Lettuce Thermo-inhibition

If you would like advice from the Kitchen Garden editorial team, ask here. Steve, Emma or Tony will pop in with their best advice.

Moderators: KG Steve, Chantal, Tigger, peter

Colin Miles
KG Regular
Posts: 1017
Joined: Thu Nov 24, 2005 8:18 pm
Location: Llannon, Llanelli
x 10

Lettuce Thermo-inhibition

Postby Colin Miles » Sun Apr 12, 2020 7:34 pm

I am sure this has been covered before, but I couldn't find it in a search.

I rather foolishly sowed some lettuce seeds April 2nd in my greenhouse and it has been too hot for them to germinate - I believe anything over 80F will inhibit them. I can't remember whether it is a simple matter of putting them somewhere cooler or giving up on that lot and resowing.
0 x
Westi
KG Regular
Posts: 4671
Joined: Thu Oct 30, 2008 4:46 pm
Location: Christchurch, Dorset
x 801

Re: Lettuce Thermo-inhibition

Postby Westi » Sun Apr 12, 2020 7:41 pm

I would think you'd have a wee show by now from those you have sown, they are pretty quick up if happy. If not sown direct you could put the tray somewhere cooler just as an experiment but I would be re-sowing somewhere cooler.
0 x
Westi
Monika
KG Regular
Posts: 4252
Joined: Thu Jul 06, 2006 8:13 pm
Location: Yorkshire Dales
x 658

Re: Lettuce Thermo-inhibition

Postby Monika » Sun Apr 12, 2020 7:50 pm

I did the same, Colin, and only a few seeds have germinated. But as the forecast for the next few days is for considerably cooler weather (at least for us oop north it is!), they will probably come out now.
1 x
User avatar
John
KG Regular
Posts: 1603
Joined: Fri Nov 25, 2005 10:52 am
Location: West Glos
x 45

Re: Lettuce Thermo-inhibition

Postby John » Sun Apr 12, 2020 10:19 pm

If we are having a warm spell it is best to sow in the late evening when its cooler and then water with cold water.
John
1 x
The Gods do not subtract from the allotted span of men’s lives, the hours spent fishing Assyrian tablet
What we observe is not nature itself, but nature exposed to our method of questioning Werner Heisenberg
I am a man and the world is my urinal
User avatar
Johnboy
KG Regular
Posts: 5804
Joined: Tue Nov 22, 2005 1:15 pm
Location: NW Herefordshire
x 115

Re: Lettuce Thermo-inhibition

Postby Johnboy » Mon Apr 13, 2020 11:46 am

Dear John,
If lettuce seed are subjected to high temperatures germination locks up. I had this several years ago and I posted on the forum about it.
I planted an 80ft x 30ft tunnel with 6 benches of trays of 216 and in the second week in February I had just finished sowing and the afternoon was beautiful so my wife and I took off on a jolly and the temp in tunnel exceeded 120F and the whole lot locked up. It also ruined all the min/max themometers so I don't actually know how high the temp got. The trays were emptied out and resown and where we had discarded the waste the lettuces finally germinated in October!
Sihncrely,
JB.
3 x
JB.
sally wright
KG Regular
Posts: 695
Joined: Tue Nov 29, 2005 7:32 pm
Location: Cambridge
x 215

Re: Lettuce Thermo-inhibition

Postby sally wright » Mon Apr 13, 2020 2:38 pm

Dear All,
you could try putting the seed tray (in a plastic bag!) into the fridge for a month or so to try and overcome the inhibition. DO make sure that COOK's permission is sought before placing the tray inside though. This temperature germination problem can also occur if you have left the seed packet on the greenhouse bench and it has got hot. Then you can do the same with the seed packets; but I would leave them in there for several months.

This scenario can also apply to winter bedding seeds such as pansies, violas, primroses, polyanthus, auricula and forget-me-nots. For them sowing in cooler weather is advised and if not then sow in a shaded area and cover with shade netting as well. Mist frequently if possible.

Regards Sally Wright.
0 x
Stephen
KG Regular
Posts: 1551
Joined: Thu Feb 14, 2008 4:03 pm
Location: Butts Meadow, Berkhamsted
x 625

Re: Lettuce Thermo-inhibition

Postby Stephen » Mon Apr 13, 2020 8:52 pm

Cook's permission! :shock:
When my car entusiast friends put bits of engine in the dishwasher or oven they make sure their sparring partner is out!
0 x
Nothing is foolproof to a sufficiently talented fool.
sally wright
KG Regular
Posts: 695
Joined: Tue Nov 29, 2005 7:32 pm
Location: Cambridge
x 215

Re: Lettuce Thermo-inhibition

Postby sally wright » Tue Apr 14, 2020 7:17 pm

Dear Stephen,
in these uncertain times I doubt very much if COOK will be out for long enough for anyone to run a dishwasher with illicit items in it and not get caught.....
Regards Sally Wright
1 x
Stephen
KG Regular
Posts: 1551
Joined: Thu Feb 14, 2008 4:03 pm
Location: Butts Meadow, Berkhamsted
x 625

Re: Lettuce Thermo-inhibition

Postby Stephen » Tue Apr 14, 2020 7:49 pm

How true! :D
0 x
Nothing is foolproof to a sufficiently talented fool.

Return to “Ask the team”

Who is online

Users browsing this forum: No registered users and 3 guests