Seed fertility

[quirkas]

Is it me or is packet bought seed losing its fertility? Over years I have often successfuly bought seed used some and packed the rest in an airtight container stored in a cool dark place untill the following year. Some packets I have successfully sown from year to year I am finding now that the fertilty on even freshly bought seed is often poor. I read somewhere that soak the seeds in water overnight and the good ones will sink and the infertile ones float and can be discarded. Out of a packet of 50 or so freshly bought sunflower seeds less than 10 sank.

Are some companies/types better than others?

I did notice that on home saved seed the success rate is much much higher. I know it generally states on the packet that packaged for year such and such but that does not say how old the seed is.

What do others think?

Quirkas

[Geoff]

Vegetable seeds are controlled to a standard and I think the vast majority meet that standard.
As far as I know there is no official standard for flower seeds and I often think the performance is lower.
I don't think the float test applies to all types of seed.
Companies do vary and I guess Which? have tested and compared but I haven't subscribed for a number of years so I can't pass anything on. Years ago I stopped buying anything from Thompson and Morgan as I was being endlessly disappointed by their flower seeds.
I store many seeds from year to year, if you buy anything from Franchi (Seeds of Italy) you haven't much choice as the packets are so big. This year I have got some Nicotiana Langsdorffii to sort out because they were saved seed from 2009 so I sowed them thickly and that is how they have come up!
Are you sure your sowing technique hasn't changed over the years, in particular what sort of seed compost are you using. Particularly for early sowings I have a routine of using peat based compost, I fill the containers, water, water again with Cheshunt Compound, leave them to settle to the temperature where they are going to be sown (propagator, greenhouse, or whatever), sow and cover with vermiculite or fine compost/vermiculite mixture and then only mist spray the surface until germination.

[Kleftiwallah]

I have a 'device' to make small indentations in my seed trays at regular intervals and I use a 'pooter' to transfer a seed at a time from a small dish to each indentation. That way I have a very good idea how many of my seeds have germinated. I cannot say I've noticed any 'dropping off' of viability. Cheers, Tony.

[FelixLeiter]

The float test for seeds is not very instructive. It only indicates if the seeds are empty, which they are if the float, and of course they are barren if they are empty. But old, dead seeds can just as easily pass this test. Microwave a few fresh seeds (which kills them instantly) and these will pass, too.

There are so many factors involved with germinating seeds, especially "in the field", which is why germination testing is done on filter papers at carefully controlled temperatures to eliminate a few of these variables. You can do your own germination testing on damp kitchen towel, which is a good way to troubleshoot failed sowings.

I know it generally states on the packet that packaged for year such and such but that does not say how old the seed is.

The date stated on the packet does not necessarily indicate the age of the seeds contained within, only that they have passed their statutory germination test. For instance, lettuce seeds are viable for 5 years. Germination percentages during this period are high, around 80% or above. However, by year 6, this falls to nearly zero. So this means that 5 year old lettuce seed can be legally sold as viable for the year in which it is for sale because it is still vital within the statute, but if it is saved until the following year, germination rates can be disappointing. I should emphasise that most seed companies do not do this, and with new varieties you can be pretty sure that the seed in the packet will be young. I know for a fact that Suttons seeds are absolutely fresh every year. On the other hand, in my opinion, give T&M a miss. I have for the last twenty years: if their seed does actually germinate, more often that not it is mis-labelled.