

Generally at this time of year lettuce seed should be sown in a cooler period with temperatures of no more than 20C. If I am trying to germinate seeds that suffer from this high temperature inhibition I will cover them in some shade netting and put the trays in the shade under a tree or a shady nook on a north facing wall. Mist or sprinkle them with water two or three times a day to try and keep the compost cool.

The real snag is that if lettuce seeds have suffered from a baking then they will fail to germinate for at least 6 months. I once left my seed box in the greenhouse for a weekend and failed to germinate over 20 (250 seds/pkt) batches of violas and pansies. So I have learnt this lesson the hard way. It sometimes mentions on a lettuce/spinach seed packet that they are best suited for Spring and Autumn sowing and this is because they will not germinate well in the heat of summer. I don't know if this will work but you might be able to break the high temperature dormancy of your lettuce seeds by putting the seed tray in the fridge for a week or two and trying again in the shady spot as above.
Regards Sally Wright.

Re: Will they grow?

Posted: Wed Jul 11, 2018 6:26 pm
by Westi
Cheers Sally!

That is very interesting. I could find lettuce popping up in next years rotation then? I've started some more today at home & put the tray on the patio under the umbrella & my phone is saying lower temps for a bit, so could be luckier. No rain showing on the phone but the BBC weather is saying storms maybe on Friday - fingers crossed!

Re: Will they grow?

Posted: Wed Jul 11, 2018 8:26 pm
by Primrose
I sowed some mixed lettuce seeds at the beginning of the hot weather in a shadier place than usual and kept the soil very moist. I wasn,t expecting them to germinate but a lot of them have done so. I suspect if I'd had sown them in a spot which was exposed to baking sun all day they would have just fried. I,ve sown some kohl rabi seeds today in a tray which I'm keeping in a shady potting shed area in the hope they will germinate.