Lettuce germination problem

Hi all

Earlier this year (about March time) I sowed a lot of different lettuce/salad seeds and the germination rate was fantastic, in fact I couldn't plant them all out - had to throw quite a few away unfortunately!

Now it's got to the time when those lettuces are bolting and I have to replace them. About a month ago I sowed some more, and kept them indoors in a shady spot (still warm, about 19C). The germination rate was really bad - only a few sprouted out of 30+ seeds.

I only bought the seed packets this year and so they can't be out of date yet - can they?

Is there any reason why the same lettuce seeds would germinate so well in March and so poorly in July - and what can I do to get around this problem?

Thanks in advance!

Paddy

 

they might have gotten mouldy, an airtight container is best, but that has to be dry too-I made a mistake with some allium seeds I collected and didn't put them in the egg part of the fridge-it has one of those blue egg looking things that keeps it dry and fresh in the fridge-should have done that as I have lost the whole batch. They were in a tupperware tub but had no silica gel bags to put in there with them.

 

I reckon the seed should be OK. I've had close to 100% germination on Lettuce seed from Spring up to my most recent sowing a couple of weeks ago. My seed packet is several years old ...

So I think more likely too warm, or dried out / got too wet.

I germinate mine in a 1/4 sized seed tray with clear plastic "dome" (they actually fit my heated propagator, but I don't use the propagator this time of the year). They are on a west facing windosill and just get the sun from about 4pm onwards. The "dome" keeps the moisture in, so they don't dry out, and I don't need to water them after sowing until after germination. But it might just be luck on my part!

Chucking a small pot in a sealed plastic bag, and putting it somewhere that has light, is not in direct sun, and doens;t get too hot, should do the trick.

I expect you could "test" the viability of your seed by putting some on a wet small piece of kitchen paper in the kitchen or somesuch.

 

Hi Paddy

Strange. Lettuce seed usually retains its viability well, I find.

Perhaps you have to be a bit tougher with them. Once April is past, all my seeds have to take their chances outside.

I planted some Webbs Wonderfuls in a multi-cell tray on 19 July and virtually all had germinated by four days later. They were outside in a sunny spot, just covered with some netting to stop the birds digging them out. They're growing so fast now, it's almost visible!

 

Lettuce do not germinate above 20 degrees. Apparently, they germinate in about 3 - 5 hours, so at this time of year it's best to sow in the evenings and keep fairly cool until they appear.

 

I've sown my Webbs Wonderful direct into the soil, no problem at all with germination, just gotta keep an eye out for those damn slugs !

 

That's worth knowing, and explains a lot.

Good time of year to start Chinese veg though.

 

"Good time of year to start Chinese veg though."

The Chinese Cabbage I sowed a week ago even have monstrous seed leaves! I have high expectations of the finished product

 

That's a good bit of information that Blackthorn, thankyou

 

Thanks for the info!

I think it must be temperature, as I sowed them during that hot spell we had (if anyone can remember it now, sigh). Although I made an effort to keep them out of direct sunlight, it must have still been too hot for them.

I don't think the seeds are mouldy, as I always take pains to use dry hands when handling them, and they are stored in plastic sachets which are airtight.

I'll try some outside, in the cooler weather hopefully they should germinate.

Does the temperature you store your seed at make a difference? Should I be storing mine in the fridge?

Paddy

 

"Does the temperature you store your seed at make a difference? Should I be storing mine in the fridge?"

In the case of Lettuce probably not. They will remain viable for a number of years even if abused. Probably ...

But ideally you should put them in a Tupperware box in the fridge, which will extend their life. So that would be the best plan, all things being equal.

 

Thinking about it, my Lettuce seed were left over from last year and have been left in all that time, out in the greenhouse. I reckon they're pretty tough seed, but would also agree about the sowing temperature thingy.

 

There's a rather interesting table showing the influence of temperature on germination here >

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

I reckon lettuce seed must be one of the toughest, as I've sown seed that's five years old and still had very good germination despite it being stored in a plastic box that migrates between greenhouse and garden shed.

 

That's very useful DaveW.

Earlier this year I sowed two lots of mange tout peas about 8 weeks apart. The first germination was fantastic, the second pathetic. That was when we had a hot spell. I watered them religiously to no effect. That table shows a dramatic fall-off above 30C, so that explains that. I assume the non-germinating majority rotted.

This rather confirms my impression that there's more to successful continuity than just staggered sowing.

 

Fascinating DaveW.

Lettuce has 99% germinate from 32F to 77F, and then falls to 12% at 86F

68F - 77F is the optimum for most things, with Melons / Cucumbers germinating more quickly at 86F