Harvest Maths

[Maf]

You know how some seed packets state "Time to harvest" ie/ the number of weeks from sowing to harvest.

I know there are lots of variable but...

Anyone have any thoughts how to calculate this from sow/harvest diagrams ?

Take Spring Onion Sentry...

If first sowing is start of March and first harvest is start August thats 20 weeks.

It looks like a July sowing will crop in November say 16 weeks.

I assume the difference is to do with a slow start at the begining of the season.

Would it be safe to say that average time to harvest is 20 weeks

Your thoughs please

[Paulottie]

Temperature will affect germination time and early growth. Also daylight hours affect growth...things would be in a hurry after the solstice as they realise the season is changing...onions are quite light sensitive...but its usually a rush to but on flowers