Germination temperature

Why do different seed producers give different temperatures. Suttons say 15 to 18c and 10 - 21 days but Thompson & Morgan go for higher figures and longer germination times. Is it all about wait and see. I would have thought that a higher temperature would give a shorter gernination period.

I'm sometimes totally confused about what you are told to do. So maybe some advice fom those who have been there before.

harryb

 

Plenty info regarding optimum temperatures Harry if you follow this link.

http://tomclothier.hort.net/page11.html

 

Harry - I think it is a somewhat inexact science. I think companies like to quote conditions that worked well for them - and sometimes they just copy the information from another source that's wrong :D.

When I started gardening, I spent a long time on the internet looking at descriptions of plants and the conditions that they liked. I couldn't understand why so many sites said conflicting things. Nowadays I just look at a large number of sites and take a mental average.

I am currently growing some seeds and some annuals will all germinate at the same time. But as an example of the inexactness, I am also growing Brugmansia, where you have a small number of very large seeds. Typically one seed will germinate after say 6 days, then you might have to wait another three weeks for the next seed to germinate, and others will follow at intervals. This sort of thing happens with quite a lot of seeds.

 

I use cool, warm and hot.

Warm is in a propagator. It has no thermostat, but just provides gentle warmth. Sticking a clear plastic bag over the pot and putting it somewhere warm in the house (i.e. not a draughty windowsill) would be the equivalent. Nearly all my seeds go this route.

Cool is the same, but I don't give it any additional heat. Windowsill in the house (so temperature 17 - 20C), and then out to the unheated conservatory the moment it has germinated (but back into the [warmer!] unheated utility corridor on frosty nights). Onions, Brassicas, and anything that doesn't like the heat, or grows too "soft" with heat.

Then hot. That's either the airing cupboard, or an upturned polystyrene (i.e. open at the bottom) stood on top of the boiler. For example: I'm trying some seeds that want 35C for 9 hours a day ...

 

What needs 35C for nine days Kristen - that wouldn't be native to Yorkshire I think. :D

 

Bananas I think ... hang on, I'll fire up the Destructions list in Excell ...

Yeah, Musa sikkimensis. I probably got the low-down off Tom Clothier's site

 

Hello Harry
welcome to the world of the terminally confused :D Yours is a good question , in fact I have been doing a little research on germination temperatures. I have been looking at some commercial seed sites , the ones who sell directly to the nursery in 1000's of seeds not your packet of 20 for £1.99. For an example look at Thompson and Morgans commercial and retail sites below for a Marigold Durango seed - note same company same seed...

T and M Retail ( for me and you ).... 20 - 30°c
http://www.thompson-morgan.com/flowers/flower-seeds/annual-bedding-plant-seeds/marigold-durango-bolero/4243TM

T and M commercial for the nursery growers. 18 - 20°c
http://www.direct2grower.com/seeds1/product/40224243/1.html

Can anyone throw any light on this

I have listed 2 more commercial sites with lots of germination information - It can get very confusing
Personally I would go with Kristen and Peters advice - cool / warm / hot or take a rough average.

http://www.floranova.co.uk/index.php
http://www.panamseed.com/default.aspx

 

Hello Harry
welcome to the world of the terminally confused :D Yours is a good question , in fact I have been doing a little research on germination temperatures. I have been looking at some commercial seed sites , the ones who sell directly to the nursery in 1000's of seeds not your packet of 20 for £1.99. For an example look at Thompson and Morgans commercial and retail sites below for a Marigold Durango seed - note same company same seed...

T and M Retail ( for me and you ).... 20 - 30°c
http://www.thompson-morgan.com/flowers/flower-seeds/annual-bedding-plant-seeds/marigold-durango-bolero/4243TM

T and M commercial for the nursery growers. 18 - 20°c
http://www.direct2grower.com/seeds1/product/40224243/1.html

Can anyone throw any light on this

I have listed 2 more commercial sites with lots of germination information - It can get very confusing
Personally I would go with Kristen and Peters advice - cool / warm / hot or take a rough average.

http://www.floranova.co.uk/index.php
http://www.panamseed.com/default.aspx

 

Some good points of view. Thank you.

It seems like trial and error. As this is my first year at greenhouse gardenning I have made a note of all I've done so far. I will see what my success rate is and adapt for next season.

I have spent all weekend pricking out, very theraputic. I have just brought everything indoors as it's forecast -2c again tonight. 12 full seed trays in a seed tray carrier is no mean feat.

harryb

 

I've grown lots of all kinds of seed over the years and the thing that strikes me most is that you can only take those temperatures on the seed packet at face value.
Most common grown seed, ie. veg and flowers will germinate at varying temps. some will take longer at lower temps. but they usually germinate in the end.

I tend to think its only when you start to grow something a bit different from the norm that you need to do anything special, and in those cases its good to know the habitat and climate of where the plant concerned grows.

If its half hardy, gentle heat, say 18 to 25C
If its hardy, just normal temps.

The growing on temps are more critical than germination, I think.

 

This prompts another question.

Once germination is complete and seedlings are pricked out what minimum temperature will they be able to tolerate. I am setting up a propane heater in the greenhouse, just waiting for gas, so thinking of the fuel cost what is a safe temperature to set the thermostat at.

harryb

 

Hardy things - just giving them some protection is enough (they will mostly still survive outside). Onions, Brassicas, stuff like that. Don't give them "extra heat"

For tender things then 10C minimum. They will survive below that, but they will "stall" and take ages to get going again. Tomatoes, Melons, Peppers, Cucumbers. Aubergines - that type of thing

Things that grow outside happily, but are tender, will tollerate lower temperatures so long as they don't get frosted. Sweetcorn, Runner beans. But they grow so quickly it is easier to sow them just 2 or 3 weeks before you will plant them out (after last frost), and by then the nights are a lot shorter, so greenhouse temperatures don't fall close to freezing.

In terms of germination temperature, Tom Clothier's site (to pick one extreme example) says of Parsnip seed:

at 32F 82% germination, at 68F 89% germination - not enough to worry about? but at 32F they take 172 days! whereas as 68F they take 14 days. For me propagators provide more consistent and higher rates of germination, and in a shorter time period. But I don't use them for things that don't like the heat - they just start off soft and weak (albeit that they initially grow much faster!)
[hr]
I bring my tender things in for the night when it is cold (right through March, but sometimes even in April)

I have a "blow away" in the convservatory with a light bulb in it (a small heater would be better). I zip them up in that at night when it is not going to be too cold.

You need a Max/Min thermometer so you know what protection your greenhouse, and heater, gives compared to outside. I would guess (but that's all it is!) about 6C

 

Some great advice on this post.

This is only my second topic and already the information received has answered my questions.

Thanks

harryb