Germination Stragglers -- what all causes them?

[Greatgardens]

It seems like every year I get a couple of varieties that are tardy in germination. This year it was Dubok and Kumato (OP). These were planted in exactly the same manner as several other varieties. The others started poking through in 4 days (my usual with bottom heat). The Dubok took over two weeks and finally started coming up. The Kumato 10 days -- not so bad, but compared to their "efficient neighbors" at 4 days, that's still pretty long.

I don't have any reason to suspect that the seeds were old or poorly processed. What goes "wrong?" Genetic? Something else seed-related? Just curious -- my "crop" doesn't hang in the balance.

-GG

[sjamesNorway]

It think part of it is probably genetic - certain varieties take longer. It also depends on the age and condition of the seeds, and how they're stored. Last year I'd given up on a variety with apparently old seeds, but because it was in a tray with other varieties, it was kept watered, went through "the cold treatment", and finally germinated after 4 weeks.

Steve

[rhines81]

+1 on the above ... I had some Guajillo peppers germinate in 7 days and others in 26-30 days. Same packet of seeds, but due to my neglect from not being at home, some cells (potting soil) dry out and then recover again once I am home to water.
Not happy with myself this year. I started more seeds in a baggie and coffee filter last week, the soil method is hit or miss for me with my traveling for work. Will see tomorrow if any germinated, if not they are stuck in there for another week.

[pmcgrady]

My Japanese tomatoes and peppers I'm growing this year were late bloomers, but they are making up for it!

[MissS]

I have found that different varieties germinate at different times. I now keep these records as part of my journal so that I don't start early and later germinating varieties in the same pack of cells. I find that it is difficult to care for young plants in the same pack that you are awaiting others to germinate.

[mobiledynamics]

4 Weeks. Man, but day 14, if I did not see germination, I would have sowed in another batch of seeds to germinate !

[Nan_PA_6b]

Could be a lot of reasons:
Individual differences between seeds.
A little more, or less, moisture in the seed.
One is buried more deeply.
The soil in one cell has more, or less, of some ingredient.
The heat mat has a cold spot.
There's a dry pocket in the soil in one cell.
The darned seeds are ornery and like to frustrate us.
Etc

Nan

[bower]

Age of seed definitely can be a factor. So where the nominal seed age is not the problem, I usually think about environmental conditions in storage or in transit that reduced the viability of the seed or 'prematurely aged'. Random things can happen - I'm thinking of a nice batch of pepper seeds I'd saved, that got left on the table where the sun shone on them... I got zero germination from this batch, and had to resort to an older seed lot.
OTOH I wonder if seed process can also play a part. I experimented one season with fermenting tomato seeds in a ziploc, didn't add any water, maybe not enough air either. Those seeds were slower to germinate and had more helmet heads as well, than any other lots of seed I've saved. I went to a mason jar system instead last year, adding water again, and got good seeds that germinated quickly and few helmets. So it's possible that the type of seed process can have an impact on germination too. Why?
- is it the rate of imbibing water that's affected? I always thought old pepper seeds were just dryer than the fresh and took longer to imbibe... or, is it that the seed coat fails to soften as it needs to do for the seedling to break out and seed to be easily shucked?
There are enzymes and hormones involved in the germination process, so it could be an effect of my ziploc process that affected for example levels of ABA in the dormant seed. Or that the RNA for seed coat softening enzymes was affected? Or just a physical effect on the seed coat that hardened it more than the usual.
I think i'm more confused about this than when I started.
I do think that genetic differences exist, but they're certainly minor for seeds that were saved the same way and germinated in the same conditions. Not more than 48 hour differences I've seen, and the not-so-good seed process affected all genotypes the same way, pretty much across the board.
This is interesting:
natuurtijdschriften.nl/download?type=document;docid=541131

[SueCT]

I had one batch of seeds a couple of years ago of Sophies Choice that was terrible. Have no idea why and every other variety did well that year. This year I may be seeing my first evidence of lower germination rates due to aging seeds. I have some sown a week ago today that I am still waiting for. I noticed that some of the seeds are now 5 years old. 7 days is kind of long for tomatoes on a heat mat in my experience. In the past I have gotten about 90% germination. It will be interesting to see if the overall germination decreases or just slows down.

[rhines81]

Originally Posted by rhines81

+1 on the above ... I had some Guajillo peppers germinate in 7 days and others in 26-30 days. Same packet of seeds, but due to my neglect from not being at home, some cells (potting soil) dry out and then recover again once I am home to water.
Not happy with myself this year. I started more seeds in a baggie and coffee filter last week, the soil method is hit or miss for me with my traveling for work. Will see tomorrow if any germinated, if not they are stuck in there for another week.

Well the 7 different varieties put in coffee filters and baggies last Sunday, were all 80-100% germinated (6 seeds in each) when I got home today. Some looked like they were a couple days old. Into the soil they go and they all lived happily ever after. Much better.

[mobiledynamics]

Thread bump. Just on my soapbox this evening.

For plant's we've grown, and germinated seeds from ~last year~, we're at 100% germ rate.

When your order seeds from a retailers, what germination rate is considered acceptable industry practice. Order some seeds from a retailer that was new to me. Question if the F1 seeds are F1. Some of the more popular variaties germinated fine. Some are either more like 25% germination rate.....

[zipcode]

Originally Posted by Greatgardens

I don't have any reason to suspect that the seeds were old or poorly processed.

-GG

So they weren't your seeds. Then you have every reason to believe they were older.
No respectable seed selling company renews their seed stock every year, it's not economical and makes no sense, at least for tomatoes, which can sprout fast even after about 5 years. So some will be from older some from newer stock.

Bu from my own seeds I noticed it's not always the same, there are factors that are just hard to predict, if you look at the seeds from one tomato you'll see a variance in seed size so not all seeds are starting equal and their mom is at fault ().