Bean seed postmortem.

Planted some runners and dwarf french in pots, to plant out.

Germination was rapid in both cases (three or four days); for the sake of completeness weather now is hot and dry, so I've been keeping the pots damp. "Bought" compost is Westland peat free with John Innes and BIO3 (bag kept twisted closed since first use). Runners in 3' pots, french in 2" pots, all previously used.

Success rate from runners: about 87.5%. Dwarf french 50%. Failing plants all complete no-shows, i.e. no sign of germination.

Examination shows the failed beans have turned to soft paste, and have maggots, perhaps 1/4" (6.35mm) long, blunt at one end, pointy at the other end. I doubt the DF seeds have been in pots for more than 6 days total, and the ones which are OK are between just pushing up and 1 1/2" (38mm) high with proper leaves.

1. What are these likely to be?
2. Could they have come from the old pots (dry stored since last year), the compost, the seed (runners bought last year (Wilko), dwarf french this year (Wilko), or hatched from eggs since potting, or somewhere else?

"Things that make you go "Grr!""

I have some more DF to plant. Perhaps I'll sprout them in kitchen paper to see what happens.

 

I often wonder if seeds are truly ripe when the companies get them, not just beans but lots of seeds just rot, it could be old seed also, I know packets have sowing dates on, but you dont know how many years they have kept them before bagging them up, or even the place where they got them from.

 

That's very, very quick! Seed into pot, 2 days (say) until they start to rot, 24 hours between fly laying egg and hatching, then growth to 1/4" long maggot in a couple of days.

Right. I will certainly start the next beans in kitchen paper, and see what happens!

 

It's difficult. We can only trust the labelling, I guess (although that is backed up by law). Some places (e.g. Wilko) give a "germination guarantee" ("Should these seeds fail, we will be happy to replace them"). What that's worth I have never tried to find out. I'll be interested to see what the germination rate is in kitchen paper for these about 70 seeds I have remaining (dwarf french "Tendercrop", packed in Y.E. Nov 2023, sow by Dec 2026).